无机材料学报

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高温退火对PVT法生长的AlN晶体质量的影响

俞瑞仙, 王国栋, 王守志, 胡小波, 徐现刚, 张雷   

  1. 山东大学 新一代半导体材料研究院,晶体材料国家重点实验室,济南 250100
  • 收稿日期:2022-08-13 修回日期:2022-10-09
  • 作者简介:俞瑞仙(1987-), 男, 博士研究生. E-mail: yuruixian0001@126.com

Effect of High-temperature Annealing on AlN Crystal Grown by PVT Method

YU Ruixian, WANG Guodong, WANG Shouzhi, HU Xiaobo, XU Xiangang, ZHANG Lei   

  1. Institute of Novel Semiconductors, State Key laboratory of Crystal Material, Shandong University, Jinan 250100, China
  • Received:2022-08-13 Revised:2022-10-09
  • About author:YU Ruixian (1987-), male, PhD candidate. E-mail: yuruixian0001@126.com
  • Supported by:
    National Natural Science Foundation of China (51872164, 52202265); Shenzhen Science and Technology Program (JCYJ20210324141607019)

摘要: 在PVT法生长AlN晶体的过程中,很难保持理想的热力学平衡条件,不可避免地会产生晶体缺陷。高温退火技术在提高晶体完整性方面十分有效而受到了广泛的关注,关于PVT法生长的AlN晶体的高温退火研究却鲜有报道。本工作在N2气氛环境下对PVT法生长的AlN晶片进行高温退火研究。为了评价AlN在退火前后的晶体质量和结构变化情况,进行了高分辨率X射线衍射(HRXRD)、拉曼光谱分析。通过室温光致发光(PL)和吸收光谱对AlN晶体的光学性质方面与杂质相关的带隙变化情况进行了表征。AlN晶体质量在1400~1800 ℃退火后显著提高,在1400 ℃退火后,(10-12)平面的X射线摇摆曲线的半峰宽FWHM从104.04 arcsec降低到79.92 arcsec。随着退火温度的升高,吸收性能明显增强,带隙增大,说明退火工艺有利于提高AlN晶体的质量。二次离子质谱(SIMS)结果表明,退火过程降低了C杂质,从而导致AlN晶体的带隙增加,这与光吸收结果一致。

关键词: 高温退火技术, AlN晶体, C杂质, 带隙

Abstract: In the process of PVT growth of AlN crystals, it is difficult to maintain ideal thermodynamic equilibrium conditions, thus crystal defects are inevitably generated. High temperature annealing technology has received much attention due to their effectiveness in improving crystal integrity. However, there are few reports on the high temperature annealing of AlN crystals grown by PVT method. In this paper, AlN samples grown by PVT method were annealed at high temperature in N2 atmosphere. In order to evaluate the crystalline quality and structural perfection of AlN before and after thermal annealing, high-resolution X-ray diffraction (HRXRD) and Raman spectrum were carried out. In addition, the impurity related band gap changes in the optical properties of AlN crystals were characterized by room temperature photoluminescence (PL) and absorption spectra. The crystal quality of these AlN crystals was significantly improved after annealing at 1400-1800 ℃. The full width at half maximum (FWHM) of the (10-12) plane X-ray rocking curve decreased from 104.04 to 79.92 arcsec after annealing at 1400 ℃. As the annealing temperature increases, the absorption was significantly enhanced and the band gap become larger, indicating that the annealing process is beneficial to improve the quality of AlN crystals. The results of secondary ion mass spectrometry (SIMS) show that the annealing process reduces the C impurity, resulting in an increase in the band gap of AlN crystal, which is consistent with the results of optical absorption.

Key words: high temperature annealing technology, AlN crystal, C impurities, bandgap

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