PROPERTIES OF A NEW A-SI-H-LIKE MATERIAL - HYDROGENATED POLYMORPHOUS SILICON

A new a-Si:H-like material has been obtained in a radio frequency-powe red plasma-enhanced chemical vapor deposition system (RF-PECVD). This material prepared with dilution of silane into He or H-2, under high t otal pressure (approximate to 132 Pa) and high RF power exhibits enhan ced electronic transport properties. The room temperature electronic m obility-lifetime product is increased by a factor up to 200 compared t o hydrogenated amorphous silicon (a-Si:H) prepared under standard depo sition conditions (lower pressure, lower RF power). The density of sta tes measured by modulated photocurrent and the deep defect density mea sured by the constant photocurrent method are both less than that of s tandard a-Si:H. These transport properties are linked to the structure of this new material deposited under conditions close to those for po wder formation. This structure seems to result in a decrease of the de ep defect density and capture cross sections. (C) 1998 Elsevier Scienc e B.V. All rights reserved.