使用时域有限差分法(FDTD)研究了蓝宝石衬底上的GaN三角脊的光学特性。分析了不同顶角角度的GaN三角脊的截面光场分布, 结果表明, 三角脊结构可以有效地使光聚集在顶部。分析了不同顶角角度下GaN三角脊的截面电场强度的最大值, 结果表明, 随着顶角角度的增大, 其最大电场强度先逐渐增大后趋于小幅振荡。当其顶角角度较小时, 仅在三角脊尖端处产生一个光场极大值区域, 随着顶角角度的增大, 在脊顶部会产生多个极大值区域。分析了GaN三角脊中量子阱层附近的光场分布, 结果表明, 随着顶角角度的增加, 量子阱层附近的平均电场强度先基本不变后振荡增加, 量子阱层附近的光场由均匀分布逐渐趋于不均匀分布。从研究中发现, 当顶角角度处于40度至60度时, 量子阱与光子耦合作用更强, 这为基于GaN三角脊的高光子密度器件提供了器件设计的理论基础。

The optical properties in GaN triangular ridges on sapphire substrate using finite-difference time-domain (FDTD)has been studied. The light field distribution of the cross section in the GaN triangular ridges with different apex angles was analyzed, showing that the triangular ridge structure could effectively concentrate the light on the top. The maximum electric field intensity of the cross section in GaN triangular ridges at different apex angles was analyzed, showing that as the apex angle increased, the maximum electric field intensity firstly increased and then tended to oscillate slightly. When the apex angle was small, only one light field maxima region was generated at the tip of the triangular ridge, as the apex angle increased, a plurality of maxima regions were generated at the top of the ridge. The light field distribution near the quantum well layer in the GaN triangle ridge was analyzed, showing that as the apex angle increased, the average electric field intensity near the quantum well layer firstly remained unchanged and then increased in oscillation. The light field near the quantum well layer gradually changed from uniform distribution to uneven distribution. It was found from the research that the quantum well and photon coupling were stronger when the apex angle was between 40 and 60 degrees, which provided the theoretical basis of device design for high photon density devices based on GaN triangular ridge.