Plasma CVD for Producing Si Quantum Dot Films

Abstract

Si quantum dot films are deposited using a multi-hollow discharge plasma CVD method. For the method, Si nano-crystallites of a small size dispersion and radicals are produced using H2+SiH4 VHF discharges, and then they are co-deposited on to a substrate to form Si quantum dot films, that is, a-Si:H films containing nano-crystallites. The films have a wide optical band gap of 1.8 eV and a large optical absorption coefficient similar to those of a-Si:H films. They also have a low initial defect density below 1 times 1016 cm-3 and show high stability against light soaking. These results suggest that the Si quantum dot films are promising materials for solar cells