Fabrication of high-quality boron-doped microcrystalline silicon thin films on several types of substrates

Abstract

Boron-doped (p-type) μc-Si:H thin film window layers are widely used in silicon thin film solar cell fabrication due to their low optical absorption and high doping efficiency compared with their amorphous counterparts. In this paper, the layer-by-layer method is investigated to fabricate high-quality thin p layers (< 30 nm). To investigate the influence of the type of substrate, p layers are deposited onto planar glass and textured glass (bare or coated with ZnO:Al thin film). The crystalline volume fraction (crystallinity) and conductivity of the deposited p layers are measured to characterise the films' properties. We find that by increasing the number of hydrogen plasma treatment steps and their duration, the films' crystallinity and electrical properties improve strongly. We also find that the substrate surface roughness strongly influences the film properties. This may be due to the different nucleation conditions resulting from the various substrate topographies. © 2012 Published by Elsevier Ltd.