The Layered Selenides Reserch Of Photoelectric And Physical Properties

As a traditional thermoelectric material,Sb₂Te₃ and Bi₂Se₃ has been discovered was topological insulator in recent years.It has a new quantum state.More and more scientists are paying attention to topological insulators.In this paper,the single crystal Bi₂Se₃ film is grown on the P-type silicon substrate and InP substrate by Molecular Beam Epitaxy?MBE?technology and the single crystal Sb₂Te₃ film is grown on the P-type silicon substrate by physical vapor deposition.The crystal quality of the film was characterized by XRD technique and a simple device was assembled.The photoelectric properties of the heterojunction formed by the film and the substrate were studied.According to the photoelectric characteristics text resuilts of heterojunction,the external quantum efficiency of the heterojunction and the respond speed of the heterojunction are further studied.Then the physical explanation was inferenced according to the results.The results are as follows:Firstly,the single crystal Bi₂Se₃ film was prepared on P-type Si?111?substrate by MBE technique.Two different passivate modes were used on film grown.The crystal quality of the films grown on two passivate surfaces was studied and characterized by XRD technique.Studies have shown that two passivated mode can obtain single crystal Bi₂Se₃ film all,but single crystal Bi₂Se₃ film of Bi passivated has better crystal quality.The electrical and optics properties of the heterostructure formed by single crystal Bi₂Se₃ film and Si were tested.The test shows that the heterojunction has good diode characteristics,and the H-Si/Bi₂Se₃ heterojunction has photoelectric effect.On this basis,we have tested and got that the heterojunction photoelectric conversion efficiency is0.084%.The obvious external quantum efficiency appears between 800nm and 1200nm wavalength and the max external quantum efficiency reaches 14.7%at 1030nm.The max response speed of the heterojunction was determined to be 1ms and the physical explanation was got.Secondly,the single crystal Sb₂Te₃ films were prepared on H-passivated P-type Si?111?substrates by physical vapor deposition.The quality of single crystal Sb₂Te₃ films was characterized by XRD.Studies have shown that single crystal Sb₂Te₃ film can be obtained on an H passivated Si?111?substrate.The electrical and optical test of the heterojunction formed by single crystal Sb₂Te₃ film and Si shows that the H-Si/Sb₂Te₃heterojunction has typical diode characteristics and photoelectric effect.Photoelectric conversion efficiency of heterojunctionts is 0.072%.The external quantum efficiency of H-Si/Sb₂Te₃ heterojunction appeared between 800nm and 1200nm,and the max external quantum efficiency reached 15.5%at 1050nm.The max response speed of the heterojunction was determined to be 0.8 ms.Thirdly,the single crystal Bi₂Se₃ film was prepared on InP?111?A and InP?111?B substrates by MBE technology.It was found that it is difficult to obtain a cleaner surface of InP by conventional techniques.During the growth process,the crystal quality becomes higher with surface flatness increasing.The conclusion was confirmed by XRD techniques.Studies have shown that high quality single crystal Bi₂Se₃ films can be obtained on InP?111?A and InP?111?B substrates.The optical and electrical properties of the InP?111?A/Bi₂Se₃ heterojunction and the InP?111?B/Bi₂Se₃ heterojunction were tested.It can be seen that the two heterojunction connections are ohmic connections and there is no photoelectric effect.