InGaN/GaN多量子阱蓝光LED的p-GaN盖层的MOCVD生长研究

利用金属有机物化学气相淀积（MOCVD）生长了InGaN／GaN多量子阱（MQW）蓝光发光二极管（LED），研究了不同Cp2Mg流量下生长的p-GaN盖层对器件电学特性的影响。结果表明，随着Cp2Mg流量的提高，漏电流升高，并且到达一临界点会迅速恶化；正向压降则先降低，后升高。进而研究相同生长条件下生长的p-GaN薄膜的电学特性、表面形貌及晶体质量，结果表明，生长p-GaN盖层时，Cp2Mg流量过低，盖层的空穴浓度低，电学特性不好；Cp2Mg流量过高，则会产生大量的缺陷，盖层晶体质量与表面形貌变差，使得空穴浓度降低，电学特性变差。因此，生长p-GaN盖层时，为使器件的正向压降与反向漏电流均达到要求，Cp2Mg流量应精确控制。

Investigations of p-GaN cap layers of InGaN/GaN MQW Blue LEDs grown by MOCVD

InGaN/GaN MQW blue light emitting diode(LED) structures whose p-GaN cap layers were grown with various flow rates of Cp_2Mg and p-GaN films with the same growth conditions were grown by MOCVD.The LEDs were fabricated and characterized by I-V measurement in order to investigate the effects of this varied growth condition on the electrical character of the devices.As the Cp_2Mg flow rate increased,the forward voltage of the LEDs decreased at first and then increased at a certain Cp_2Mg flow rate,and the leakage current increased without discontinuity.It was found that low Cp_2Mg flow rate can lead to low hole concentration and poor electrical property of the p-GaN cap layer,but high Cp_2Mg flow rate made the situation even worse,the surface morphology and crystallinity of the films become rough and worse.This was responsible for the changes of the electrical character of the LEDs.