Issue 70, 2020

High quality N-polar GaN films grown with varied V/III ratios by metal–organic vapor phase epitaxy

Abstract

We studied the growths and characterizations of N-polar GaN films grown with constant and varied V/III ratios in high-temperature (HT) GaN growth on offcut c-plane sapphire substrates by metal–organic vapor phase epitaxy. It is found that growth with a constantly low V/III ratio resulted in a high crystallinity but a rough surface and a high oxygen concentration, whereas growth with a high V/III ratio led to a smooth surface but a high carbon concentration and a degraded crystallinity. The overall quality of the N-polar GaN epilayer cannot be effectively improved simply by tuning the V/III ratio. The growth with varied V/III ratios was conducted by lowering the V/III ratio in the initial HT-GaN growth and keeping the V/III ratio constantly high in the subsequent growth. Such a change of V/III ratio resulted in a 3D-to-2D like growth mode transition during the early stage of HT-GaN growth which helped reduce threading dislocations and suppress impurity incorporation. By optimizing the nucleation temperature and the thickness of the initial low-V/III-ratio layer, the minimum full-widths at half-maximum of (00[2 with combining macron])/(10[2 with combining macron]) rocking curves obtained were 288/350 arcsec and the oxygen concentration was reduced significantly from 1.6 × 1018 cm−3 to 3.7 × 1017 cm−3 while keeping a hillock-free smooth surface morphology. The overall quality of the N-polar GaN films was considerably improved. We believe that this simple, yet effective growth technique has great application prospects for high-performance N-polar GaN-based electron devices.

Graphical abstract: High quality N-polar GaN films grown with varied V/III ratios by metal–organic vapor phase epitaxy

Supplementary files

Article information

Article type
Paper
Submitted
14 Sep 2020
Accepted
23 Nov 2020
First published
27 Nov 2020
This article is Open Access
Creative Commons BY-NC license

RSC Adv., 2020,10, 43187-43192

High quality N-polar GaN films grown with varied V/III ratios by metal–organic vapor phase epitaxy

C. Li, K. Zhang, Qiaoyu Zeng, X. Yin, X. Ge, J. Wang, Q. Wang, C. He, W. Zhao and Z. Chen, RSC Adv., 2020, 10, 43187 DOI: 10.1039/D0RA07856E

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