Salt-Assisted Growth of Ultrathin GeSe Rectangular Flakes for Phototransistors with Ultrahigh Responsivity

• DOI: 10.1021/acsami.9b06425
• Publication Date: 2019-06-12T09:33:12Z
• Authors: Xiaozong Hu; Pu Huang; Kailang Liu; Bao Jin; Xun Zhang; Xiuwen Zhang; Xing Zhou; Tianyou Zhai
• Keywords: 02 engineering and technology; 0210 nano-technology

Two-dimensional (2D) GeSe is an important IVA-VIA semiconductor for future applications in electronics and optoelectronics because of its high absorption coefficient, mobility, and photoresponsivity. However, the controllable synthesis of 2D GeSe flakes is still a huge problem. Here, high-quality single-crystalline ultrathin 2D GeSe flakes are synthesized by a salt-assisted chemical vapor deposition method. The flakes tend to grow along the [010] crystal orientation presenting a rectangular shape with a thickness down to 5 nm. Then, the electrical and optoelectronic properties have been systematically investigated. A thickness-dependent Schottky barrier is shown in GeSe field-effect transistors. The p-type conductivity of GeSe is mainly caused by the Ge deficiency, which is proven by a variable-temperature experiment and theoretical calculations. In addition, the phototransistors based on as-grown GeSe flakes present an ultrahigh responsivity of 1.8 × 104 A/W and an excellent external quantum efficiency of 4.2 × 106%.