Study On The Optical Characters Of P-Type Gan Epitaxial Films With Fifferent Annealing Temperature

The third generation of wide bandgap semiconductor materials, especially the III-Nitride semiconductors and their alloy represented by gallium nitride (GaN) had caught a lot of attention and amount of research had been done on them, since they have many outstanding characters such as wide bandgap, a variable wide wavelength range, a good elevated temperature properties and so on. So far, GaN and GaN based semiconductor material have been widely applied in manufacturing LED, semiconductor laser and photoelectric detector. Because GaN material has a high n-type background carrier concentration, High-quality p-type GaN access has been a difficult problem for a long time. Now, Dealing with Mg-doped GaN by rapidly high temperature annealing, High-quality p-type GaN can be obtained. Researching on the optical constant of GaN is necessary for the GaN based ultraviolet photodetector. Since most of the researches which had been done on the optical constant of GaN were about the wavelength range below the bandgap, it is important to find out a reasonable mathematical formula to describe the optical constant in the full wavelength range. The annealing temperature has an effect on the photoluminescence and the quality of semiconductor material. Since the optimized growing parameters are important for growing a high quality GaN epitaxial film, it is wealthy to make a system research on the optimized growing parameters.This work firstly introduces the overview of GaN, the base characters of GaN, the method to access p-type GaN, the difficulties of growing high quality p-type GaN, the GaN epitaxial film growing technique and the sample related in this research. Then ellipsometry, Raman scattering and photoluminescence were performed to study the optical constant, in-plane stress and photoluminescence of the p-type GaN samples with different annealing temperature.The main research work of this paper:(1) By theoretically fitting the ellipsometry data of p-type GaN, it is found that the Tauch-Lorentz model can be utilized to describe the optical constant of p-type GaN in the full wavelength range. Studying how the different annealing temperatures make an effect on the optical constant and the optical anisotropy of p-type GaN.(2) Utilizing the Raman spatial correlation model to analyze the in-plane stress in p-type GaN epitaxial films.(3) Photoluminescence was performed to study how the different annealing temperatures make an effect on the photoluminescence and the best annealing temperature was obtained. The reasons that induced the photoluminescence peak were presented. Varying temperature photoluminescence was also performed to study relationship between the temperature and the value of bandgap.