(Invited) Enhancing the Deep Ultraviolet Performance of 4H-SiC Based Photodiodes

Abstract

In this paper we report on two new approaches for increasing the the deep ultraviolet response (l < 260 nm) of 4H-SiC photodiodes by employing p-n- SiC- metal or p-n- SiC – n- AlxGa1-xN structures. The p-n- SiC- metal diodes, employing a transparent window metal, have a nearly flat response between 200-270 nm with peak external quantum efficiency (EQE) of 45%. A peak QE of 76% is observed for the p-n- SiC – n- AlxGa1-xN diodes at 242 nm. The significant enhancement in short wavelength response observed in both diodes is attributed to preferential absorption of deep ultraviolet photons within the depletion region of these structures as compared to that in the top doped layer of a p-i-n SiC photodiode, and the more efficient collection of photo-generated carriers through drift despite the presence of surface/interface states.