Silicon Thin Films:Functional Materials for Energy, Healthcare, and IT Applications

The authors review selected topics in the development of hydrogenated amorphous silicon (a‐Si:H), from its emergence some 50 years ago to its present status as a mature thin‐film semiconductor, with market successes including flat‐panel displays, solar modules, and x‐ray scanners. By altering process gas mixtures and deposition conditions, films with a range of atomic, structural, and amorphous/crystalline phase compositions may be deposited, offering tunable bandgap, refractive index, and light‐scattering properties. Films thus “functionalized” have greatly increased scope and utility. Three emerging applications are reported, and more extensive sections on two topics of current importance are presented: 1) Multi‐junction thin film silicon solar cells for water splitting applications; and 2) thin‐film silicon solar cells on flexible substrates.