Layer-dependent switching and photodetection in two-dimensional InSe transistors

The two-dimensional layered material-based multifunctional transistors are expected to be core devices in the post-Moore era. However, the relationship between layer thickness and device performance remains unclear. Here, we design the layer $\mathrm{In}\mathrm{Se}$ transistors integrating switching and photodetection functions, exhibiting the fast-switching time and high responsivity when choosing the layer numbers of 2 and 3. Additionally, the maximum photoresponsivity and external quantum efficiency reach up to 0.29 A/W and 136.4% at the wavelength of 310 nm, respectively. The layer-number changing also induces 2 orders of magnitude improvement in and delay time. The dependence between layer number and device performance can provide a basis for designing multifunctional devices.