Characteristics of Rhombohedral (3R) Structure of a-In2Se3 Nanosheets by Mechanical Exfoliation

The mechanically exfoliated ultrathin 3R a-In2Se3 nanosheets were transferred onto a SiO2/Si substrate. Using atomic force microscopy, it was confirmed that the transferred a-In2Se3 transferred had a thickness of 15-120 nm. The thickness dependence of Raman peaks of E-2, A(1)(1), E-4, and A(1)(2) was observed from the Raman spectra. Moreover, the measured photoluminescence peak values in the range of 869-895 nm indicate a blue shift as the thickness decreases. The field-effect transistor based on a-In2Se3 exhibited an n-type semiconductor behavior. From the transfer curve at gate voltage of 10 V, the derived values of the mobility and ON/OFF ratio are 24.26 cm(2) V- 1 s(- 1) and 1.84, respectively. In addition, it was confirmed that the 3R a-In2Se3 layers had a high photoresponsivity of up to approximately 34,500 A/W under illumination ( ? = 750 nm).