中文摘要：

研究了等离子体刻蚀Al N缓冲层对硅衬底N极性n-Ga N表面粗化行为的影响.实验结果表明,表面Al N缓冲层的状态对N极性n-Ga N的粗化行为影响很大,采用等离子体刻蚀去除一部分表面Al N缓冲层即可以有效提高N极性n-Ga N在KOH溶液中的粗化效果,Al N缓冲层未经任何刻蚀处理的样品粗化速度过慢,被刻蚀完全去除Al N缓冲层的样品容易出现粗化过头的现象.经X射线光电子能谱分析可知,等离子体刻蚀能够提高样品表面Al N缓冲层Al2p的电子结合能,使得样品表面费米能级向导带底靠近,原子含量测试表明样品表面产生了大量的N空位,N空位提供电子,使得材料表面费米能级升高,这降低了KOH溶液和样品表面之间的肖特基势垒,从而有利于表面粗化的进行.通过等离子体刻蚀掉表面部分Al N缓冲层,改善了N极性n-Ga N在KOH溶液中的粗化效果,明显提升了对应发光二级管器件的出光功率.

英文摘要：

Light extraction efficiency of thin-film Ga N-based light-emitting-diode（LED） chip can be effectively improved by surface roughening. The film transfer is an indispensable process in the manufacture of thin-film LED chip, which means transferring the LED film from the growth substrate to a new substrate, and then removing the growth substrate. After the growth substrate is removed, the buffer layer is used to cushion the mismatch between the substrate and the n-Ga N exposed, which has a significant influence on the roughening behavior of n-Ga N. Unlike the Ga N buffer layer grown on sapphire substrate, Al N buffer layer is usually used when n-Ga N is grown on Si substrate. In this paper, the surface treatment of the Al N buffer layer by reactive ion etching（RIE） is used to improve the surface roughening effect of N-polar n-Ga N grown on the silicon substrate in the hot alkali solution（85？C, 20% KOH mass concentration of solution）, and the mechanism of the influence of the surface treatment on the roughening behavior is discussed by X-ray photoelectron spectroscopy（XPS） and other advanced methods. The degree of etching surface Al N buffer layer is detected by energy dispersive spectrometer（EDS）, the sample surface state after RIE etching is analyzed by XPS, the morphology of the surface roughening is observed by scanning electron microscope（SEM） and the effect of surface roughening on the optical power of LED devices is verified by the photoelectric performance test. The EDS results show that the Al N buffer layer remains after RIE etching 10–30 min and the Al N disappears after RIE etching for 40 min. The SEM results show that surface states of Al N buffer layer have a great influence on the roughening behavior of n-Ga N in KOH solution.The sample with part of Al N buffer layer has a good roughening effect and proper size hexagonal pyramid distributing uniformly. In addition, the rate of coarsening is too fast for the samples with Al N buffer layer completely removed, while the rate is