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在等离子增强化学气相沉积法(PECVD)沉积SiO2和SiNX掩蔽层过程中,分解等离子体中浓度较高的H原子使Mg-受主钝化,同时在p-GaN材料表面发生反应形成浅施主特性的NV+空位。高能量离子轰击造成的材料深能级缺陷增多以及沉积形成致密的SiO2和SiNX材料,阻碍了H原子向外扩散,使H原子在Ni/Au电极与p-GaN的界面处聚集,造成p-GaN近表面附近区域Mg-H络合物密度的提高,空穴浓度急剧下降,导致Ni/Au透明电极I-V特性严重恶化。选择较低的射频功率(15W,13.56MHz)沉积模式,经过适当的退火,可以减小沉积SiO2过程对p-GaN的影响。
During PECVD deposition of SiO 2 and SiNX masking layers, high-concentration H atoms in the plasma are decomposed to passivate the Mg-acceptor while a shallow donor characteristic is formed on the surface of the p-GaN material NV + slot. The increase of deep level defects caused by high-energy ion bombardment and the deposition of dense SiO2 and SiNX materials hinder the outward diffusion of H atoms and the accumulation of H atoms at the interface of Ni / Au electrode and p-GaN, resulting in the formation of p- The density of Mg-H complex in the vicinity of the near surface of GaN is increased, and the concentration of the hole is drastically decreased, resulting in a serious deterioration of the IV characteristics of the Ni / Au transparent electrode. The lower RF power (15W, 13.56MHz) deposition mode is chosen to reduce the effect of deposition of SiO2 on p-GaN with proper annealing.