掺杂对GaN晶体力学性能影响的研究

对GaN单晶力学性能的研究有助于解决其在生长、加工和器件应用中的开裂问题。本文围绕掺杂对GaN单晶力学性能的影响，通过纳米压痕法测试了不同掺杂类型(非掺、Si掺和Fe掺)GaN单晶的弹性模量和硬度，测试结果表明掺杂对GaN单晶的硬度有重要影响。Si掺、Fe掺GaN较非掺样品硬度有所提升，用重掺杂的氨热GaN单晶作为对照，也证明了这一结论。通过高分辨X射线衍射分析和原子力显微镜表征实验发现，晶体结晶质量、接触面积等因素对GaN单晶硬度的影响较小。对GaN表面纳米压痕滑移带长度和晶体晶格常数进行测试，结果表明，掺杂影响GaN单晶硬度的主要原因是缺陷对GaN位错增殖、滑移的阻碍作用和掺杂引起的GaN晶格常数的变化。

Effect of Doping on the Mechanical Properties of GaN Crystals

The study of the mechanical properties of GaN single crystals can help to solve the problem of cracking in the growth, processing and device applications. In this paper, the elastic modulus and hardness of GaN single crystals with different doping types (undoped, Si-doped and Fe-doped) were tested by nanoindentation method to explore the effect of doping on the mechanical properties of GaN single crystals. The test results show that doping has an important effect on the hardness of GaN single crystals. The hardness of Si-doped and Fe-doped GaN samples are higher than that of undoped sample, this conclusion was also proved by the comparison of heavily doped ammonothermal GaN single crystals. Through high-resolution X-ray diffraction analysis and atomic force microscopy characterization, it is found that factors such as crystal crystalline quality and contact area have less influence on the hardness of GaN single crystals. The nanoindentation slip band length and crystal lattice constant of GaN surface were measured. The results show that, the main reasons for doping affecting the hardness of GaN single crystals are the hindering effect of defects on GaN dislocation multiplication and slip, and the change of GaN lattice constant caused by doping.