The Influence of Structure Parameter on GaN/AlN Periodically Stacked Structure Avalanche Photodiode

Recently, we have verified an inter-valley scattering free avalanche photodiode (APD) by using GaN/AlN periodically stacked structure (PSS). High linear-mode gain and extremely low excess noise have been achieved in a prototype GaN (10 nm)/ AlN (10 nm) PSS APD. In this letter, device optimization is investigated theoretically. Gains and excess noises are simulated in PSS APDs with different periodical structures and periods. It is found that the gain and excess noise can be optimized alternatively by a proper design of periodical thickness and AlN layer occupancy. Furthermore, although the highest gain that a PSS APD can achieve holds a positive relationship with periods, decreasing periods is preferred to reduce excess noise.