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通过热力学理论对物理气相传输(PVT)法AlN晶体生长过饱和度进行分析,分别从软件模拟和晶体生长实验对衬底表面的温度分布进行调控,进而控制衬底表面AlN晶体生长的驱动力。理论上,采用Comsol模拟软件对坩埚结构的温度分布进行模拟仿真,模拟结果表明:复合型衬底可以显著改变衬底表面的温度分布,达到改变衬底表面AlN气氛的过饱和度的目的;实验上,采用PVT法AlN晶体的生长实验验证了软件模拟结果。采用复合型衬底生长AlN晶体时,通过对衬底表面的温度分布调控可有效控制晶体生长驱动力,进而实现形核位置和形核数量的控制。经过6~8 h AlN晶体生长后,可获得尺寸约为12 mm、厚度约为3 mm的AlN单晶。喇曼光谱和XRD双晶摇摆曲线测试结果表明晶体质量良好。
The thermodynamic theory was used to analyze the supersaturation of AlN crystal grown by physical vapor deposition (PVT) method. The temperature distribution on the surface of the AlN crystal was controlled by software simulation and crystal growth experiment, respectively, to control the driving force of AlN crystal growth on the substrate surface. Theoretically, the temperature distribution of the crucible structure is simulated by Comsol simulation software. The simulation results show that the composite substrate can significantly change the temperature distribution on the substrate surface to achieve the purpose of changing the supersaturation of the AlN atmosphere on the substrate surface. The experiment The simulation results of AlN crystal grown by PVT method are validated. When the AlN crystal is grown on a composite substrate, the driving force for crystal growth can be effectively controlled by adjusting the temperature distribution on the substrate surface, and the nucleation position and the nucleation quantity are controlled. After 6 ~ 8 h AlN crystal growth, the AlN single crystal with the size of about 12 mm and the thickness of about 3 mm can be obtained. Raman spectroscopy and XRD twin crystal rocking curve test results show that the crystal quality is good.