Nanocrystalline silicon film grown by LEPECVD for photovoltaic applications

Abstract

This work deals with the characterization of nanocrystalline (nc) silicon films, grown using the plasma enhanced chemical vapour deposition (PECVD) process based on a low-voltage–high-current arc discharge plasma named LEPECVD (low-energy PECVD). The structural, electrical and chemical properties of the LEPECVD grown films have been studied as a function of the deposition parameters (substrate temperature, growth rate, silane dilution). The results show that the films consist of elongated nanocrystals along the 〈1 1 1〉direction, embedded in an amorphous matrix. The crystallite size along the 〈1 1 1〉 direction is in the range of 9-20 nm. The volume fraction of crystallinity ( χ c ) varies between 51% and 78%, depending on preparation conditions. Conductivity values of the order of 10 −6 Ω −1 cm −1 for the layers were measured, making the material suitable for the p–i–n junction application.