重掺杂n型GaN材料特性研究

Investigation on Characteristics of Heavy Si-doping GaN Grown by MOCVD

摘要:

采用金属有机化合物气相外延方法制备了不同SiH4流量下重掺杂n型GaN材料,研究发现在SiH4流量为20cm3/min时样品获得较高的电子浓度,达到6.4×1019 cm-3,同时材料的结晶质量较好。光荧光测试发现重掺杂使GaN材料的杂质能带进入导带形成带尾态,使带边峰变得不尖锐,并且发现SiH4流量以及材料的刃位错密度与黄光带发光有关。采用Delta掺杂方式生长的重掺杂样品,样品表面粗糙度降低,晶体质量明显改善,但黄光带发光强度增强。缺陷选择性腐蚀研究发现Delta掺杂方式主要通过降低螺位错密度来改善晶体的质量。

Abstract:

Heavy Si-doping GaN on sapphire under different SiH4 flux was grown by metalorganic chemical vapor deposition (MOCVD). Hall effect measurement results show that electron concentration of the sample in 20cm3/min SiH4 gets to a high level of 6.4×1019cm-3, and the crystallization quality measured by XRD is better at the same time. The photoluminescence results indicate that heavy Si-doping condition makes impurity band enter in conduction band, which makes edge-band peak not sharp, and the SiH4 flux has an effect on the density of edge dislocation and yellow luminescence. When the doping way changes to periocic Si delta-doping, the samples surface roughness reduces and its crystallization quality improves obiously, but the intensity of yellow luminescence enhances. Defect-selective etching demonstates that reducing the screw dislocation density can improve the crystallization quality for Delta-doping.