Lattice vibration characteristics in layered InSe films and the electronic behavior of field-effect transistors

Understanding how temperature affects the structural and electronic properties for two-dimensional (2D) semiconductors could promote the application and development of nanoelectronic devices. Here, the temperature dependence of lattice structure for indium selenide (InSe) nanosheets and the corresponding electronic properties of 3 nm indium-deposited InSe field-effect transistors (FETs) are systematically demonstrated. Analyses of Raman spectra suggest that the difference of phonon frequency (Δω) for the A mode is found to be 3.14 cm-1, which is larger than that of the E mode due to the stronger electron-phonon coupling for the A mode. The device performance based on indium-deposited InSe is systematically explained using Kelvin probe force microscopy (KPFM) and the predicted energy band structure. Furthermore, FETs based on temperature and variable thickness InSe flakes are designed as applicable devices. Our findings are of fundamental importance to explain the underlying physics in intrinsic InSe transistors and improve further applications.