Preparation And Optoelectronic Properties Of Selenide Bi₂Se₃ Thin Films

CdSe belongs to group II-VI semiconductor compound with the band gap E_g=1.74eV.It has excellent photoelectronic properties in the visible band of solar spectrum which has been widely used in infrared detectors,laser devices,solar cells and so on.Bismuth chalcogenides materials Bi₂Se₃ is in the series of V2VI3semiconductors with an excellent anisotropic layered structure and and gap ranges from 0.9-2.3 eV.These two kinds of selenides have good optoelectronic properties,and the formation of composite thin films may effectively improve the photoelectric properties of thin films,which is worthy of our further discussion through experiments.1.Bi₂Se₃ thin films and CdSe thin films were prepared by vacuum thermal evaporation equipment,and the data obtained by basic characterization methods.The results show that the CdSe thin films prepared by thermal evaporation equipment have good crystallization properties and grow along the?002?crystal direction,the surface of the films are uniform and smooth,and the grain size is less than 20 nm.CdSe semiconductor thin films Prepared by the experiment that the optical band gap is 2.1 eV.By comparing the XRD patters of Bi₂Se₃ thin films in the unannealed and annealed state,it is shown that the Bi₂Se₃ thin films prepared by thermal evaporation is polycrystalline,and the diffraction peak is the strongest along the?015?direction after annealed.2.When the vacuum reaches 5×10^-4 Pa,the voltage-current of Bi₂Se₃ films annealed for two hours increases linearly under light condition,and the response ability of transient photocurrent is stable.3.Bi₂Se₃/CdSe thin films were got by evaporate two compounds at the same time,the crystal orientation of Bi₂Se₃?015?and CdSe?002?can be clearly seen by X-ray diffractometer.Through the scanning electron microscope observation,it is found that there is a large aggregation of particles on the surface,and the surface is relatively rough,which is due to the influence of the lattice mismatch of the two selenides,annealing can effectively improve the surface morphology;the optical band gap of the composite films is smaller than that of pure CdSe films.