High Mobility γ-Phase Indium Selenide on Si(100) Grown by Molecular Beam Epitaxy

III-VI compounds, such as In x Se y materials, offer an unprecedented potential for electronic devices at the atomic level. Despite their superior electronic properties, most research focused on measuring transport locally within mechanically exfoliated flakes at microscale and sometimes transferred on atomically flat surfaces. However, from a technological perspective, the integration of these materials in electronic devices requires wafer-scale, uniformly grown films, preferably integrated with the dominant semiconductor, silicon. Indium selenide films have recently shown promising electronic performance. Unfortunately, the epitaxial growth of single-phase indium selenide poses challenges due to its polymorphic nature and different stoichiometries, such as alpha-In2Se3, epsilon-for InSe, and beta, gamma for both InSe and In2Se3. Here, we report the growth of single phase gamma-In2Se3 on Si (100), with a Hall mobility exceeding 2000 cm2/(V s) at room temperature. Our study explores the growth parameter space in the Molecular Beam Epitaxy (MBE), specifically the Se/In flux ratio and the growth temperature. It correlates them with the structural, morphological, and electrical characteristics of In x Se y films. A phase map was constructed within the specified growth temperature and Se/In flux ranges. gamma-In2Se3 single phase formation occurs only in a small temperature and Se/In Flux ratio window. In contrast, the formation of a mixture of gamma-InSe and gamma-In2Se3 phases is obtained in a large growth condition window. The sensitivity of indium selenide's electrical and morphological properties to growth conditions implies the necessity for precise adjustments of the Se/In flux ratio alongside the growth temperature to selectively grow large-area single-phase gamma-In2Se3 suitable for advanced electronic devices such as field effect transistors and photodetectors.