Cryogenic Hole Transport in 2D Indium Selenide

Atomically thin two-dimensional (2D) indium selenide (InSe) holds great promise for next-generation semiconductors for beyond-silicon electronics, but its practical implementation and fundamental transport studies have been largely limited to n-type operations. In this work, we demonstrate p-type InSe field-effect transistors utilizing high-work-function Pt bottom contacts and hexagonal boron nitride encapsulation, enabling metallic hole injection down to 1.5 K and an impurity-limited mobility exceeding 3,000 cm2/(V s). Temperature (T)-dependent transport measurements reveal a metal-insulator crossover at low carrier densities, presumably accompanied by strong carrier interactions associated with the large effective hole mass at cryogenic T, whereas acoustic phonon scattering dominates at higher T. The mobility is further suppressed by intrinsic and remote interfacial optical phonons, consistent with enhanced phonon-assisted trapping-detrapping, as evidenced by low-frequency noise spectroscopy. Our study elucidates the hole transport characteristics of InSe, providing a platform for exploring strongly interacting systems and broadening the range of viable p-type semiconductors for cryogenic electronics.