Optimisation of Microcrystaline Silicon Deposited by Expanding Thermal Plasma Chemical Vapor Deposition for Solar-Cell Application

The causes for the porosity of the microcrystalline material deposited by the expanding thermal plasma (ETP) chemical vapor deposition (CVD) technique have been investigated through IR-absorption measurements. The role of impinging ions on the structure of the material is discussed in relation to the hydrogen bounding configuration (microcrystalline factor). The ion energy is controlled through external RF biasing. Correlation between biasing and reduction of porosity is presented. The influence of high deposition pressure is as well studied, related with changes in a-Si structure.