摘要
研究了碳杂质对p-GaN的补偿作用。采用金属有机化学气相沉积法生长GaN∶Mg材料,实验发现,当生长温度从1000℃提高到1050℃时,p-GaN的电阻率减小,空穴浓度增大。通过光致发光测试,发现随着生长温度的升高,尽管p-GaN的电阻率减小,但是Mg杂质的自补偿效应增强。进一步结合二次离子质谱测试,发现高温生长的p-GaN材料中碳杂质浓度更低,碳杂质在p-GaN中可能形成施主,从而补偿受主,增大p-GaN的电阻率。因此,在p-GaN中,碳杂质补偿相对于Mg杂质自补偿具有更重要的作用,抑制碳杂质对p型掺杂p-GaN非常重要。
Objective Gallium nitride(GaN) and its ternary alloys have drawn considerable attention because of their broad applications and promising market prospects for light-emitting devices. p-type doped GaN is an important part of GaN-based optoelectronic device structure. However, the applications of p-GaN are often limited by the low hole concentration and high resistivity. Until now, only Mg has been successfully employed as an effective and practical acceptor impurity in GaN for achieving useful p-type conduction. Post-growth treatment, such as thermal annealing, is required to activate the Mg acceptors in GaN in case of layers grown via metal-organic chemical vapor deposition(MOCVD). Further, there is convincing evidence that hydrogen passivates Mg acceptors in the as-grown state of the materials. An appropriate Mg doping concentration is required for obtaining high-quality GaN. The usage of a considerably high or low Mg doping concentration does not allow for a high hole concentration because of the self-compensation effect associated with heavy Mg doping. In addition, the dislocation density and the concentration of unintentionally doped impurities(e.g., carbon and oxygen) have an important effect on the resistivity of p-GaN. Overall, the compensation mechanisms and functions of the p-doped GaN and AlGaN materials must be clarified for their further development.Methods A series of Mg-doped p-GaN films was grown in a vertical MOCVD system under different growth temperatures.An Aixtron 3×2 MOCVD system was used for growing p-GaN films.A 20-nm thick GaN buffer layer was initially grown at 540℃on a sapphire substrate.Then,a 2-μm thick unintentionally doped GaN layer was grown by increasing the temperature to 1060 ℃.Subsequently,a series of 0.7-μm thick Mg-doped GaN layers was grown at 1000--1050 ℃.Each sample was annealed at 800℃for 3 min under the same nitrogen environment for activating the Mg acceptors.Trimethylgallium(TMGa),ammonia(NH3),and Cp2Mg were used as sources of Ga,N,and Mg,respectively,when us
作者
吴昕宁
刘昭阳
刘明佳
赵云涛
齐浩然
周梅
沈慧星
赵德刚
Wu Xinning;Liu Zhaoyang;Liu Mingjia;Zhao Yuntao;Qi Haoran;Zhou Mei;Shen Huixing;Zhao Degang(Department of Applied Physics,College of Science,China Agricultural University,Beijing 100083,China;State Key Laboratory of Integrated Optoelectronics,Institute of Semiconductors,Chinese Academy of Sciences,Beijing 100083,China)
出处
《中国激光》
EI
CAS
CSCD
北大核心
2021年第13期72-77,共6页
Chinese Journal of Lasers
基金
国家自然科学基金(61974162,61474142)。
关键词
材料
P-GAN
补偿作用
碳杂质
二次离子质谱
materials
p-GaN
compensation effect
carbon impurities
secondary ion mass spectroscopy
