PECVD法制备高结晶GaN薄膜及其光电响应性能  

PECVD-prepared high-quality GaN films and their photoresponse properties

作　　者：梁琦 杨孟骐 张京阳 王如志[1] Liang Qi;Yang Meng-Qi;Zhang Jing-Yang;Wang Ru-Zhi(Key Laboratory of Advanced Functional Materials,Education Ministry of China,Institute of New Energy Materials and Technology,Faculty of Materials and Manufacturing,Beijing University of Technology,Beijing 100124,China)

机构地区：[1]北京工业大学材料与制造学部,新能源材料与技术研究所,新型功能材料教育部重点实验室,北京100124

出　　处：《物理学报》2022年第9期291-301,共11页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11774017)资助的课题。

摘　　要：采用一种简单、绿色、低成本的等离子增强化学气相沉积(PECVD)法,在950℃下成功制备了高结晶质量的GaN薄膜.为了提高GaN薄膜结晶质量和弄清GaN薄膜光响应机制,研究了GaN缓冲层制备温度对GaN薄膜结晶质量和光电性能的影响.研究表明,随着GaN缓冲层制备温度的增加,GaN薄膜的结晶质量先提高后降低,在缓冲层温度为875℃时,结晶质量最高,此时计算得出的总位错密度为9.74×10^(9)cm^(2),载流子迁移率为0.713 cm^(2)/(V·s).经过退火后,GaN薄膜的总位错密度降低到7.38×10^(9)cm^(2),载流子迁移率增大到43.5 cm^(2)(V·s),此时GaN薄膜光响应度为0.20 A/W,光响应时间为15.4 s,恢复时间为24 s,可应用于紫外光探测器.通过Hall测试和X射线光电子能谱仪分析得出,GaN薄膜内部存在着N空位、Ga空位或O掺杂,它们作为深阱能级束缚和复合光生电子和空穴,使得光响应度与偏压呈抛物线关系;另外,空位和O掺杂形成的深阱能级也是导致GaN薄膜的光电流响应和恢复缓慢的根本原因.In this study,the high-quality GaN films are prepared by a simple,green and low-cost plasma enhanced chemical vapor deposition(PECVD)method at 950℃.with Ga;O;and N;serving as a gallium source and a nitrogen source,respectively.In order to improve the crystal quality of GaN films and ascertain the photoresponse mechanism of GaN films,the effect of the preparation temperature of GaN buffer layer on the crystal quality and photoelectric properties of GaN thin films are investigated.It is indicated that with the increase of the buffer temperature of GaN films,the crystal quality of GaN films first increases and then decreases,and the highest crystal quality is obtained at 875℃.When buffer layer temperature is 875℃,the calculated total dislocation density is 9.74×10^(9)cm^(2),and the carrier mobility is 0.713 cm^(2)·V^(-1)·s^(-1).The crystal quality of GaN film after being annealed is improved.The total dislocation density of GaN film decreases to 7.38×10^(9)cm^(2),and the carrier mobility increases to 43.5 cm^(2)·V^(-1)·s^(-1).The UV-Vis absorption spectrum results indicate that the optical band gap of GaN film is 3.35 eV.The scanning electron microscope(SEM)results indicate that GaN film(buffer layer temperature is 875℃)has smooth surface and compact structure.The Hall and X-ray photoelectron spectroscopy(XPS)results indicate that there are N vacancies,Ga vacancies or O doping in the GaN film,which act as deep level to capture photogenerated electrons and holes.With the bias increasing,the photoresponsivity of the GaN film photo detector gradually increases and then reaches a saturation value.This is due to the deep levels produced by vacancy or O doping.In addition,photocurrent response and recovery of GaN film are slow,which is also due to the deep levels formed by vacancy or O doping.At 5-V bias,the photoresponsivity of GaN film is 0.2 A/W,rise time is 15.4 s,and fall time is 24 s.Therefore,the high-quality GaN film prepared by the proposed green and low-cost PECVD method present a strong potential

关 键 词：GAN薄膜 等离子增强化学气相沉积法 结晶质量 光响应度 光响应机理 

分 类 号：TB383.2[一般工业技术—材料科学与工程]