具有图形化Al背面反射镜的GaN基LED芯片

Ga N-Based Light-Emitting Diode Chip with Patterned Al Backside Reflector

图形化反射镜能提高LED芯片的光提取效率.在蓝宝石衬底背面制备三角周期排列的微米尺寸Si O2圆台形结构,再沉积金属Al,构成图形化反射镜.基于Monte Carlo光线追迹方法的三维光学仿真表明,相比平面反射镜,图形化Al反射镜可使芯片光提取效率提升7.5%.实验测试结果表明,输入电流为20m A时,相比平面反射镜,图形化Al反射镜可提升芯片输出光功率8.4%,而芯片的电学性能无恶化.基于有限元方法的二维热力学仿真讨论表明,图形化反射镜有利于芯片获得更低的温度和热应力,且微结构附近的应力集中对芯片性能的影响可忽略.

Patterned reflectors can improve the light-extraction efficiency of light-emitting diode（ LED） chips. In the investigation,a triangular lattice of the micro-scale Si O2-cone array was placed on the backside of a sapphire substrate,and then the metal Al was deposited on the lattice,so that a patterned reflector was built. Three-dimensional simulation results obtained through the Monte Carlo ray tracing method show that,as compared with the plane mirror,the SiO2-cone patterned Al backside reflector can improve the light-extraction efficiency of LED chips by7. 5%. Experimental results indicate that,when the injection current is 20 mA,the LED samples with the patterned reflector achieve a light-output power increase by 8. 4% without the degradation of the electrical performance,in comparison with those with plane mirrors. It is found from the two-dimensional finite-element thermodynamic simulations that the pattern reflector helps to achieve lower chip temperature and smaller chip thermal-stress in comparison with the plane mirror. In addition,the thermal stress concentration in the vicinity of micro-structures has little effect on the performance of LED chips.