Growth And Properties Of In₂Se₃ Nanostructures

Indium selenide?In₂Se₃?,as a typical type ?-? compound semiconductor,possesses the characteristics of high resistivity and multi-phase.Because of its special electrical and optical properties,it has been widely applied to photodetectors,solar cells,and random phase change memory devices?PRAM?,and so on.Therefore,In₂Se₃ semiconductor material is one of the hotspots in the field of Optoelectronics and storage fields.In this paper,In₂Se₃ nanowires and In₂Se₃ nanosheets were successfully fabricated by chemical vapor deposition?CVD?semiconductor technology on the Si substrates and the fluorophlogopite mica substrates,respectively.The nanostructure samples were characterized and studied by scanning electron microscopy?SEM?,energy dispersive spectroscopy?EDS?,Raman scattering spectroscopy?Raman?,X-ray photoelectron spectroscopy?XPS?,X-ray diffraction?XRD?,photoluminescence spectrum?PL?,and transmission-absorption spectroscopy.The main results are following:1.The In₂Se₃ nanowires were successfully grown on the silicon substrates by Au catalyzed chemical vapor deposition?CVD?process.The lattice structure of the nanowires was determined to be ? phase by Raman spectra.EDS spectra showed that the atomic proportion of the In elements and Se elements in the nanowire samples was close to 2:3.XPS showed the In element existed in the +3 valence and the Se element existed in the-2 valence.PL spectrum showed that the optical band gap of the single?-In₂Se₃ nanowire sample is approximately at 1.72 eV,and there was no luminescence peak caused by impurities or defects in the nanowire samples,which indicates that the nanowires grown by this method were in good quality.The I-V test of nanowires shows that the resistance of the single nanowire is in the order of magnitude of 1013?.The light generation carrier will be produced after the white light irradiation,the resistance is reduced by two orders of magnitude.2.In₂Se₃ nanoplates were successfully prepared by CVD on fluorophlogopite mica substrates without catalyst.The nanoplate sample was determined to be y phase by analyzing Raman and EDS data.The growth mechanism of the nanoplate was considered to be Van Der Waals epitaxy along?001?crystal orientation by the analysis of SEM,AFM and XRD.By post-growth annealing process in Ar atmosphere,it was found that the decreasing In vacancies caused the disappearance of the luminescence peaks induced by the In vacancy defects of the PL spectrum and the percentage of the In atoms increased from EDS data.By Gaussian Fitting,we obtained the dominate luminescence mechanism was originated from near band gap emissions of the free exciton.The optical band gap of the ?-In₂Se₃ nanoplates was about 1.89eV.By studying the transmission-absorption spectrum of the sample,we could determine the band gap of the ?-In₂Se₃ nanoplates to be about 2.07eV.Moreover,we could approximately calculate the optical absorption coefficient of the ?-In₂Se₃ nanoplates to be the order of 105cm-1 magnitude.