As-grown Surface Morphologies of SiC Single Crystals Grown by PVT Method

doi:10.15541/jim20170507

Abstract

Abstract:

As-grown surface of single crystal can reflect abundant information including crystal growth mechanism and defect distribution of the single crystal after growth. The as-grown surface morphologies of 4H-SiC and 6H-SiC single crystals were observed and measured by laser confocal microscope DIC splicing technique and atomic force microscope (AFM). It is found that as-grown 4H-SiC surface tends to appear hexagonal growth steps, while the as-grown 6H-SiC surface tends to appear circular growth steps. Based on Jackson model and thermodynamics theory, Jackson factors of the 4H-SiC and 6H-SiC single crystals are calculated to be 33.15 and 31.87, respectively. Therefore, the surface morphology difference between 4H-SiC and 6H-SiC is caused by the roughness of growth interface and crystal growth temperature. The micropipe on the as-grown surface is the origin of growth steps and multiple micropipes on the as grown surface were measured by AFM. Their diameters are in the range of 760 nm- 6.0 μm, and the corresponding absolute values of Burgers vector are in the range of 5c-14c. Through structure characterization and statistical analysis, the values of micropipe diameters divided by squares of the burgers vectors (D/B²) are in the range of 11.1 nm^-1-23.6 nm^-1, which means the structure data of these micropipes obtained by AFM cannot strictly obey the Frank theory.

Key words: SiC, as-grown surface, structure of micropipes

CLC Number:

O766

CUI Ying-Xin, HU Xiao-Bo, XU Xian-Gang. As-grown Surface Morphologies of SiC Single Crystals Grown by PVT Method[J]. Journal of Inorganic Materials, 2018, 33(8): 877-882.

Figures/Tables 9

Fig. 1 Typical as-grown surface morphology of 4H-SiC

Fig. 2 Surface morphologies of the other as-grown 4H-SiC single crystal

Fig. 3 Typical as-grown surface morphology of 6H-SiC

Fig. 4 Surface morphologies of the other as-grown 6H-SiC single crystal

Fig. 5 AFM images showing typical micropipes on the facet of a 6H-SiC single crystal

Table 1 Enthalpy of SiC, Si, SiC2 as a function of temperature

Species	H₂₉₈	A	B	C	D	E	F	G	H
Si	0
SiC	718.96	7.970	1.06	-0.210	0.0138	0.73	171.470	62.757	172
SiC₂	614.46	17.314	-3.23	1.256	-0.1150	-1.24	138.586	73.640	147

Fig. 6 Three dimensional AFM image showing typical micropipes on the facet of a 6H-SiC single crystal

Fig. 7 Section image of the spiral step on the as-grown surface of single crystal

Table 2 Relationship between micropipe diameter and the screw type step height

Micropipe	1	2	3	4	5	6
Diameter/μm	3.1	4.5	2.5	2.5	2.6	2.6
The number of steps	2	7	5	3	2	1
Step height/nm	-12.0	9.2	-1.6	-11.1	-9.8	-11.1
	-1.9	1.6	-6.0	-2.1	-1.1
		1.3	-1.3	-2.2
		1.6	-1.6
		1.6	-1.9
		1.3
		1.6
B/nm	-9c	12c	-8c	-10c	-7c	-7c
(D/B²)/nm^-1	17.0	13.9	17.4	11.1	23.6	23.6

References 17

[1]	HIROYUKI MATSUNAMI.Technological breakthroughs in growth control of silicon carbide for high power electronic devices.Japanese Journal of Applied Physics, 2004, 43(10): 6835-6847.
[2]	KARL O DOHNKE, KARSTEN GUTH, NICOLAS HEUCK.History and recent developments of packaging technology for SiC power deveces.Materials Science Forum, 2016, 858: 1043-1048.
[3]	XUN QIAN, XUN BOYANG, LI ZUXIN.Application of SiC power electronic devices in secondary power source for aircraft.Renewable and Sustainable Energy Reviews, 2017, 70: 1336-1342.
[4]	ZHANG YU, CHEN HUI, CHOI GLORIA,et al. Nucleation mechanism of 6H-SiC inclusions inside 15R-SiC crystals. Journal of Electronic Materials, 2010, 39(6): 799-804.
[5]	MASATOSHI KANAYA, JUN TAKAHASHI, YUIHIRO FUJIWARA,et al. Controlled sublimation growth of single crystalline 4H-SiC and 6H-SiC and identification of polytypes by X-ray diffraction.Appl. Phys. Lett, 1991, 58(1): 56-58.
[6]	KIM JUN GYU, JEONG JIN HWAN, KIM YOUNGHEE,et al. Evaluation of the change in properties caused by axial and radial temperature gradients in silicon carbide crystal growth using the physical vapor transport method.Acta Materialia, 2014, 77: 54-59.
[7]	STEINK R A, LANIG P.Control of polytype formation by surface energy effects during the growth of SiC monocrystals by the sublimation method.Journal of Crystal Growth, 1993, 131(71): 71-74.
[8]	NORBERT SCHULZE, DONOVAN L BARRETT, GERHARD PENSL,et al. Near-thermal equilibrium growth of SiC by physical vapor transport.Materials Science and Engineering B, 1999, 61-62: 44-47.
[9]	STRAUBINGER T L, BICKERMANN M, HOFMANN D,et al. Stability criteria for 4H-SiC bulk growth.Materials Science forum, 2001, 53-356: 25-28.
[10]	王文魁, 王继扬, 赵珊茸. 晶体形貌学.武汉: 中国地质大学出版社, 2001: 1-5.
[11]	KAZUMA ETO, HIROMASA SUO, TOMOHISA KATO,et al. Growth of p-type 4H-SiC single crystals by physical vapor transport using aluminum and nitrogen co-doping.Journal of Crystal Growth, 2017, 470: 154-158.
[12]	NORIHIRO HOSHINO, ISAHO KAMATA, YUICHIRO TOKUDA,et al. Fast growth of n-type 4H-SiC bulk crystal by gas-source method.Journal of Crystal Growth, 2017, 478: 9-16.
[13]	FRANK F C.Capillary equilibria of dislocated crystals.Acta Cryst., 1951, 4: 497-501.
[14]	SANDEEP MAHAJAN, ROKADE M Y, ALI S T,et al. Investigation of micropipe and defects in molten KOH etching of 6H n-silicon carbide single crystal.Materials Letters, 2013, 101: 72-75.
[15]	刘全坤, 祖方遒, 孙国雄, 等. 材料成形基本原理.北京: 机械工业出版社, 2009: 67-71.
[16]	DONG JIE, LIU ZHE, XU XIANGANG,et al. Investigation on the thermodynamics and kinetics of the growth of SiC single crystal.Journal of Synthetic Crystals, 2004, 33(3): 283-287.
[17]	HEINDL J, DORSCH W, STRUNK H P.Dislocation content of micropipes in SiC.Physical Review Letters, 1998, 80(4): 740-741.