Oriented Growth of CuInSe<sub>2</sub> Thin Films by Means of Cu<sub>2</sub>Se Interfaces

Abstract

As the optical absorption coefficient in a range of solar spectrum is largest among known semiconductor materials, only 1 μm thick CuInSe 2 can absorb sunlight sufficiently. Furthermore, as the band gap of CuInSe 2 is as narrow as ∼1 eV, it is expected as a promising material for absorption layers in thin film solar cells. In spite of these desirable properties, CuInSe 2 must satisfy some electrical and optical conditions, which depend on structural and crystallographical conditions of films. We have found that Cu 2 Se thin layer tends to have a strong preferred orientation, and CuInSe 2 grown on it can have the strong (112) preferred orientation and the smooth surface, necessary to fabricate high quality heterojunction.