Recent developments in the high growth rate technique of device-grade microcrystalline silicon thin film

Abstract

A novel approach for deposition of device-quality microcrystalline silicon at a high rate using plasma-enhanced chemical vapour deposition has been developed under high-pressure depletion conditions. This method enables us to obtain materials with good crystallinity up to a high deposition rate of 3.8 nm s−1 at around 300°C. Further improvements in the crystallinity as well as electrical properties have been achieved using a mesh electrode with a hollow-like discharge around the mesh. This hollow mesh method results in a low defect density of 2.6 × 1016 cm−3 and a volume fraction over 70% at a growth rate of 5.8 nm s−1. Another beneficial effect of this method was complete suppression of powder formation even at the high deposition pressure. These methods have been applied to solar cells, and an efficiency of 8.1% has been obtained at 1.2 nm s−1.