GaN设计方法方案.docx

GaN设计方案 Introduction GaN is a wide band gap direct bandgap semiconductor material with high saturation electron drift velocity, low dielectric constant, good thermal conductivity and high temperature resistance, anti-acid corrosion and excellent chemical stability, and therefore very suitable for the production of anti-radiation, high-frequency, high-power and high-density integrated electronics [1]. Due to the characteristic that its band gap characteristics can be regulated, GaN can be used to produce blue, green and UV light emitting device and a light detecting device [2]. The crystal quality of the material has a powerful influence on the performance and life of the device [3]. GaN-based semiconductor materials contain a variety of defects and among them the threading dislocations play a dominant role. The conventional method to reduce dislocation density in semiconductor usually uses the constant composition of buffer layers. Such method has made good progress in SiGe/Si or InGaAs/GaAs systems [4]. The dislocations in these systems can meet each other and react and constantly reduce the dislocation density as growth proceeds. But the situation is different in the GaN film which has the hexagonal wurtzite structure. From former research, we know that majority of the dislocations in the GaN films are edge dislocations which have Burgers vector b = < 1 1 0 >, some screw dislocations which have Burgers vector b = < 1 1 0 1 > and some mixed dislocations which have Burgers vector b =1/3 < 1 1 3 > [5]. The directions of the majority of these dislocations are found to be normal to the substrate interface and also parallel to the [0 0 0 1] direction [6]. Further study shows that for the reason that mixed dislocations tend to the film normal at about 12°, buffer layers have limited effect on lowering the dislocation densities in GaN [6]. In this work, we show how to use X-ray diffraction (XRD) technology to measure and calculate the densities for the edge dislocation