气相传输法制备大尺寸单晶Bi<sub>2</sub>Se<sub>3</sub>纳米片、纳米带

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李小帅, 王增梅, 朱鸣芳, 王善朋, 陶绪堂, 陆骏, 陈兴涛, 徐佳乐. 气相传输法制备大尺寸单晶Bi₂Se₃纳米片、纳米带 . 无机材料学报, 2014, 29(11): 1199-1203
LI Xiao-Shuai, WANG Zeng-Mei, ZHU Ming-Fang, WANG Shan-Peng, TAO Xu-Tang, LU Jun, CHEN Xing-Tao, XU Jia-Le. Synthesis of Jumbo-size Single Crystalline Bi₂Se₃Nanoplates and Nanoribbons by Vapor Transportation . Journal of Inorganic Materials, 2014, 29(11): 1199-1203 复制到剪切板

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气相传输法制备大尺寸单晶Bi₂Se₃纳米片、纳米带

李小帅¹, 王增梅^1,², 朱鸣芳³, 王善朋², 陶绪堂², 陆骏¹, 陈兴涛¹, 徐佳乐¹

1. 东南大学江苏省土木工程材料重点实验室, 南京211189

2. 山东大学晶体材料国家重点实验室, 济南250100

3. 东南大学江苏省先进金属材料高技术研究重点实验室, 南京211189

通讯作者: 王增梅, 教授. E-mail:zmwangster@gmail.com

作者简介: 李小帅(1990-), 男, 硕士研究生. E-mail:lixsseu@163.com

基金:国家自然科学基金(51002029); 山东大学晶体材料国家重点实验室开放课题(KF1107);

摘要

低维Bi₂Se₃纳米材料是最新研究发现的一种新型三维拓扑绝缘体材料, 在微电子器件和传感器领域具有广阔的应用前景。本研究采用气相传输法在真空石英管中合成了大尺寸单晶Bi₂Se₃纳米片、纳米带。通过XRD、EDS、Raman、SEM等手段对Bi₂Se₃纳米片、纳米带的物相结构、组成、表面形貌等进行表征。测试结果表明: 气相传输法合成的单晶Bi₂Se₃纳米片、纳米带相纯度高, 结晶性能好, 均是{001}取向; Bi₂Se₃纳米片水平尺寸大, 约为15~180 μm; Bi₂Se₃纳米带长度达860 μm, 宽度约5 μm。根据不同温度下制备的Bi₂Se₃纳米片、纳米带SEM照片及其不同方向结合能的差异, 分析了其可能的生长机制: 在较高温度下沿<001>和方向生长速度快, 生成大尺寸单晶Bi₂Se₃纳米片; 在较低温度下, 沿方向生长速度快, 生成大尺寸单晶Bi₂Se₃纳米带。这些研究结果完善了大尺寸Bi₂Se₃纳米材料的制备工艺, 有望在微电子器件领域得到商业化应用。

关键词: 气相传输法; Bi2Se3纳米片; Bi2Se3纳米带

中图分类号:TB34 文献标志码:A 文章编号:1000-324X(2014)11-1199-05

Synthesis of Jumbo-size Single Crystalline Bi₂Se₃Nanoplates and Nanoribbons by Vapor Transportation

LI Xiao-Shuai¹, WANG Zeng-Mei^1,², ZHU Ming-Fang³, WANG Shan-Peng², TAO Xu-Tang², LU Jun¹, CHEN Xing-Tao¹, XU Jia-Le¹

1. Jiangsu Key Laboratory of Construction Materials, Southeast University, Nanjing 211189, China

2. State Key Laboratory of Crystal Materials, Shandong University, Jinan, 250100, China

3. Jiangsu Key Laboratory of Advanced Metallic Materials, Southeast University, Nanjing 211189, China

Fund:Natural Science Foundation of China(51002029); Opening project for State Key Laboratory of Crystal Materials, Shandong University, China(KF1107);

Abstract

Low-dimensional Bi₂Se₃nanomaterials were discovered to be new three-dimensional (3D) topological insulators (TIs) recently, which have broad application prospect in the field of microelectronic devices and sensors. Single crystalline Bi₂Se₃nanoplates (NPs) and nanoribbons (NRs) with jumbo size were synthesized in the vacuum quartz tubevia vapor transportation. The crystal structure, composition and morphology of the as-prepared Bi₂Se₃NPs and NRs were analyzed by XRD, EDS, Raman and SEM. It is found that both of the two specimens are well-crystallized in the direction of {001} with a high purity. Bi₂Se₃NPs have a large lateral size of 15-180 μm, while Bi₂Se₃NRs have a large length of 860 μm and a width of about 5 μm. Besides, the probable growth mechanism is proposed based on the analysis of the SEM images of Bi₂Se₃NPs and NRs prepared at different temperatures and the binding energy difference along different directions. Bi₂Se₃ has a quicker growth speed along <001> and directions in relatively high temperature to form single crystalline NPs with large lateral size, while it grows faster along direction in lower temperature to get single crystalline NRs with large length. All these results not only improve the preparation process of Bi₂Se₃nanomaterials with jumbo size, but also promote the commercial use in the field of microelectronic devices.

Keyword: vapor transportation; Bi2Se3 nanoplates; Bi2Se3 nanoribbons

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A₂B₃(A=Bi, Sb; B=Se, Te)硫族化合物作为传统的热电材料, 因其室温下具有优异的热电性能, 一直是热电领域的研究热点^{[ 1, 2]}。近年来, 传统热电材料开始向低维方向发展。理论预测与实验研究均表明, 低维材料具有更高的热电优值^{[ 3, 4]}, 因为低维化使材料费米面附近载流子具有更高的态密度, 同时增加了界面处声子散射, 并且降低了晶格热导率。此外, 近几年的研究表明, Bi₂Se₃/Bi₂Te₃是一种新型的三维拓扑绝缘体材料^{[ 5, 6, 7]}, 具有表面导电、内部绝缘的特性。Bi₂Se₃因其简单的能带结构(表面有一个狄拉克锥)和较宽的体带系(0.3 eV), 使其成为研究拓扑绝缘性质的理想材料。Xiu等^{[ 8]}制备了Bi₂Se₃/ Bi₂Te₃电子器件, 系统研究了各种拓扑特性(自旋量子霍尔效应、Aharonow-Bohm效应等); Liu等^{[ 9]}在研究上述特性的同时, 探究了其超导近邻特性与电子传输特性的关系。这些研究使得其在下一代自旋器件、光学器件、光敏器件及低能耗电子器件中具有潜在的应用前景^{[ 10, 11, 12]}。然而, 对于块状Bi₂Se₃, 在费米面附近具有很高的体能带密度, 掩盖了拓扑绝缘体表面态的独特物性, 因此必须控制过量的体载流子^{[ 13]}。迄今为止, 材料工作者尝试了很多方法降低体载流子^{[ 14, 15]}。研究表明, 增大Bi₂Se₃比表面积是一种有效的方法, 制备低维Bi₂Se₃纳米片、纳米带随之成为研究的热点之一。

目前报道的制备Bi₂Se₃纳米片、纳米带的方法很多, 主要有溶剂热法^{[ 16]}、化学浴沉积^{[ 17]}(CBD)、分子束外延法^{[ 18, 19]}(MBE)、机械剥离^{[ 3]}等。气相传输法(Vapor Transportation, VT)是近年来研究较多的一种方法, Kong^{[ 20]}、Zhao^{[ 21]}、Li^{[ 22]}等先后分别用VT法合成了Bi₂Se₃/Bi₂Te₃纳米片、纳米带。然而他们制备的纳米片、纳米带尺寸较小, 且有的使用Au纳米粒子作为催化剂, 不可避免的会掺入到样品中, 引入杂质, 掩盖低维Bi₂Se₃的拓扑绝缘特性, 这些都会限制低维Bi₂Se₃材料的实际应用。本研究采用VT法制备了水平尺寸达几百微米甚至毫米级的超大尺寸Bi₂Se₃纳米片、纳米带, 并对其物相与形貌进行了分析表征, 重点探究了其可能的生长机制, 完善了大尺寸Bi₂Se₃纳米片、纳米带的制备工艺, 有望加快低维Bi₂Se₃材料的商业化生产应用步伐。

1 实验方法

1.1 样品制备

Bi₂Se₃纳米片、纳米带的制备分两步进行: 1) 制备Bi₂Se₃块体, 提供原料; 2) 利用VT法生长Bi₂Se₃纳米片、纳米带。具体制备过程如下:

Bi₂Se₃块体采用高温真空熔炼制备, 过程如下: 1) 按照化学计量比称取一定量的铋粉和硒粉, 装入内径15 mm的石英管中, 用分子泵将石英管抽真空至3×10^-3Pa, 并密封; 2) 将石英管倾斜放入真空管式炉中, 升温至750 ℃, 并保温70 h, 随炉冷却至室温, 打开石英管, 得到Bi₂Se₃块体。

Bi₂Se₃纳米片采用VT法制备, 过程如下: 1) 将上述制备好的Bi₂Se₃块体研磨成粉末, 称取0.1 mmol Bi₂Se₃粉末, 装入一端封闭内径8 mm的石英管一端, 另一端垂直放入Si衬底, 抽真空至3×10^-3 Pa, 密封石英管; 2) 将石英管水平放入真空管式炉中, 原料端温度设置为700 ℃, 衬底端温度设为350℃~ 450℃, 保温24 h, 随炉冷却。实验装置示意图如图1所示。

1.2 样品表征

样品的物相结构采用X射线衍射仪(XRD, Bruker D8-Discover, Cu Kα辐射)进行表征; 利用能谱仪(EDS, genesis) 分析样品的元素含量; 采用共聚焦拉曼光谱仪(Raman, LabRAM HR UV-Visible)进一步对物相进行鉴定, 分析样品的结构。采用场发射扫描电镜(SEM, Sirion 200, 20 kV)分析样品的表面形貌特征。

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	图1 气相传输法制备Bi₂Se₃纳米片、纳米带实验装置示意图Fig. 1 Schematic of experimental setup for the synthesis of Bi₂Se₃nanoplates and nanoribbons with vapor transportationⅠ: 700℃; Ⅱ: 350℃-450℃

2 结果与讨论

2.1 物相与结构分析

图2为高温真空熔炼制备的Bi₂Se₃块体, 呈银白色金属光泽。该块体被敲碎后, 会得到很多Bi₂Se₃薄片。仔细观察发现, 这些薄片是由厚度更小的很多薄片组成, 显示出Bi₂Se₃的层状结构特征。层间结构致密, 表明合成了质量较好的Bi₂Se₃块体。

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	图2 高温真空熔炼制备的Bi₂Se₃块体Fig. 2 Bulk Bi₂Se₃ synthesized by vacuum melting at high temperature

Bi₂Se₃块体、Bi₂Se₃纳米片和Bi₂Se₃纳米带的XRD图谱如图3所示。从图中可以看出, Bi₂Se₃块体、Bi₂Se₃纳米片和Bi₂Se₃纳米带的所有衍射峰都与其标准衍射图谱(JCPDS 33-214)相吻合, 且衍射峰强度较高, 没有杂峰出现, 表明合成的是纯Bi₂Se₃相, 且结晶性很好。Bi₂Se₃块体的三个主峰是 (006)、(0, 0, 15)和(0, 0, 21), 都属于{001}晶面族, 此外, 在{101}面上有较低的两个衍射峰出现, 分别为(104)和(1, 0, 16), 说明合成的Bi₂Se₃块体主要是(001)取向, 还有部分为(101)取向。而Bi₂Se₃纳米片和纳米带仅有三个取向为(006)、(0, 0, 15)和(0, 0, 21) (该峰被基底SiO₂强烈的衍射峰掩盖, 没有单独显示) 的主峰, 均属于{001}晶面族, 在{101}晶面有极微弱的衍射峰出现, 可以忽略不计, 表明VT法制备的均为{001}取向的大尺寸单晶Bi₂Se₃纳米片和纳米带。

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	图3 Bi₂Se₃块体、纳米片和纳米带的XRD图谱Fig. 3 XRD patterns of bulk Bi₂Se₃, Bi₂Se₃nanoplates and Bi₂Se₃nanoribbons

Bi₂Se₃纳米片和Bi₂Se₃纳米带的能谱图(EDS)如图4(a, b)所示, 强烈的Si峰来自衬底。Bi₂Se₃纳米片和Bi₂Se₃纳米带中元素Bi和Se的化学计量比分别为40.11: 59.89和39.11: 60.89, 均近似于2: 3, 可以看成是Bi₂Se₃的标准化学计量比, 表明合成的是纯的Bi₂Se₃相。

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	图4 Bi₂Se₃纳米片(a)和Bi₂Se₃纳米带(b)的EDS图谱Fig. 4 EDS spectra of Bi₂Se₃nanoplates (a) and Bi₂Se₃nanoribbons (b)

采用拉曼光谱法分析了Bi₂Se₃材料的组成和结构^{[ 23]}, 图5为Bi₂Se₃块体、Bi₂Se₃纳米片和Bi₂Se₃纳米带的拉曼光谱图, 激发波长为514 nm, 光斑作用直径约1 μm。受限于仪器波数测量范围, 本实验只得到Bi₂Se₃的两个高波数特征峰和,表示层间面内振动模式(in-plane vibrational mode), 原子在面内沿水平方向振动;表示面外振动模式(out-plane vibrational mode), 原子沿垂直于面方向振动^{[ 24]}, 峰值高低反映了其振动强弱。图中两特征峰分别对应131 cm^-1和174 cm^-1, 与其标准拉曼特征峰值一致, 表明合成的是纯Bi₂Se₃相。Bi₂Se₃块体的特征峰很弱, 明显低于Bi₂Se₃纳米片和Bi₂Se₃纳米带, 因为Bi₂Se₃块体厚度大, 原子的振动受到极大限制, 极化率降低, 因此振动较弱; Bi₂Se₃纳米带的峰值最强, 主要是纳米带较窄, 且厚度相对较小, 原子振动受到的限制作用最小, 极化率较高, 因此具有较大的振动强度^{[ 25]}; 两个Bi₂Se₃纳米片的峰值强度介于块体与纳米带之间, 且二者之间有少量差异, 这与两纳米片的厚度及微区结构差异有关。仔细观察还可发现, Bi₂Se₃纳米带的特征峰发生了红移(red shift), 约3~4 cm^-1, 可能是缺陷引起的声子限域效应, 使得能隙减小, 产生红移^{[ 26]}。

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	图5 Bi₂Se₃块体、纳米片和纳米带的Raman光谱Fig. 5 Raman spectra of bulk Bi₂Se₃, Bi₂Se₃nanoplates and Bi₂Se₃nanoribbons

2.2 样品形貌及生长机理分析

Bi₂Se₃纳米片和纳米带的制备可以通过调节衬底端温度来控制。当衬底端温度为~450℃时, 得到Bi₂Se₃纳米片; 当衬底端温度为~350℃时, 得到Bi₂Se₃纳米带。

图6(a~d)为~450℃时得到的Bi₂Se₃纳米片的扫描电镜照片。图6(a, b)中Bi₂Se₃纳米片呈规则的平行四边形状, 两个夹角分别为60°和120°, 水平尺寸约15~180 μm, 可以看成是Bi₂Se₃本征六边形结构沿(0001)面结合。而纳米片表面光滑, 无明显杂质。图6(c, d)中Bi₂Se₃纳米片水平尺寸约20~30 μm, 从图6(c)中可以明显看出, 该纳米片的右下角长出一个尺寸约3 μm的六边形Bi₂Se₃纳米片, 3个面形成台阶(如图中箭头所示)。图6(d)中Bi₂Se₃纳米片为规则的六边形状, 层状结构清晰可见(如图中箭头所示), 层与层之间以台阶方式堆叠, 属于典型的台阶生长机制^{[ 10, 27]}: 原子以底部晶格为模板, 按本征结构形核长大, 逐渐产生台阶, 是一个螺旋长大的过程。

图6(e~h)为~350℃时制备的Bi₂Se₃纳米带的扫描电镜照片。图6(e)中Bi₂Se₃纳米带长度达860 μm, 宽度约5 μm, 高倍图像显示纳米带表面平整, 粗糙度很低, 足以用来制备Bi₂Se₃微电子器件, 图6(g)中Bi₂Se₃纳米带尺寸相对较小, 长度约100 μm, 宽度约1.8 μm。该纳米带上部覆盖一层尺寸更大更薄的Bi₂Se₃纳米带, 可能是依附在该纳米带上生长所得。此外, 在该纳米带旁边, 长出一个长度约10 μm, 宽度约1.6 μm的超薄Bi₂Se₃纳米带, 可以清晰看到衬底。在该纳米带下面, 同样有一个尺寸稍小的Bi₂Se₃纳米带, 可能是依附在该纳米带上生长。

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	图6 不同放大倍数下Bi₂Se₃纳米片(a~d)、Bi₂Se₃纳米带(e~h)的SEM照片Fig. 6 SEM images of Bi₂Se₃nanoplates (a-d) and Bi₂Se₃nanoribbons (e-h) at different magnifications

基于不同温度下制备的Bi₂Se₃纳米片和纳米带的SEM照片, 本实验分析了Bi₂Se₃可能的生长机制。Bi₂Se₃是层状菱形斜六面体晶体结构, 在<001>方向由组成为Se-Bi-Se-Bi-Se的一个个单元层组成^{[ 28, 29]}, 层内原子由很强的共价键连接, 而单元层之间靠很弱的范德华力连接。由于各向异性的结构特征, Bi₂Se₃不同面之间结合能不同, 因此沿不同方向的生长速率不同^{[ 30]}。Bi₂Se₃沿<001>和方向的结合能高于方向, 在较高温度(~450℃)时, 气体分子有很高的能量, 足以克服<001>方向和方向的结合能, 因此在该方向有较高的生长速率, 进行外延和堆叠生长, 生成图6(a~d) 所示Bi₂Se₃纳米片; 当温度较低时(~350℃), 气体分子能量不足以克服<001>方向和方向的结合能,方向的生长起主导作用, 生成图6(e~h) 中Bi₂Se₃纳米带。可以推测, 如果进一步降低形核温度(能量仍足以克服结合能), 很可能会生成 Bi₂Se₃纳米线, 这一假设也在Yan等^{[ 30]}的研究中得到验证。

3 结论

利用VT法, 成功在真空石英管中合成了超大尺寸单晶Bi₂Se₃纳米片、纳米带。Bi₂Se₃纳米片水平尺寸大, 约为15~180 μm, 相纯度高, 结晶性好; Bi₂Se₃纳米带长度达860 μm, 宽度约5 μm, 结晶性能好, 足以用来制备Bi₂Se₃微电子器件。根据Bi₂Se₃纳米片、纳米带不同方向结合能不同, 分析了其在不同温度下的生长机制; 在较高温度下倾向于沿<001>和方向按外延和螺旋生长机制生成大尺寸Bi₂Se₃纳米片; 温度较低时, 倾向于沿方向生成超长Bi₂Se₃纳米带。这些研究结果丰富了大尺寸Bi₂Se₃纳米材料的制备方法, 有望推动其在微电子器件领域的商业化应用。

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[4]	QI XIAO-LIANG, ZHANG SHOU-CHENG. Topological insulators and superconductors. Rev. Mod. Phys. , 2011, 83(4): 1057-1110. [本文引用:1] [JCR: 44.982]
[5]	CAO HE-LIN, XU SU-YANG, MIOTKOWSKI I, et al. Structural and electronic properties of highly doped topological insulator Bi₂Se₃ crystals. Phys. Status Solidi RRL, 2013, 7: 133-135. [本文引用:1]
[6]	ZHANG QIAN-FAN, ZHANG ZHI-YONG, ZHU ZHI-YONG, et al. Exotic topological insulator states and topological phase transitions in Sb₂Se₃-Bi₂Se₃ heterostructures. ACS Nano, 2012, 6(3): 2345-2352. [本文引用:1] [JCR: 12.062]
[7]	WANG JING, ZHU BANG-FEN. Elastic scattering of surface states on three-dimensional topological insulators. Chin. Phys. B, 2013, 22(6): 067301-067309. [本文引用:1] [JCR: 1.148] [CJCR: 1.2429]
[8]	XIU FA-XIAN, ZHAO TONG-TONG. Topological insulator nanostructures and devices. Chin. Phys. B, 2013, 22(9): 096104-096117. [本文引用:1] [JCR: 1.148] [CJCR: 1.2429]
[9]	LIU YI, MA ZHENG, ZHAO YAN-FEI, et al. Transport properties of topological insulators films and nanowires. Chin. Phys. B, 2013, 22(6): 067302-067315. [本文引用:1] [JCR: 1.148] [CJCR: 1.2429]
[10]	MIN Y, MOON G D, KIM B S, et al. Quick, controlled synthesis of ultrathin Bi₂Se₃ nanodiscs and nanosheets. J. Am. Chem. Soc. , 2012, 134: 2872-2875. [本文引用:2] [JCR: 10.677]
[11]	CHEN Y L, CHU J H, ANALYTIS J G, et al. Massive dirac fermion on the surface of a magnetically doped topological insulator. Science, 2010, 329: 659-662. [本文引用:1]
[12]	KIRSHENBAUM K, SYERS P S, HOPE A P, et al. Pressure- induced unconventional superconducting phase in the topological insulator Bi₂Se₃. Phys. Rev. Lett. , 2013, 111(8): 087001-087005. [本文引用:1] [JCR: 7.943]
[13]	KONG DE-SHENG, KOSKI K J, CHA J, et al. Ambipolar field effect in Sb-doped Bi₂Se₃ nanoplates by solvothermal synthesis. Nano Lett. , 2013, 13: 632-636. [本文引用:1] [JCR: 13.025]
[14]	PENG HAI-LIN, LAI KE-JI, KONG DE-SHENG, et al. Aharonov- Bohm interference in topological insulator nanoribbons. Nat. Mater, 2010, 9: 225-229. [本文引用:1] [JCR: 35.749]
[15]	ZHANG YI, HE KE, CHANG CUI-ZU, et al. Crossover of the three-dimensional topological insulator Bi₂Se₃ to the two- dime-nsional limit. Nat. Phys. , 2010, 6: 584-588. [本文引用:1] [JCR: 19.352]
[16]	ZHANG GEN-QIANG, WANG WEI, LU XIAO-LI, et al. Solvothermal synthesis of Ⅴ-Ⅵ binary and ternary hexagonal platelets: the oriented attachment mechanism. Cryst. Growth Des. , 2009, 9(1): 145-150. [本文引用:1] [JCR: 4.689]
[17]	SUN ZHENG-LIANG, CONG SHENG, FU LIU, et al. A general strategy to bismuth chalcogenide films by chemical vapor transport. J. Mater. Chem. , 2011, 21: 2351-2355. [本文引用:1] [JCR: 5.968]
[18]	CHEN XI, MA XU-CUN, HE KE, et al. Molecular beam epitaxial growth of topological insulators. Adv. Mater. , 2011, 23: 1162-1165. [本文引用:1] [JCR: 14.829]
[19]	XIE MAO-HAI, GUO XIN, XU ZHONG-JIE, et al. Molecular-beam epitaxy of topological insulator Bi₂Se₃ (111) and (221) thin films. Chin. Phys. B, 2013, 22(6): 068101-068108. [本文引用:1] [JCR: 1.148] [CJCR: 1.2429]
[20]	KONG DE-SHENG, DANG WEN-HUI, J. CHA J, et al. Few-layer nanoplates of Bi₂Se₃ and Bi₂Te₃ with highly tunable chemical potential. Nano Lett. , 2010, 10: 2245-2250. [本文引用:1] [JCR: 13.025]
[21]	ZHAO YI-MIN, HUGHES R W, SU ZI-XUE, et al. One-step synthesis of bismuth telluride nanosheets of a few quintuple layers in thickness. Angew. Chem. Int. Ed. , 2011, 50: 10397-10401. [本文引用:1]
[22]	LI HUI, CAO JIE, ZHENG WEN-SHAN, et al. Controlled synthesis of topological insulator nanoplate arrays on mica. J. Am. Chem. Soc. , 2012, 134: 6132-6135. [本文引用:1] [JCR: 10.677]
[23]	KIM T H, BAECK J H, CHOI H, et al. Phase transformation of alternately layered Bi/Se structure to well-ordered single crystalline Bi₂Se₃ structures by a self-organized ordering process. J. Phys. Chem. C, 2012, 116: 3737-3746. [本文引用:1] [JCR: 4.814]
[24]	DANG WEN-HUI, PENG HAI-LIN, LI HUI, et al. Epitaxial heterostructures of ultrathin topological insulator nanoplate and graphene. Nano Lett. , 2010, 10: 2870-2876. [本文引用:1] [JCR: 13.025]
[25]	ZHANG JUN, PENG ZE-PING, SONI A, et al. Raman spectroscopy of few-quintuple layer topological insulator Bi₂Se₃ nanoplatelets. Nano Lett. , 2011, 11: 2407-2414. [本文引用:1] [JCR: 13.025]
[26]	SONI A, ZHAO YAN-YUAN, YU LI-GEN, et al. Enhanced thermoelectric properties of solution grown Bi₂Te_3-xSe_x nanoplatelet composites. Nano Lett. , 2012, 12: 1203-1209. [本文引用:1] [JCR: 13.025]
[27]	LIU H W, YUAN H T, FUKUI N, et al. Growth of topological insulator Bi₂Te₃ ultrathin films on Si (111) investigated by low-energy electron microscopy. Crystal Growth & Design, 2010, 10(10): 4491-4493 [本文引用:1] [JCR: 4.689]
[28]	CHA J J, KOSKI K J, CUI Y. Topological insulator nanostructures. Phys. Status Solidi RRL, 2013, 7: 15-25. [本文引用:1]
[29]	KOSKI K J, WESSELLS C D, REED B W, et al. Chemical intercalation of zerovalent metals into 2D layered Bi₂Se₃ nanoribbons. J. Am. Chem. Soc, 2012, 134: 13773-13779. [本文引用:1] [JCR: 10.677]
[30]	YAN YUAN, LIAO ZHI-MIN, ZHOU YANG-BO, et al. Synthesis and quantum transport properties of Bi₂Se₃ topological insulator nanostructures. Nature, 2013, 3: 1264-1268. [本文引用:2] [JCR: 38.597]

1993

0.0

Phys. Rev. B. 1993, 47(19):chrome=1" http-equiv="X-UA-Compatible" /><title>Phys. Rev. B 47, 12727-null

... B=Se, Te)硫族化合物作为传统的热电材料, 因其室温下具有优异的热电性能, 一直是热电领域的研究热点^[1,2] ...

2005

0.71

0.0

... B=Se, Te)硫族化合物作为传统的热电材料, 因其室温下具有优异的热电性能, 一直是热电领域的研究热点^[1,2] ...

2010

13.025

0.0

Nano Lett.. 2010, 10(4):1209–1218-null

Exfoliation and Characterization of Bismuth Telluride Atomic Quintuples and Quasi-Two-Dimensional Crystals

Desalegne Teweldebrhan , Vivek Goyal and Alexander A. Balandin *

Nano-Device Laboratory, Department of Electrical Engineering and Materials Science and Engineering Program, Bourns College of Engineering, University of California—Riverside, Riverside, California 92521 * Corresponding author, balandin@ee.ucr.edu or http://ndl.ee.ucr.edu .

Bismuth telluride (Bi 2 Te 3 ) and its alloys are the best bulk thermoelectric materials known today. In addition, stacked quasi-two-dimensional (2D) layers of Bi 2 Te 3 were recently identified as promising topological insulators. In this Letter we describe a method for “graphene-inspired” exfoliation of crystalline bismuth telluride films with a thickness of a few atoms. The atomically thin films were suspended across trenches in Si/SiO 2 substrates, and subjected to detail material characterization, which included atomic force microscopy and micro-Raman spectroscopy. The presence of the van der Waals gaps allowed us to disassemble Bi 2 Te 3 crystal into its quintuple building blocks—five monatomic sheets—consisting of Te (1) −Bi−Te (2) −Bi−Te (1) . By altering the thickness and sequence of atomic planes, we were able to create “designer” nonstoichiometric quasi-2D crystalline films, change their composition and doping, the type of charge carriers as well as other properties. The exfoliated quintuples and ultrathin films have low thermal conductivity, high electrical conductivity, and enhanced thermoelectric properties. The obtained results pave the way for producing stacks of crystalline bismuth telluride quantum wells with the strong spatial confinement of charge carriers and acoustic phonons, beneficial for thermoelectric devices. The developed technology for producing free-standing quasi-2D layers of Te (1) −Bi−Te (2) −Bi−Te (1) creates an impetus for investigation of the topological insulators and their possible practical applications.

... 理论预测与实验研究均表明, 低维材料具有更高的热电优值^[3,4], 因为低维化使材料费米面附近载流子具有更高的态密度, 同时增加了界面处声子散射, 并且降低了晶格热导率 ...

... 目前报道的制备Bi₂Se₃纳米片、纳米带的方法很多, 主要有溶剂热法^[16]、化学浴沉积^[17](CBD)、分子束外延法^[18,19](MBE)、机械剥离^[3]等 ...

2011

44.982

0.0

Rev. Mod. Phys.. 2011, 83(4):chrome=1" http-equiv="X-UA-Compatible" /><title>Rev. Mod. Phys. 83, 1057-null

2013

0.0

physica status solidi (RRL) - Rapid Research Letters. 2013, 7(1‐2):133-135

Structural and electronic properties of highly doped topological insulator Bi₂Se₃ crystals

Helin Cao 1,2,* ,Suyang Xu 3,4 ,Ireneusz Miotkowski 1 ,Jifa Tian 1,2 ,Deepak Pandey 1,2 ,M. Zahid Hasan 3,4 andYong P. Chen 1,2,5,*

1 Department of Physics, Purdue University, 525 Northwestern Ave., West Lafayette, IN 47907, USA 2 Birck Nanotechnology Center, Purdue University, 1205 W. State St., West Lafayette, IN 47907, USA 3 Joseph Henry Laboratories, Department of Physics, Princeton University, Jadwin Hall, Princeton, NJ 08544, USA 4 Princeton Institute for Science and Technology of Materials, Princeton University, 70 Prospect Ave., Princeton, NJ 08544, USA 5 School of Electrical and Computer Engineering, Purdue University, 465 Northwestern Ave., West Lafayette, IN 47907 USA * Phone: +01 765 496 3059, Fax: +01 765 494 0706

... 此外, 近几年的研究表明, Bi₂Se₃/Bi₂Te₃是一种新型的三维拓扑绝缘体材料^[5,6,7], 具有表面导电、内部绝缘的特性 ...

2012

12.062

0.0

ACS Nano. 2012, 6(3):2345–2352-null

Exotic Topological Insulator States and Topological Phase Transitions in Sb₂Se₃–Bi₂Se₃ Heterostructures

Qianfan Zhang † , Zhiyong Zhang ‡ , Zhiyong Zhu § , Udo Schwingenschlögl § , and Yi Cui † ⊥ *

† Department of Material Sciences and Engineering and ‡ Stanford Nanofabrication Facility, Stanford University , Stanford, California 94305, United States § PSE Division, KAUST , Thuwal 23955-6900, Saudi Arabia ⊥ Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory , 2575 Sand Hill Road, Menlo Park, California 94025, United States *Address correspondence to yicui@stanford.edu .

Topological insulator is a new state of matter attracting tremendous interest due to its gapless linear dispersion and spin momentum locking topological states located near the surface. Heterostructures, which have traditionally been powerful in controlling the electronic properties of semiconductor devices, are interesting for topological insulators. Here, we studied the spatial distribution of the topological state in Sb 2 Se 3 –Bi 2 Se 3 heterostructures by first-principle simulation and discovered that an exotic topological state exists. Surprisingly, the state migrates from the nontrivial Bi 2 Se 3 into the trivial Sb 2 Se 3 region and spreads across the entire Sb 2 Se 3 slab, extending beyond the concept of “surface” state while preserving all of the topological surface state characteristics. This unusual topological state arises from the coupling between different materials and the modification of electronic structure near Fermi energy. Our study demonstrates that heterostructures can open up opportunities for controlling the real-space distribution of the topological state and inducing quantum phase transitions between topologically trivial and nontrivial states.

... 此外, 近几年的研究表明, Bi₂Se₃/Bi₂Te₃是一种新型的三维拓扑绝缘体材料^[5,6,7], 具有表面导电、内部绝缘的特性 ...

2013

1.148

1.2429

Chin. Phys. B. 2013, 22(6):067301-067309 DOI:10.1088/1674-1056/22/6/067301

Elastic scattering of surface states on three-dimensional topological insulators

Key Laboratory for Photonic and Electronic Band-Gap Materials, National Ministry of Education, and School of Physics and Electronic Engineering,Harbin Normal University, Harbin 150025, China

We present a metallic/dielectric multi-wedge model to investigate the coupled edge plasmon modes (CEPMs), where all wedges have a common edge and the wave propagates along the edge direction. A general theoretical method valid to many practical structures is presented. The analytical dispersion relations of CEPMs in these structures are obtained and the CEPM properties are discussed with numerical results and the dispersion relations. For all structures mentioned in this paper, we find that the structures containing an even number of metallic wedges own four CEPMs and those with an odd-number of metallic wedges have two CEPMs. Further the periodic structures containing any odd number of periods and any even number of periods possess their common CEPMs, respectively.

... 此外, 近几年的研究表明, Bi₂Se₃/Bi₂Te₃是一种新型的三维拓扑绝缘体材料^[5,6,7], 具有表面导电、内部绝缘的特性 ...

2013

1.148

1.2429

Chin. Phys. B. 2013, 22(9):096104-096117 DOI:10.1088/1674-1056/22/09/096104

Topological insulator nanostructures and devices

State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China

Topological insulators’ properties and their potential device applications are reviewed. We also explain why topological insulator (TI) nanostructures are an important avenue for research and discuss some methods by which TI nanostructures are produced and characterized. The rapid development of high-quality TI nanostructures provides an ideal platform to exploit salient physical phenomena that have been theoretically predicted but not yet experimentally realized.

... Xiu等^[8]制备了Bi₂Se₃/ Bi₂Te₃电子器件, 系统研究了各种拓扑特性(自旋量子霍尔效应、Aharonow-Bohm效应等) ...

2013

1.148

1.2429

Chin. Phys. B. 2013, 22(6):067302-067315 DOI:10.1088/1674-1056/22/6/067302

Transport properties of topological insulators films and nanowires

State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, China

A novel low specific on-resistance ( R on,sp ) silicon-on-insulator (SOI) p-channel lateral double-diffused metal-oxide semiconductor (pLDMOS) compatible with high voltage (HV) n-channel LDMOS (nLDMOS) is proposed. The pLDMOS is built in the N-type SOI layer with a buried P-type layer acting as a current conduction path in the on-state (BP SOI pLDMOS). Its superior compatibility with the HV nLDMOS and low voltage (LV) complementary metal-oxide semiconductor (CMOS) circuitry which are formed on the N-SOI layer can be obtained. In the off-state the P-buried layer built in the N-SOI layer causes multiple depletion and electric field reshaping, leading to an enhanced (reduced surface field) (RESURF) effect. The proposed BP SOI pLDMOS achieves not only an improved breakdown voltage ( BV ) but also a significantly reduced R on,sp . The BV of the BP SOI pLDMOS increases to 319 V from 215 V of the conventional SOI pLDMOS at the same half cell pitch of 25 μ, and R on,sp decreases from 157 mΩ·cm 2 to 55 mΩ·cm 2 . Compared with the PW SOI pLDMOS, the BP SOI pLDMOS also reduces the R on,sp by 34% with almost the same BV .

... Liu等^[9]在研究上述特性的同时, 探究了其超导近邻特性与电子传输特性的关系 ...

2012

10.677

0.0

J. Am. Chem. Soc.. 2012, 134(6):2872–2875-null

Quick, Controlled Synthesis of Ultrathin Bi₂Se₃ Nanodiscs and Nanosheets

Yuho Min † , Geon Dae Moon † , Bong Soo Kim † , Byungkwon Lim ‡ , Jin-Sang Kim ∥ , Chong Yun Kang ∥ , and Unyong Jeong * †

† Department of Materials Science and Engineering, Yonsei University , 134 Shinchon-dong, Seoul, Korea ‡ School of Advanced Materials Science and Engineering, Sungkyunkwan University , Suwon 440-746, Korea ∥ Electronic Materials Research Center, KIST , Seoul, Korea ujeong@yonsei.ac.kr

Ultrathin (4–6 nm) single-crystal Bi 2 Se 3 nanodiscs and nanosheets were synthesized through a simple and quick solution process. The growth mechanism was investigated in detail. Crystal seeds grew via 2D self-attachment of small nanoparticles followed by epitaxial recrystallization into single crystals. The lateral dimension of the nanodiscs increased and their shape changed from circles to hexagons as the reaction temperature increased. Positively charged polymer surfactants greatly enlarged the lateral dimension to produce nanosheets with uniform thickness.

... 这些研究使得其在下一代自旋器件、光学器件、光敏器件及低能耗电子器件中具有潜在的应用前景^[10,11,12] ...

... 图6(d)中Bi₂Se₃纳米片为规则的六边形状, 层状结构清晰可见(如图中箭头所示), 层与层之间以台阶方式堆叠, 属于典型的台阶生长机制^{[10, 27]}: 原子以底部晶格为模板, 按本征结构形核长大, 逐渐产生台阶, 是一个螺旋长大的过程 ...

2010

0.0

Science. 2010, 329(5992):659-662

Massive Dirac Fermion on the Surface of a Magnetically Doped Topological Insulator

Y. L. Chen 1 , 2 , 3 , J.-H. Chu 1 , 2 , J. G. Analytis 1 , 2 , Z. K. Liu 1 , 2 , K. Igarashi 4 , H.-H. Kuo 1 , 2 , X. L. Qi 1 , 2 , S. K. Mo 3 , R. G. Moore 1 , D. H. Lu 1 , M. Hashimoto 2 , 3 , T. Sasagawa 4 , S. C. Zhang 1 , 2 , I. R. Fisher 1 , 2 , Z. Hussain 3 , Z. X. Shen 1 , 2 , *

1 Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park,CA 94025, USA. 2 Geballe Laboratory for Advanced Materials, Departments of Physics and Applied Physics, Stanford University, Stanford, CA 94305,USA. 3 Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA. 4 Materials and Structures Laboratory, Tokyo Institute of Technology, Kanagawa 226-8503, Japan. ↵ *To whom correspondence should be addressed. E-mail: zxshen@stanford.edu

... 这些研究使得其在下一代自旋器件、光学器件、光敏器件及低能耗电子器件中具有潜在的应用前景^[10,11,12] ...

2013

7.943

0.0

Phys. Rev. Lett.. 2013, 111(8):chrome=1" http-equiv="X-UA-Compatible" /><title>Phys. Rev. Lett. 111, 087001-null

... 这些研究使得其在下一代自旋器件、光学器件、光敏器件及低能耗电子器件中具有潜在的应用前景^[10,11,12] ...

2013

13.025

0.0

Nano Lett.. 2013, 13(2):632–636-null

Ambipolar Field Effect in Sb-Doped Bi₂Se₃ Nanoplates by Solvothermal Synthesis

Desheng Kong † , Kristie J. Koski † , Judy J. Cha † , Seung Sae Hong ‡ , and Yi Cui * † §

† Department of Materials Science & Engineering, Stanford University , Stanford, California 94305, United States ‡ Department of Applied Physics, Stanford University , Stanford, California 94305, United States § Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory , 2575 Sand Hill Road, Menlo Park, California 94025, United States *E-mail yicui@stanford.edu .

A topological insulator is a new phase of quantum matter with a bulk band gap and spin-polarized surface states, which might find use in applications ranging from electronics to energy conversion. Despite much exciting progress in the field, high-yield solution synthesis has not been widely used for the study of topological insulator behavior. Here, we demonstrate that solvothermally synthesized Bi 2 Se 3 nanoplates are attractive for topological insulator studies. The carrier concentration of these Bi 2 Se 3 nanoplates is controlled by compensational Sb doping during the synthesis. In low-carrier-density, Sb-doped Bi 2 Se 3 nanoplates, we observe pronounced ambipolar field effect that demonstrates the flexible manipulation of carrier type and concentration for these nanostructures. Solvothermal synthesis offers an affordable, facile approach to produce high-quality nanomaterials to explore the properties of topological insulators.

... 然而, 对于块状Bi₂Se₃, 在费米面附近具有很高的体能带密度, 掩盖了拓扑绝缘体表面态的独特物性, 因此必须控制过量的体载流子^[13] ...

2010

35.749

0.0

... 迄今为止, 材料工作者尝试了很多方法降低体载流子^[14,15] ...

2010

19.352

0.0

Nature Physics. 2010, 6(8):584-588

Crossover of the three-dimensional topological insulator Bi2Se3 to the two-dimensional limit

A topological insulator 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 is a new state of quantum matter that is characterized by a finite energy gap in the bulk and gapless modes flowing along the boundaries that are robust against disorder scattering. The topological protection of the surface state could be useful for both low-power electronics 10 and error-tolerant quantum computing 11 , 12 . For a thin slab of three-dimensional topological insulator, the boundary modes from the opposite surfaces may be coupled by quantum tunnelling, so that a small, thickness-dependent gap is opened up 13 , 14 , 15 . Here we report such results from angle-resolved photoemission spectroscopy on Bi 2 Se 3 films of various thicknesses grown by molecular beam epitaxy. The energy gap opening is clearly seen when the thickness is below six quintuple layers. The gapped surface states also exhibit sizeable Rashba-type spin–orbit splitting because of the substrate-induced potential difference between the two surfaces. The tunable gap and the spin–orbit coupling make these topological thin films ideal for electronic and spintronic device applications.

... 迄今为止, 材料工作者尝试了很多方法降低体载流子^[14,15] ...

2009

4.689

0.0

Growth Des.. 2009, 9(1):145–150-null

Solvothermal Synthesis of V−VI Binary and Ternary Hexagonal Platelets: The Oriented Attachment Mechanism

Genqiang Zhang , Wei Wang , Xiaoli Lu and Xiaoguang Li *

Hefei National Laboratory for Physical Sciences at Microscale, Department of Physics, University of Science and Technology of China, Hefei 230026, P. R. China, and the International Center for Materials Physics Academia Sinica, Shenyang 110015, P. R. China * To whom correspondence should be addressed. Tel./Fax: 86-551-3603408 . E-mail: lixg@ustc.edu.cn .

General synthesis of both binary and ternary V−VI based thermoelectric alloy hexagonal platelets was carried out for the first time in a unified system using a modified solvothermal method, which adopted convenient oxides as source materials and friendly ethylene glycol as both solvent and reducing agent. The structure and composition analysis reveal that the samples are pure phase with corresponding atomic ratios. Electron microscopy results indicate that the as-prepared products are uniform and highly crystallized. The formation process was studied in detail by observing time-dependent products, and it was found that the oriented attachment mechanism could be responsible for the growth of these hexagonal platelets, which exhibits intrinsic difference compared with the inferred seed-mediated growth mechanism in previous reports. The influence of pH value and polyvinyl pyrrolidone on the morphology of the products was investigated as well. This work may open up a new rationale on designing the solution synthesis of nanostructures for materials possessing similar intrinsic crystal symmetry.

... 目前报道的制备Bi₂Se₃纳米片、纳米带的方法很多, 主要有溶剂热法^[16]、化学浴沉积^[17](CBD)、分子束外延法^[18,19](MBE)、机械剥离^[3]等 ...

2011

5.968

0.0

... 目前报道的制备Bi₂Se₃纳米片、纳米带的方法很多, 主要有溶剂热法^[16]、化学浴沉积^[17](CBD)、分子束外延法^[18,19](MBE)、机械剥离^[3]等 ...

2011

14.829

0.0

Advanced Materials. 2011, 23(9):1162-1165

Molecular Beam Epitaxial Growth of Topological Insulators

Xi Chen 1,* ,Xu-Cun Ma 2 ,Ke He 2 ,Jin-Feng Jia 1 andQi-Kun Xue 1,2,*

1 Department of Physics, Tsinghua University, Beijing 100084, China 2 Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China * Department of Physics, Tsinghua University, Beijing 100084, China.

> With the molecular beam epitaxy technique, layer-by-layer growth of atomically flat topological insulator Bi 2 Te 3 and Bi 2 Se 3 thin films has been realized on Si(111) and graphene substrates, respectively. The growth criteria by which intrinsic topological insulators can readily be obtained is established. By using in situ angle-resolved photoemission spectroscopy and scanning tunneling microscopy measurements, the band structure and surface morphology of Bi 2 Te 3 and Bi 2 Se 3 thin films of different thickness can be studied. Molecular beam epitaxy technique was shown to not only provide an excellent method to prepare high quality topological insulators but show possibilities of engineering their electronic and spin structures as well, which is of significant importance for potential applications of topological insulators based on well-developed Si technology.

... 目前报道的制备Bi₂Se₃纳米片、纳米带的方法很多, 主要有溶剂热法^[16]、化学浴沉积^[17](CBD)、分子束外延法^[18,19](MBE)、机械剥离^[3]等 ...

2013

1.148

1.2429

Chin. Phys. B. 2013, 22(6):068101-068108 DOI:10.1088/1674-1056/22/6/068101

Molecular-beam epitaxy of topological insulator Bi₂Se₃ (111) and (221) thin films

Physics Department, The University of Hong Kong, Pokfulam Road, Hong Kong, China

This paper presents an overview of growth of Bi 2 Se 3 , a prototypical three-dimensional topological insulator, by molecular-beam epitaxy on various substrates. Comparison is made between growth of Bi 2 Se 3 (111) on van der Waals (vdW) and non-vdW substrates, with attention paid to twin suppression and strain. Growth along the [221] direction of Bi 2 Se 3 on InP (001) and GaAs (001) substrates is also discussed.

... 目前报道的制备Bi₂Se₃纳米片、纳米带的方法很多, 主要有溶剂热法^[16]、化学浴沉积^[17](CBD)、分子束外延法^[18,19](MBE)、机械剥离^[3]等 ...

2010

13.025

0.0

Nano Lett.. 2010, 10(6):2245–2250-null

Few-Layer Nanoplates of Bi₂Se₃ and Bi₂Te₃ with Highly Tunable Chemical Potential

Desheng Kong † , Wenhui Dang ‡ , Judy J. Cha † , Hui Li ‡ , Stefan Meister † , Hailin Peng * ‡ , Zhongfan Liu ‡ and Yi Cui * †

† Department of Materials Science and Engineering, Stanford University, Stanford, California 94305 ‡ Center for Nanochemistry, Beijing National Laboratory for Molecular Sciences (BNLMS), State Key Laboratory for Structural Chemistry of Unstable and Stable Species, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, People’s Republic of China * To whom correspondence should be addressed: hlpeng@pku.edu.cn (H.P.) and yicui@stanford.edu (Y.C.).

A topological insulator (TI) represents an unconventional quantum phase of matter with insulating bulk band gap and metallic surface states. Recent theoretical calculations and photoemission spectroscopy measurements show that group V−VI materials Bi 2 Se 3 , Bi 2 Te 3 , and Sb 2 Te 3 are TIs with a single Dirac cone on the surface. These materials have anisotropic, layered structures, in which five atomic layers are covalently bonded to form a quintuple layer, and quintuple layers interact weakly through van der Waals interaction to form the crystal. A few quintuple layers of these materials are predicted to exhibit interesting surface properties. Different from our previous nanoribbon study, here we report the synthesis and characterizations of ultrathin Bi 2 Te 3 and Bi 2 Se 3 nanoplates with thickness down to 3 nm (3 quintuple layers), via catalyst-free vapor−solid (VS) growth mechanism. Optical images reveal thickness-dependent color and contrast for nanoplates grown on oxidized silicon (300 nm SiO 2 /Si). As a new member of TI nanomaterials, ultrathin TI nanoplates have an extremely large surface-to-volume ratio and can be electrically gated more effectively than the bulk form, potentially enhancing surface state effects in transport measurements. Low-temperature transport measurements of a single nanoplate device, with a high-k dielectric top gate, show decrease in carrier concentration by several times and large tuning of chemical potential.

... 气相传输法(Vapor Transportation, VT)是近年来研究较多的一种方法, Kong^[20]、Zhao^[21]、Li^[22]等先后分别用VT法合成了Bi₂Se₃/Bi₂Te₃纳米片、纳米带 ...

2011

0.0

Angewandte Chemie International Edition. 2011, 50(44):10397-10401

One-Step Synthesis of Bismuth Telluride Nanosheets of a Few Quintuple Layers in Thickness

Dr. Yimin Zhao 1 ,Dr. Robert W. Hughes 1 ,Dr. Zixue Su 2 ,Prof. Wuzong Zhou 2 andProf. Duncan H. Gregory 1,*

1 WestCHEM, School of Chemistry, University of Glasgow, Glasgow G12 8QQ (UK) 2 EaStCHEM, School of Chemistry, University of St Andrews, St Andrews, Fife KY16 9ST (UK) * WestCHEM, School of Chemistry, University of Glasgow, Glasgow G12 8QQ (UK)

... 气相传输法(Vapor Transportation, VT)是近年来研究较多的一种方法, Kong^[20]、Zhao^[21]、Li^[22]等先后分别用VT法合成了Bi₂Se₃/Bi₂Te₃纳米片、纳米带 ...

2012

10.677

0.0

J. Am. Chem. Soc.. 2012, 134(14):6132–6135-null

Controlled Synthesis of Topological Insulator Nanoplate Arrays on Mica

Hui Li † , Jie Cao † , Wenshan Zheng † , Yulin Chen ‡ , Di Wu † , Wenhui Dang † , Kai Wang † , Hailin Peng * † , and Zhongfan Liu * †

† Center for Nanochemistry, Beijing National Laboratory for Molecular Sciences (BNLMS), State Key Laboratory for Structural Chemistry of Unstable and Stable Species, College of Chemistry and Molecular Engineering, Peking University , Beijing 100871, P. R. China ‡ Department of Physics and Clarendon Laboratory, University of Oxford , Parks Road, Oxford OX1 3PU, U.K. hlpeng@pku.edu.cn ; zfliu@pku.edu.cn

The orientation- and position-controlled synthesis of single-crystal topological insulator (Bi 2 Se 3 and Bi 2 Te 3 ) nanoplate arrays on mica substrates was achieved using van der Waals epitaxy. Individual ultrathin nanoplates with the lateral dimension up to ∼0.1 mm or uniform thickness down to 1–2 nm were produced. Single-Dirac-cone surface states of nanoplate aggregates were confirmed by angle-resolved photoemission spectroscopy measurements. The large-grain-size, single-crystal nanoplate arrays grown on mica can act as facile platforms for a combination of spectroscopy and in situ transport measurements, which may open up new avenues for studying exotic physical phenomena, surface chemical reactions, and modification in topological insulators.

... 气相传输法(Vapor Transportation, VT)是近年来研究较多的一种方法, Kong^[20]、Zhao^[21]、Li^[22]等先后分别用VT法合成了Bi₂Se₃/Bi₂Te₃纳米片、纳米带 ...

2012

4.814

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J. Phys. Chem. C. 2012, 116(5):3737–3746-null

Phase Transformation of Alternately Layered Bi/Se Structures to Well-Ordered Single Crystalline Bi₂Se₃ Structures by a Self-Organized Ordering Process

Tae-Hyeon Kim † , Ju Heyuck Baeck † , Hyejin Choi † , Kwang-Ho Jeong † , Mann-Ho Cho * † , B. C. Kim ‡ , and K. T. Jeong ‡

† Institute of Physics and Applied Physics, Yonsei University , Seoul 120-749, Korea ‡ Memory Division, Samsung Semiconductor R & D Center , Hwasung 445-701, Korea *E-mail: mh.cho@yonsei.ac.kr .

Multilayer films composed of alternating layers of Bi and Se—[Bi(4.55 Å)/Se(6.82 Å)] n (Bi4Se6), [Bi(6.13 Å)/Se(12.26) Å] n (Bi6Se12), and [Bi(4.86 Å)/Se(18.46 Å)] n (Bi4Se18)—were fabricated by controlling the layer thickness at the atomic scale using thermal evaporation techniques. After annealing treatment, the Bi4Se18 alternately layered film shows a single phase of Bi 2 Se 3 rhombohedral crystalline structure with the characteristic density of single crystal Bi 2 Se 3 , whereas the Bi6Se12 and Bi4Se6 films show locally disordered Bi 2 Se 3 crystalline structure. The effectively controlled layered structure in the as-grown Bi4Se18 film enhances the Bi–Se chemical bonding state. The formation of a layered crystalline structure during the annealing process increased as the thickness of Se increased. After interdiffusion and the crystallization process, alternately layered Bi4Se18 films become stable Bi 2 Se 3 single crystals with a continuous and uniform layered structure. Finally, in the Bi–Se system, atomically controlled multilayers with an optimized ratio of each unit layer can be transformed to a perfect single-crystalline structure on oxidized Si with an amorphous phase through a self-organized ordering process.

... 采用拉曼光谱法分析了Bi₂Se₃材料的组成和结构^[23], 图5为Bi₂Se₃块体、Bi₂Se₃纳米片和Bi₂Se₃纳米带的拉曼光谱图, 激发波长为514 nm, 光斑作用直径约1 #cod#x003bc ...

2010

13.025

0.0

Nano Lett.. 2010, 10(8):2870–2876-null

Epitaxial Heterostructures of Ultrathin Topological Insulator Nanoplate and Graphene

Wenhui Dang † , Hailin Peng † , Hui Li , Pu Wang and Zhongfan Liu *

Center for Nanochemistry, Beijing National Laboratory for Molecular Sciences (BNLMS), State Key Laboratory for Structural Chemistry of Unstable and Stable Species, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, People’s Republic of China * To whom correspondence should be addressed, zfliu@pku.edu.cn .,† These authors contributed equally to this work.

The authors present a van der Waals epitaxy of high-quality ultrathin nanoplates of topological insulator Bi 2 Se 3 on a pristine graphene substrate using a simple vapor-phase deposition method. Sub-10-nm-thick nanoplates of layered Bi 2 Se 3 with defined orientations can be epitaxially grown on a few-layer pristine graphene substrate. We show the evolution of Raman spectra with the number of Bi 2 Se 3 layers on few-layer graphene. Bi 2 Se 3 nanoplates with a thickness of three quintuple-layers (3-QL) exhibit the strongest Raman intensity. Strain effects in the Bi 2 Se 3 /graphene nanoplate heterostructures is also studied by Raman spectroscopy. 1-QL and 2-QL Bi 2 Se 3 nanoplates experience tensile stress, consistent with compressive stress in single-layer and bilayer graphene substrates. Our results suggest an approach for the synthesis of epitaxial heterostructures that consist of an ultrathin topological insulator and graphene, which may be a new direction for electronic and spintronic applications.

... 表示面外振动模式(out-plane vibrational mode), 原子沿垂直于面方向振动^[24], 峰值高低反映了其振动强弱 ...

2011

13.025

0.0

Nano Lett.. 2011, 11(6):2407–2414-null

Raman Spectroscopy of Few-Quintuple Layer Topological Insulator Bi₂Se₃ Nanoplatelets

Jun Zhang † , Zeping Peng ‡ , Ajay Soni † , Yanyuan Zhao † , Yi Xiong § , Bo Peng † , Jianbo Wang § , Mildred S. Dresselhaus ∥⊥ , and Qihua Xiong * † #

† Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University , Singapore 637371 ‡ School of Physical Science and Technology, MOE Key Laboratory on Luminescence and Real-Time Analysis, Southwest University , Chongqing 400715, China § School of Physics and Technology, Center for Electron Microscopy and MOE Key Laboratory of Artificial Micro- and Nano-Structures, Wuhan University , Wuhan 430072, China ∥ Department of Physics and ⊥ Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States # Division of Microelectronics, School of Electrical and Electronic Engineering, Nanyang Technological University , Singapore 639798 *E-mail: Qihua@ntu.edu.sg .

We report on Raman spectroscopy of few quintuple layer topological insulator bismuth selenide (Bi 2 Se 3 ) nanoplatelets (NPs), synthesized by a polyol method. The as-grown NPs exhibit excellent crystalline quality, hexagonal or truncated trigonal morphology, and uniformly flat surfaces down to a few quintuple layers. Both Stokes and anti-Stokes Raman spectroscopy for the first time resolve all four optical phonon modes from individual NPs down to 4 nm, where the out-of-plane vibrational A 1g 1 mode shows a few wavenumbers red shift as the thickness decreases below ∼15 nm. This thickness-dependent red shift is tentatively explained by a phonon softening due to the decreasing of the effective restoring force arising from a decrease of the van der Waals forces between adjacent layers. Quantitatively, we found that the 2D phonon confinement model proposed by Faucet and Campbell cannot explain the red shift values and the line shape of the A 1g 1 mode, which can be described better by a Breit–Wigner–Fano resonance line shape. Considerable broadening (∼17 cm –1 for six quintuple layers) especially for the in-plane vibrational mode E g 2 is identified, suggesting that the layer-to-layer stacking affects the intralayer bonding. Therefore, a significant reduction in the phonon lifetime of the in-plane vibrational modes is probably due to an enhanced electron–phonon coupling in the few quintuple layer regime.

... Bi₂Se₃纳米带的峰值最强, 主要是纳米带较窄, 且厚度相对较小, 原子振动受到的限制作用最小, 极化率较高, 因此具有较大的振动强度^[25] ...

2012

13.025

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Nano Lett.. 2012, 12(3):1203–1209-null

Enhanced Thermoelectric Properties of Solution Grown Bi₂Te_3–xSe_x Nanoplatelet Composites

Ajay Soni † , Zhao Yanyuan † , Yu Ligen ‡ , Michael Khor Khiam Aik * ‡ , Mildred S. Dresselhaus § , and Qihua Xiong * † ∥

† Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University , Singapore 637371 ‡ Division of Manufacturing Engineering, School of Mechanical and Aerospace Engineering, Nanyang Technological University , Singapore 639798 § Department of Physics and Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States ∥ Division of Microelectronics, School of Electrical and Electronic Engineering, Nanyang Technological University , Singapore 639798 *E-mail: (M.K.K.A.) mkakhor@ntu.edu.sg ; (Q.X.) Qihua@ntu.edu.sg .

We report on the enhanced thermoelectric properties of selenium (Se) doped bismuth telluride (Bi 2 Te 3– x Se x ) nanoplatelet (NP) composites synthesized by the polyol method. Variation of the Se composition within NPs is demonstrated by X-ray diffraction and Raman spectroscopy. While the calculated lattice parameters closely follow the Vegard’s law, a discontinuity in the shifting of the high frequency (E g 2 and A 1g 2 ) phonon modes illustrates a two mode behavior for Bi 2 Te 3– x Se x NPs. The electrical resistivity (ρ) of spark plasma sintered pellet composites shows metallic conduction for pure Bi 2 Te 3 NP composites and semiconducting behavior for intermediate Se compositions. The thermal conductivity (κ) for all NP composites is much smaller than the bulk values and is dominated by microstructural grain boundary scattering. With temperature dependent electrical and thermal transport measurements, we show that both the thermoelectric power S (−259 μV/K) and the figure of merit ZT (0.54) are enhanced by nearly a factor of 4 for SPS pellets of Bi 2 Te 2.7 Se 0.3 in comparison to Bi 2 Te 3 NP composites. Tentatively, such an enhancement of the thermoelectric performance in nanoplatelet composites is attributed to the energy filtering of low energy electrons by abundant grain boundaries in aligned nanocomposites.

... 仔细观察还可发现, Bi₂Se₃纳米带的特征峰发生了红移(red shift), 约3~4 cm^-1, 可能是缺陷引起的声子限域效应, 使得能隙减小, 产生红移^[26] ...

2010

4.689

0.0

2013

0.0

physica status solidi (RRL) - Rapid Research Letters. 2013, 7(1‐2):15-25

Topological insulator nanostructures

Judy J. Cha 1 ,Kristie J. Koski 1 andYi Cui 1,2,*

1 Materials Science and Engineering, Stanford University, 476 Lomita Mall, Stanford, CA 94305, USA 2 Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA * Phone: 650 723 4613, Fax: 650 725 4034

... Bi₂Se₃是层状菱形斜六面体晶体结构, 在方向由组成为Se-Bi-Se-Bi-Se的一个个单元层组成^[28,29], 层内原子由很强的共价键连接, 而单元层之间靠很弱的范德华力连接 ...

2012

10.677

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J. Am. Chem. Soc. 2012, 134(33):13773–13779-null

Chemical Intercalation of Zerovalent Metals into 2D Layered Bi₂Se₃ Nanoribbons

Kristie J. Koski † , Colin D. Wessells † , Bryan W. Reed ‡ , Judy J. Cha † , Desheng Kong † , and Yi Cui * † §

† Department of Materials Science and Engineering, Stanford University , Stanford, California 94305, United States ‡ Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory , 7000 East Avenue, Livermore, California 94550, United States § SLAC National Accelerator Laboratory, Stanford Institute for Materials and Energy Sciences , 2575 Sand Hill Road, Menlo Park, California 94025, United States yicui@stanford.edu

We have developed a chemical method to intercalate a variety of zerovalent metal atoms into two-dimensional (2D) layered Bi 2 Se 3 chalcogenide nanoribbons. We use a chemical reaction, such as a disproportionation redox reaction, to generate dilute zerovalent metal atoms in a refluxing solution, which intercalate into the layered Bi 2 Se 3 structure. The zerovalent nature of the intercalant allows superstoichiometric intercalation of metal atoms such as Ag, Au, Co, Cu, Fe, In, Ni, and Sn. We foresee the impact of this methodology in establishing novel fundamental physical behaviors and in possible energy applications.

2013

38.597

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... 由于各向异性的结构特征, Bi₂Se₃不同面之间结合能不同, 因此沿不同方向的生长速率不同^[30] ...

... 可以推测, 如果进一步降低形核温度(能量仍足以克服结合能), 很可能会生成 Bi₂Se₃纳米线, 这一假设也在Yan等^[30]的研究中得到验证 ...