Optimization of GD a-Si: H Film Property for Photovoltaic Device by Means of the Cross Field Plasma Deposition Technique

Abstract

A systematic study has been made on the relationship between plasma deposition condition and electronic properties of a-Si: H film by employing the cross field plasma deposition technique. Three important processes of deposition mechanism, i.e. i) plasma decomposition, ii) transport of ionized and neutral radicals and iii) compiling of decomposed species were separately identified by this technique. Remarkable improvements in the film quality have been obtained, that is, AM 1 photoconductivity of more than 5×10-4 mho/cm with the optical gap of 1.73 eV in the undoped film deposited at the optimum bias voltage of -50 V and the substrate temperature of 350°C. Another noticeable result is an enhancement of boron doping efficiency realized by applying an appropriate positive bias voltage of + 100 V. These improved films have been utilized to construct p-i-n heteroface solar cells.