AlGaN Heterostructure Optimization for Photodetectors

Abstract

GaN-based photodetectors are of great interest for applications involving detection and imaging in the UV-visible wavelength range. Most of experimental and theoretical work in this area has been focused so far on Schottky diode and p-i-n structures for solar blind applications. However, it seems that bipolar phototransistors with their additional functionality could also be of potential interest. In this work we present the results of phototransistors parameters simulation using the software – Sim Windows. The structure analyzed consisted, counting from the substrate, of n-Al[x]Ga1 – [x]N collector, p-GaN base and n-Al[x]Ga1 – [x]N emitter. The Al mole fraction in the collector and emitter was varied from x = 0.2 to x = 0.3. The collector and emitter thickness was taken as 0.9 hm. The doping level in the emitter and collector was varied from 1017 to 1019 cm – 3. The p-GaN base thickness was taken as 0.3 m, with doping of 1017-1018 cm – 3. The electron and hole lifetimes in the base were taken as 12 ns.