激光剥离Al_2O_3/GaN中GaN材料温度场的模拟

Temperature field simulation of GaN material during Al_2O_3/GaN laser lift-off

对激光剥离Al2O3/GaN技术,建立了紫外脉冲激光辐照过程中GaN外延层内热传导理论模型。计算分析了不同能量密度脉冲激光辐照时,GaN外延层内的温度场分布,由此得到激光剥离的阈值条件。采用紫外KrF准分子激光器对Al2O3/GaN样品进行激光剥离实验,样品表面显微镜和端面扫描电镜(SEM)测试照片说明,计算结果与实验现象相符。进一步分析表明,脉冲激光的能量密度和频率是实现激光剥离的关键参数,适当选取这些参数能将GaN材料内的高温区控制在100nm以内,实现高效低损伤激光剥离。

Heat flow model in GaN films irradiated by ultraviolet pulse laser in laser lift-off technique was established. The temperature field of GaN films irradiated by pulse laser with different energy density was calculated. The threshold energy density necessary for laser lif^-off is obtained from the calculation. The AI203/GaN laser lift-off experiment using KrF excimer laser was also carried out. The images of microscope and Scanning Electron Microscope （SEM） from the experiment show the calculation results are consistent with experiments. It is also found that the frequency and energy density of pulse laser are the key parameters for laser lift-off technique. Using the proper parameters, high temperature region in GaN can be confined to 100nm in depth, and laser lift-off with high efficiency, low damage can be realized,