Enhancement Of Extraction Efficiency Of GaN-based LED Via Surface Roughening

In this paper, we put enhancing light-emitting efficiency of GaN-based LED as a incisive point and mainly introduces the way of roughening upper surface of LED. Theoretically calculates the optimal size of the triangular etching pit. Firstly we analyze the specialized lighting-emitting point in a period through the theoretic analyses as well as drawing the structure pictures. And then we use twice cycle optimizing means. At last by the Matlab we draw the fitting curve and in this way the final optimizing sizes of the triangular etching pit .Furthermore, a better shape and sizes is anticipated through proper shape changing. The research result points out owing to the total internal reflection the angle of different point on the chip are confined so that the sizes and the structures of the surface of chip have a significant affect on the light-emitting efficiency.The expected surface morphology is achieved by using molten KOH to etch green LED epitaxial wafer. Then the LED epitaxial wafer is made into devices by conventional process. In the process of analysis, SEM and AFM is used to observe external surface, at last, three-dimensional shape of etch pits were evaluated and observed respectively. Then the LED epitaxial wafer is made into devices by conventionnal process. The light power is measured. The experiment results shows that the external quantum efficiency of the device which is treated by surface-roughening is enhanced by 25.7%.