MOVPE低温生长的n型GaN电学特性研究  

Study on electrical properties of n-GaN grown at low temperature by metal-organic vapor phase epitaxy

作　　者：汪莱[1] 张贤鹏[1] 席光义[1] 赵维[1] 李洪涛[1] 江洋[1] 韩彦军[1] 罗毅[1] 

机构地区：[1]集成光电子学国家重点实验室,清华信息科学与技术国家实验室,清华大学电子工程系,北京100084

出　　处：《物理学报》2008年第9期5923-5927,共5页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:60536020,60390074);国家重点基础研究发展计划(973)(批准号:2006CB302801,2006CB302804,2006CB302806,2006CB921106);国家高技术研究发展计划(863)(批准号:2006AA03A105);北京市科学技术委员会重点项目(批准号:D0404003040321)资助的课题~~

摘　　要：系统研究了采用金属有机物化学气相外延方法在740℃和900℃条件下生长的n型GaN的电学特性.电化学电容-电压测试表明,在低温条件下采用三乙基镓作为Ga源生长有利于降低非故意掺杂n型GaN的背景杂质浓度.另外,对重掺Si的n型GaN的霍耳效应测试表明,随着Si掺杂浓度增大,电子浓度相应线性增大,表现出杂质带导电特性,而迁移率则相应减小.同时,原子力显微镜测试和X射线衍射测试均表明生长温度和掺杂浓度对外延材料的表面形貌和晶体质量有影响,特别是在高掺杂浓度的情况下,样品的表面形貌恶化更严重.在所研究的Si掺杂浓度范围内,在氧气中退火前后所有样品的电子迁移率基本不变,而Si掺杂浓度高于6×1019cm-3的样品在氧气中退火后电子浓度会下降,表明对低温生长的重掺杂n型GaN,热处理的过程有助于Si原子取代N原子形成受主而产生补偿施主的作用.Electrical properties of n-GaN grown at 740℃ and 900℃ by metal-organic vapor phase epitaxy were studied in detail. According to the electrochemical capacitance-voltage measurement, it is helpful to reduce the background impurity concentration in unintendedly-doped n-GaN grown at low temperature using TEGa as Ga precursor rather than TMGa. The results of Hall effect measurement of heavily Si-doped n-GaN show that, as Si concentration increases, the electron concentration increases almost linearly, which exhibits the dopant band conducting effect, while the electron mobility decreases. Atomic force microscope and X-ray diffraction measurements show that the surface morphology and crystal quality of most samples were determined by growth temperature and Si doping level. The surface morphology of all samples had a visible change only when the doping level was much higher at the same growth temperature. On the other hand, after the samples were annealed in oxygen, the electron mobility of all the samples remained almost constant, but the electron concentration decreased when the Si concentration was larger than 6 × 10^19cm^-3. This result indicates that in the heavily Si-doped n-GaN grown at low temperature, the annealing process could result in the formation of acceptors due to the replacement of N by Si atoms.

关 键 词：N型GAN 电子浓度 迁移率 

分 类 号：O472.4[理学—半导体物理]