Current status and future prospects of semiconducting alkaline-earth-metal silicides

Abstract

β-FeSi₂ has been extensively studied as a Si-based infrared-light emitter over the past ten years. On the other hand, alkaline-earth-metal silicides such as Mg₂Si and BaSi₂ have attracted less attention. However, they have very interesting features as follows. The band gap of Mg₂Si can be controlled from 0.7 to 0 eV by replacing the Si atoms with other group 14 elements such as Ge, Sn and Pb. BaSi₂ has a very large optical absorption coefficient, comparable to that of chalcopyrite semiconductors. In addition, it was recently reported that the band gap of BaSi₂ increases from 1.3 eV by the replacement of some of the Ba atoms with Sr. In this article, recent studies on BaSi₂ such as epitaxial growth techniques, electrical and optical properties and band structure calculations are described.