Amorphous and microcrystalline silicon solar cells

Thin-film silicon exists in different phases, ranging from amorphous via microcrystalline to single crystalline. In contrast to the periodic lattice that characterises the crystalline form, there is only very short-range order in amorphous silicon (a-Si:H). The first amorphous silicon layers were deposited in an rf-driven glow discharge using silane. This deposition technique is now usually called plasma-enhanced chemical vapour deposition (PECVD). The hot-wire CVD (HWCVD) technique is based on the decomposition of silicon-containing gases at a catalytic hot surface. Today many groups study HWCVD thin-film silicon and its alloys for various applications such as solar cells, passivation layers, and thin-film transistors. This chapter discusses the basic operation of a basic thin-film silicon solar cell and then presents the thin-film structure and technology. It also talks about the status of the technology of single-junction cells in the laboratory.