Type-II InSe/GaP van der Waals heterostructure: Enhanced carrier mobility and a continuously field-tunable band gap

Two-dimensional van der Waals heterostructures have been regarded as an ideal platform for sub-10 nm nanoelectronic devices, owing to their atomic thinness and tunable electronic properties. This work, employing first-principles calculations, focuses on analyzing the structural, stability, electronic, transport, and field-modulated properties of an InSe/GaP heterostructure. Among five stacking configurations, the most dynamically stable ground state was identified through evaluation of binding energy and phonon dispersion spectra, with the ordering confirmed against three independent dispersion corrections. Using the more accurate hybrid functional, a semiconducting channel was revealed with an indirect energy bandgap of 1.12 eV, type-II band alignment and a high peak absorption coefficient. A potential step of 4.23 eV was found across the interface, which together with the type-II alignment suppresses carrier recombination. Transport calculations reveal an electron mobility exceeding that of either constituent monolayer, together with a hole mobility roughly two orders of magnitude above that of isolated InSe. An out-of-plane electric field tunes the gap continuously and linearly while preserving the type-II alignment. These results establish InSe/GaP as a promising candidate for ultrafast logic switches and optoelectronic integrated circuits.