Quantum confinement and photoresponsivity of β-In2Se3 nanosheets grown by physical vapour transport

We demonstrate that beta-In2Se3 layers with thickness ranging from 2.8 to 100 nm can be grown on SiO2/Si, mica and graphite using a physical vapour transport method. The beta-In2Se3 layers are chemically stable at room temperature and exhibit a blue-shift of the photoluminescence emission when the layer thickness is reduced, due to strong quantum confinement of carriers by the physical boundaries of the material. The layers are characterised using Raman spectroscopy and x-ray diffraction from which we confirm lattice constants c = 28.31 +/- 0.05 angstrom and a = 3.99 +/- 0.02 angstrom. In addition, these layers show high photoresponsivity of up to similar to 2 x 10(3) A W-1 at lambda = 633 nm, with rise and decay times of tau(r) = 0.6 ms and tau(d) = 2.5 ms, respectively, confirming the potential of the as-grown layers for high sensitivity photodetectors.