镁流量对MOCVD生长的P型GaN薄膜特性的影响

Influence of Mg Flow Rate on the Properties of P-GaN Films

利用MOCVD生长了不同Mg流量的P型GaN样品。研究了Mg流量对MOCVD生长的P型GaN薄膜的电学特性、表面形貌及晶体质量的影响。结果表明利用MOCVD制备高质量的P型GaN薄膜,Mg流量应处于一个合适的范围,Mg流量过低,薄膜的空穴浓度低,电学特性不好;Mg流量过高,则会产生大量的缺陷,晶体质量与表面形貌变差,Mg的活化率也降低,并且自补偿效应更加严重,最终使得空穴浓度降低,电学特性变差。将优化的条件应用于蓝光发光管的外延生长,并制备了器件,在20mA的注入电流下,输出功率为6.5mW,正向压降3V,反向击穿电压为20V。

P-GaN films were grown by MOCVD with various flow rates of Mg. Crystallographic and electrical properties of these P-GaN films were characterized by Hall technique and double crystal X-ray diffractometry （DCXRD）. The relation between the Mg flow rate and the property of P-GaN films was discussed. We found that low flow rate of Mg led to low hole concentration and poor electrical property, but high flow rate of Mg made the situation even worse. As the Mg flow rate increases, the surface morphology and crystallinity of the films become rough and worse due to more micro defects generated by doping Mg, the activation rate of Mg decreases, and the self-compensation effects is enhanced. The LED structure was grown using the optimum Mg flow rate. With 20 mA current injection, the output power of the LED （460 nm） was 6.5 mW, the Vf and Vr were 3.3 and 20 V,respectively.