PHOTODETECTION ENHANCEMENT IN 2-TERMINAL AMORPHOUS SILICON-BASED DEVICES - AN EXPERIMENTAL AND COMPUTER-SIMULATION STUDY

Although amorphous silicon (a-Si:H) is very photosensitive and can be doped n and p type, it does not give effective phototransistors becaus e of the extremely poor diffusion lengths. Hence enhanced photodetecti on in two-terminal a-Si:H devices is of considerable interest. Using t he Analysis of Microelectronic and Photonic Structures (AMPS) computer model, we explore enhanced photodetection possibilities in two-termin al a-Si:H structures and show situations where it can occur. These sit uations, which we then experimentally verify, are of two types: one ca n yield quantum efficiencies greater than unity and the other can yiel d gains of 10(3). Both of these enhanced photodetection situations occ ur because of what we term photogating.