Stoichiometry-Controlled Synthesis and Optoelectronic Performance of 2D InSe

Abstract

Two-dimensional (2D) indium selenide (InSe) is a promising semiconductor for next-generation optoelectronics, but high quality nanoflakes with controllable stoichiometric ratio have not achieved, furthermore and the performance suffers from defective limitation. We report a crystal growth strategy that adopts various stoichiometric ratio of In/Se in melt, two types high crystallinity InSe and InSe0.92 crystals acquired by vertical Bridgman (VB) method and enables precise regulation of defects. The distinct chemical compositions and crystal structures of the derived indium selenide with different stoichiometric ratio will be revealed with the aid of multiscale characterization techniques. The as-obtained crystals demonstrate exceptional composition uniformity, a pure phase structure, and a high crystallinity. The two types crystals of InSe and InSe0.92 crystals exhibit different defect concentration and types. In addition, their optoelectrical devices also be examined to unravel the stoichiometry-dependent electronic properties. Optoelectronic devices based on the produced InSe0.92 nanoflakes demonstrate outstanding electronic transport performance surpassing that of InSe-based devices, including an extremely high photoresponsivity (from 0.132 to 169.731 A/W) at room temperature. However, optoelectronic devices based on InSe nanoflakes demonstrate quickly response speed (from 6.157 to 0.078 s of raise time and 0.167 to 0.04 s of decay time). Overall, this research is expected to propel the stoichiometry-tunable fabrication, the related physical property explorations, and the versatile applications of 2D indium selenide materials in next-generation electronic and optoelectronic devices.