Back-gated metal-semiconductor-metal photodetector

In this paper we outline work we have recently completed on the novel high speed photodetector which has come to be known as the 'back-gated metal-semiconductor-metal' photodetector or BG-MSM for short. This device was first realized by E. Greger et. al. and us. Recent theoretical work by Hurd et. al. provided a sound basis by which to test the device against a model. The work presented here clearly indicates that the main conclusion of Hurd et. al. is sound. That conclusion was that the main response speed gain obtained by the back-gating is obtained by simply earthing the back contact. As well as this confirmation we have found strong dependence of the peak height of the response on the back gating voltage and a very strong position dependence of the excitation spot on the response particularly at low applied fields. We conclude that the back gating is an advantage over the conventional metal-semiconductor- metal photodetector and needs to be studied more extensively both theoretically and experimentally using devices capable of operation at above 100 GHz. ©2003 Copyright SPIE - The International Society for Optical Engineering.