Research Of Preparation Technology Of GaN-LED Roughening Surface Structure

In recent years, the development of GaN-LEDs is rapid, but its low external quantum efficiency seriously restricts its wide application in semiconductor lighting area. How to increases its external quantum efficiency is discussed in this paper. Through the surface coarsening of GaN-LED, the lights that meet the laws of refraction-such light will change their direction and will not be refracted and through interface when the lights is in another surface or reflected back to the original surface, which improve the efficiency of the lights.LED, as a kind of light source, has an important index, photoelectric conversion efficiency. It is the product of LED quantum efficiencies and extraction efficiency. Quantum efficiency is itself within the lightning conversion efficiency, and it is related to its internal characteristics, such as material band, structure, defect, impurity and base composition and other relevant. While the extraction of efficiency refers to the LED internally generated photons, which can be measured after absorption, reflection and refracted in external components and mainly related to components of material itself with the absorption, the components of the geometric structure, components, the differential of packaging materials refractive index , scattering properties of the components structure, etc. The product of these two kinds of efficiency for the entire components, is the luminous efficiency (outside quantum efficiency).Normally, the surface structure shape and research include two aspects: One is the photonic crystal, the other is surface coarsening. Considering these shapes are 3-dimensional, and the study of the light performance of 3d graphics is difficult. So we simplified them into 2d graphics, namely the study of the biggest shaft cut surface of 3d graphics. In this project, the cylinder surface structure, in which the biggest shaft cut is rectangular, is studied. The theoretical model of rectangular is modeled and optimized . Via making the cylinder photonic crystal, the coarsening of surface is obtained in the experiment, and the theoretical is proved.In this thesis, according to refraction-such laws and simple geometric relations, study has been carried out on how to establish mathematical physics model for the structure of cylinder surface, with the simplified model of rectangular. It is used the light evaluation factor of the model to measure the out-lighting of the device. The out-lighting of the devices is assessed by calculating the light evaluation factor via the model. The size of the model has been optimized twice. Via the simulation optimization, the light evaluation factor is larger and the out-lighting of the device is better as well.It is also introduced how to use surface roughness to enhance light-emitting efficiency of GaN-LED on ITO layer and SiO₂ layer. With the wet etching on ITO layer and SiO₂ layer, the coarsening surface is achieved which improves the light-emitting efficiency of GaN-LED. In addition, LED-microlens on the coarsening surface of SiO₂ layer was made, which increases the light-emitting efficiency of GaN- LED further. There are several experiment schemes about the surface structure. Then, the light power of these devices was measured, and the experiment results showed that the light-emitting efficiency of the devices, which were treated by surface-roughening are enhanced mostly, is near upon 15%.