Abstract

We investigated the effects of different thermal treatment conditions on the surface and internal residual strains of bulk GaN grown by hydride vapor phase epitaxy (HVPE). Thermal annealing was performed at 700–1000 °C for 1–5 h in nitrogen atmosphere. The GaN was characterized by atomic force microscopy, energy dispersive spectrometry, X-ray photoelectron spectroscopy, Raman spectroscopy, and by high-resolution X-ray diffractometer. The experimental results demonstrated that thermal decomposition and oxidation occurred on the surface of GaN when exposed to heat over a long time, or even at a low temperature, as compared to thermal decomposition of GaN in ambient nitrogen. The internal residual stress of GaN was relaxed most effectively when annealing at 900 °C for 3 h, and it was confirmed that the crystal quality is best under this condition. We also confirmed that the effect of annealing was extremely beneficial because native oxide impurities were removed most effectively in this condition. However, Ga metal or oxide could formed due to the occurrence of slight thermal decomposition on the surface.

Graphic Abstract

中文翻译：

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HVPE生长GaN衬底在不同热退火条件下表面形貌和残余应力的变化研究。

摘要

我们研究了不同热处理条件对氢化物气相外延（HVPE）生长的块状GaN的表面和内部残余应变的影响。在氮气氛中于700–1000°C进行热退火1-5小时。GaN的特征在于原子力显微镜，能量色散谱，X射线光电子能谱，拉曼光谱和高分辨率X射线衍射仪。实验结果表明，与环境氮气中GaN的热分解相比，长时间或什至在低温下暴露于GaN时，GaN的表面会发生热分解和氧化。当在900°C下退火3 h时，GaN的内部残余应力最有效地松弛，并且可以确认在此条件下晶体质量最佳。我们还证实了退火的效果是非常有益的，因为在这种条件下天然氧化物杂质被最有效地去除了。然而，由于在表面上发生轻微的热分解，可能形成Ga金属或氧化物。

图形摘要