Electrical and Optical Modeling of 4H-SiC Avalanche Photodiodes

Optimal physical models and material parameters for 4H-SiC avalanche photodiodes (APDs) were studied using a two-dimensional device simulation tool. In the models, we took account of temperature-dependent impact ionization and absorption coefficient as a function of wavelength. The absorption coefficient spectra derived in this work exhibited a rapid increase below ∼300 nm, which can be qualitatively incorporated into indirect and direct band transition models. The simulated characteristics were in good agreement with the measured characteristics.