High Electrical Mobility in Indium Selenide Grown by Molecular Beam Epitaxy (MBE) for High Performance Electronic Devices

Numerous optoelectronic/electronic applications rely on high-mobility semiconductors to transport charge carriers efficiently and minimize power dissipation. Indium selenide (In_xSe_y), with its excellent electronic properties, emerged as a promising candidate for next-generation electronic devices. However, achieving and optimizing high electron mobility in In_xSe_y films remains challenging since its polymorphic nature. Molecular Beam Epitaxy (MBE) provides a controlled growth environment for synthesizing high quality semiconductors with precise atomic layer control. In this study, we explore the impact of MBE growth parameters, specifically the growth temperature and Se/In flux ratio, on the structural and morphological characteristics of In_xSe_y on Si (001) substrate. Morphological, structural, and electrical characterization techniques were performed to elucidate the impact of the growth conditions on the crystal structure and the electrical mobility of the grown films. The results indicate that both growth temperature and Se/In flux ratio have significant influence on In_xSe_y properties. A phase map was constructed within growth conditions. The formation of single phase (γ-InSe or γ-In₂Se₃) and mixed phases (γ-InSe and γ-In₂Se₃), occurs in a small and large growth window, respectively. All films exhibited n-type behavior with the highest Hall mobility exceeding 2000 cm²/Vs achieved for single phase γ-In₂Se₃. The sensitivity of the electrical and morphological properties of In_xSe_y to the growth conditions implies the necessity for precise adjustments of the growth conditions to selectively synthesize single phase γ-InSe or γ-In₂Se₃. Our work paves the way for developing wafer-scale indium selenide as a potential candidate material for high-performance optoelectronic/electronic devices.