Numerical modeling and design of single photon counter 4H-SiC avalanche photodiodes

We report device performance investigation of 4H-SiC avalanche photodiodes (APDs) with or without absorbing AlGaN cap layers, as 4H-SiCspsila potential use in single photon counter APDs have drawn interest. Wide bandgap 4H-SiC photodiodes have low dark current levels at high temperatures and under intense radiation compared to silicon, and the 4H-SiC APDs are ldquosolar blindrdquo - transparent to the sunpsilas visible spectrum. Additionally, they offer avalanche multiplications approaching a million, making single photon count possible. However, design and optimization of single photon counter APDs require a thorough understanding of impact ionization and optical absorption at the material level, and steady-state and transient APD operation at the device level. Here we address both of these levels.