| Among the two-dimensional group IV-VI material M(M=Ge,n;=,e),two dimensional germanium selenide(Ge e)is a promising semiconductor material with a direct band gap.As a new two-dimensional material,it has a wide spectrum absorption range and has potential applications in optics,electronics and other fields.At present,the research on the adsorption gas on Ge e surface only stays in the theoretical research stage.In this thesis,two-dimensional Ge e nanosheets were successfully prepared by mechanical exfoliation and high-temperature heating methods,and the dual electrode devices were fabricated by micro nano fabrication technology.On this basis,the conductivity of two-dimensional Ge e nanosheets for oxygen and butane gas adsorption was explored,which established an experimental foundation for the development of two-dimensional Ge e gas detector.The main results are as following:(1)By optimizing the experimental process of the preparation of Ge e nanosheets under high temperature,combined with the mechanical peeling method,the Ge e nanosheets with several atomic layer thickness were successfully prepared.The samples of Ge e were characterized by scanning electron microscope(EM),Raman spectrum microscope,atomic force microscope(AFM)and photoluminescence(PL)spectrometer.The experimental results show that the two-dimensional Ge e sample has a uniform surface,and its thickness is about 5nm.It has photoluminescence spectra from visible light to near-infrared region.(2)The bipolar Ge e electrode device was fabricated by a series of micro and nano processing technologies,including mechanical exfoliation,uniform photoresist,laser direct writing,evaporation coating,stripping residual glue and so on.It is found that when Ge e nanosheets has the adsorption of oxygen,the conductivity is increased with the increasing of gas concentration.This is due to the fact that when the oxidizing oxygen is adsorbed on the surface of p-type semiconductor Ge e,electrons are transfered from the surface of Ge e nanosheets to the gas molecules,which leads to the increasing of hole concentration in Ge e surface and thus its conductivity is increased.When butane gas is adsorption on the surface of Ge e nanosheets,it is found that the conductivity is decreased along with the increasing of gas concentration.The reason is that when the reductive butane gas is adsorbed on the surface of Ge e,the gas molecules are easy to lose electrons,and these electrons istransfered to the surface of Ge e,neutralizing the holes to form electron hole pairs,which leads to the decreasing of carrier holes and leading to the decreasing of electrical conductivity. |
