Optical switching in metal tunnel-insulator n-p + silicon devices

Abstract

This paper considers the mechanism of optical switching and the possible utilisation of the metal tunnel-insulator n-p+ silicon device in optical communication systems. The pertinent design approaches are described. Under optical excitation, photo holes and electrons generated in the surface depletion region, or within diffusion range, will eventually be separated by the electric field and produce an increment in the forward current. Those hole-electron pairs generated in the junction region, or within diffusion range, produce a photovoltaic increase in the p+-n junction bias. Switching is induced optically, as it is electrically, by the build up of holes at the insulator-semiconductor interface. This paper employs the 1-dimensional diffusion equation to derive the light generated minority Carrier distributions and diffusion currents in the neutral n and p+ regions, together with the currents in the surface and p+-n junction depletion regions. The calculated values of both the drift and diffusion currents compare favourably with those observed experimentally.