Investigation on the optical properties of group-III nitride materials based on fully-connected neural network

Abstract In order to accurately simulate the optical properties of nitride optoelectronic devices, such as the reflection spectrum of distributed Bragg reflectors (DRBs), the optical constant is generally considered an important parameter. In this work, the fully-connected neural network is adopted to predict the real and imaginary parts of ordinary dielectric function (DF) of III-nitrides across the full composition range and wide spectral range. The input parameters include Al-component, Ga-component, In-component, and photon energy. The predicted dielectric constant is basically consistent with the results calculated by the analytical model reported in the literature. Then, the band gaps of 6 eV, 3.4 eV and 0.73 eV for AlN, GaN, and InN were determined by using the Tauc formula. The fitted bowing parameters are 0.94 eV, 4.3 eV, and 1.6 eV for AlGaN, InAlN, and InGaN alloys, respectively. Finally, using the predicted dielectric constant, the calculated reflection spectrum of the DBR structures is in agreement with the experimental results in the literature.