Study On Energy Deposition And Induction Effect Of GaN - Based LED Electron Beam Irradiation

With the advantages of energy conservation, high efficiency, long use cycle and so on, LED is replacing the traditional lighting source. However, there are radiation in outer space and human survival environment, which will produce radiation damage to LED, thus changing the lighting effect. Therefore, the study of irradiation damage of LED has become the focus of improving the performance of LED.Electron beam irradiation can change the life of non-equilibrium carriers in PN junction epitaxial wafer, thus leads to degradation of LED devices. This paper mainly discusses the energy deposition and the induced effects in the process of the electron beam irradiation on GaN based LED.1. Simulation of energy deposition in GaN with different incident electron energy. First of all, the analytical method is used to simulate the energy damage of the electron beam in the GaN based LED’s multilayer structure. It can be concluded that with the increase of the incident energy, the main energy deposition distribution is transferred from each layer to the interface, and the interface of the energy transmission line is obvious. Then the Monte Carlo method is used to simulate the energy deposition distribution in GaN irradiated by different incident energy. After comparison, it was found that the effect of irradiation on the surface layer material is greater, and the higher the energy, the stronger the electron beam penetration is2. The first-principles is used to separately calculate the performance changes of the irradiated GaN materials casued by the defects of VN, VGa, GaN, MgGa, MgGa-ON, MgGa-H, MgGa-VN, VGa-ON, and the performance changes of the multi quantum well structures doped with different In components. The changes of optical properties is analyzed emphatically, and it is obtained that the most intense absorption peaks are generated from the Ga3d or N2p states to the low energy level. And VN, GaN are making the strongest absorption peak red shift, the peak position was not changed when doped by MgGa-VN, while other defects leading to the main peak blue shift. And the main peak intensity is increased under the Mgca doping, while it is almost unchanged under the MgGa-H doping, and other defects decrease the peak intensity. With the increase of In concentration, the P-state electronic lead to the band gap decreases, while also makes InGaN red shift.3. The PL spectra of GaN based LED samples obtained under different irradiation conditions were tested to analyze the changes of their luminescence properties. Then, with the theoretical calculation results, the main defects in the samples after irradiation were analyzed. When the irradiation energy is 1.5MeV, the defects of N position and Mg substitution are mainly appeared in the samples under the 5kGy dose irradiation, and the O complex defects are mainly appeared under the lOkGy dose irradiation. Analyses of the room temperature PL spectra of InGaN quantum wells in samples show that 3MeV irradiation mainly produces N-bit defects that causes PL spectra to red shift, and 4.5MeV irradiation mainly produces Ga-bit defects that causes PL spectra to blue shift. While before radiation, the variable temperature PL spectra change is determined by the carrier relaxation time. After 4.5MeV irradiation, the variable temperature PL spectra change is caused by In component diffusion results.