| As an IV-VI group semiconductor,GeSe has excellent optoelectronic properties.Two-dimensional GeSe has a direct band gap with a gap value in the range of 1.0–1.2 e V,which is close to the band gap of Si,so single-layer GeSe can be used in the optoelectronic field.Single-layer GeSe has very strong visible light absorption,and only the effects of layer number changes and strain on the photoelectric properties of GeSe have been studied,but the regulation of the photoelectric properties of GeSe by defects,doping,coexistence of doping defects,and coexistence of doping and strain is still less studied.In this paper,Materials Studio software is used to construct a single unit cell stereoscopic structure and two-dimensional single-layer planar structure of GeSe bulk materials.The first principle method based on density generalization theory is applied to the CASTEP module to study the photoelectric properties of GeSe and its regulation mechanism.A two-dimensional planar structure model of GeSe coexisting with adsorption,doping or doping was constructed to study the regulation behavior and regulation mechanism of doping and adsorption on the band gap and photoelectric properties of GeSe monolayers.Firstly,the effect of Al,O,B adsorption on the photoelectric properties of two-dimensional GeSe materials was investigated.The calculation results show that the electronic properties of GeSe monolayers can be better described by using GGA(in the form of PW91)exchange association generals.The results of adsorption energy calculation show that O,Al and B atoms can be stably adsorbed on GeSe monolayer,and the comparison of the adsorption energy results shows that the most stable adsorption is O atom.According to the electronic structure calculation,the intrinsic GeSe is a p-type direct bandgap semiconductor.The impurity band generated by the adsorbed B,Al atom in the band gap changes the type of GeSe monolayer conductivity(from P-type conductivity to n-type conductivity).Adsorption atoms modulate the width of the band gap and the absorption edge of the light absorption of the GeSe monolayer.The results of optical properties calculation show that the adatoms affect the refractive index and extinction properties of GeSe monolayer,and regulate the optical absorption and reflection properties at the same time.Al adsorption enhanced the absorption of the whole spectral region from infrared to visible to UV region;B adsorption enhanced the optical absorption from visible to UV region.At the same time,B,Al adsorption will also enhance the reflection of light,especially in the UV region.Secondly,the effect of H2,O2or OH adsorption on the photoelectric properties of two-dimensional GeSe materials was investigated.H2,O2or OH can form stable adsorption in GeSe monolayer,and the adsorption formed by O2or OH is the most stable.Atomic doping and adsorption,molecular adsorption regulates the band gap and affects the absorption edge of GeSe monolayer light absorption.The analysis of band structure and state density shows that the absorption of O2and OH and the introduction of unoccted impurity state in the middle of the doping energy gap of P enhance the conductivity of GeSe monolayer semiconductor.The impurity state introduced by Al doping is close to the bottom of conduction band,indicating n-type conduction.GeSe monolayers adsorbed by H2,Al doped GeSe monolayers adsorbed by H or OH,and P doped GeSe monolayers adsorbed by H or OH have no impurity bands in band gap,resulting in a P-type semiconductor monolayer as pure GeSe monolayer.The calculation results of optical properties show that the absorption coefficient of GeSe monolayer adsorbed O2and doped P near the absorption edge is greater than that of undoped GeSe monolayer,indicating that the absorption capacity of GeSe monolayer in infrared region can be effectively improved by adsorbed O2or doped P.The reflectivity results show that O2or H2adsorption enhances the reflection of GeSe monolayer in ultraviolet region,which can be used for uv detection and protection.In addition,adsorption of H2,adsorption of OH,Al doping and P doping all enhance the absorption of visible and ultraviolet region of GeSe monolayer.In conclusion,our study provides a reliable theoretical basis for the application of GeSe two-dimensional materials in the field of optoelectronics. |
PDF Full Text Request