MOCVD生长InGaN/AlGaN双异质结构与GaN过渡层的工艺与特性

Processing and Characteristics of InGaN/AlGaN Double Heterojunction Structure and of GaN Buffer Layer Grown by MOCVD Techniques

评述利用MOCVD技术在α Al2 O3 衬底上生长GaN薄膜及InGaN/AlGaN双异质结 (DH)结构的工艺与特性 ;从表面动力学观点着重讨论了GaN过渡层MOCVD生长条件 (温度、气流束源等 )对表面形貌、结晶形态、掺杂及其光电性能的影响。分析表明 ,GaN薄膜生长速率主要依赖于反应炉温度 ,气流束源摩尔流量速率。若生长温度太高 ,引起PL发光谱峰向长波侧移动 ;GaN缓冲层生长温度必须控制在 5 5 0℃。高的Ⅴ /Ⅲ双气束流比率能够抑制GaN发光谱中 5 5 0nm辐射峰产生。为了获得高质量 p AlGaN、GaN层 ,控制生长温度和以Cp2 Mg为杂质源的Mg受主掺杂量 ,并在N2 气氛中 80 0℃快速退火 。

The processing and characteristics of InGaN/AlGaN double heterojunction (DH) structure and of GaN epilayer grown on the α Al 2O 3 substrate by means of metalorganic chemical vapor deposition (MOCVD) technique are reviewed. The important effect of the MOCVD growth condition (temperature, gas source flow etc.) of the GaN buffer layer on the surface morphology, crystallinity and opto electronic properties is discussed from the point of view of the surface dynamics. The analysis indicates that the growth rate of GaN film is dependent chiefly on the furnace temperature, the molar flow rate of the gas sources. As increasing the temperature, the PL peak shifts to longer wavelength. The growth temperature of the GaN buffer layer must be controlled at 550 ℃. The high ratio of Ⅴ/Ⅲ gas source flows can restrain the radiant intensity about 550 nm in the GaN photoluminescence spectrum. To obtain a good epilayer film with high radiation rate the Cp 2Mg source is used as the Mg acceptors doping in p AlGaN and p GaN compound semiconductor. It is noticed that,the epitaxial temperature and time, Mg doping dose should be optimally controlled, furthermore, the sample is annealed rapidly at 800℃ under the N 2 gas flow. In fact, above mentioned efforts have been made importantly on the lattice microstructure improvement and the increase of luminous intensity for the InGaN/AlGaN DH LED.