Research On Semiconductor SiC/InSe And InSb/InSe Heterojunctions

With the vigorous development of nanotechnology,two-dimensional(2D)materials have shined in the field of semiconductor materials due to their highly anticipated rich characteristics and broad application prospects.The advancement of semiconductor devices and research fields puts forward higher requirements for the application properties of 2D materials,and the shortcomings of the performance of a single material limit the pace of its development.The heterojunction formed by the vertical assembly of different 2D materials just solves this problem.The design and preparation of low-dimensional heterojunctions are the frontiers of the current research field,and it is also an ideal platform for the research of a new generation of semiconductor devices with excellent application characteristics and potential application prospects in the future.It is also necessary to consider the regulation of material properties by the external field in addition to the excellent characteristics of the material itself.Therefore,based on density functional theory,this thesis designs and explores the related structure and electronic properties of the new SiC/InSe and InSb/InSe heterojunctions from the perspective of the first-principles.Additionally,the focus is on the changes of their controllable band structure under external electric fields and strains.Achieved results with the important reference value,mainly as follows:The tunable electronic characteristics of the SiC/InSe heterojunction are investigated using an external vertical electric field and biaxial strain.According to our findings,the SiC/InSe heterojunction,with an intrinsic Type-II band alignment,effectively accelerates the effective spatial separation of photogenerated carriers with the lowest energy at the interface.Under an electric field,a distinct Stark effect is observed in the band gap.When a sufficiently large electric field is applied,the band gap is even closed,and the heterojunction achieves the transition to the metallic state.Besides,under a suitable tensile strain,a narrow band gap and a low carrier effective mass are obtained in the heterojunction.More interestingly,at 8%compressive strain,the heterojunction abruptly changes to a direct band gap from an indirect band gap.Taken together,based on results in this work,the SiC/InSe heterojunction provides a new way of thinking for the application of optoelectronics and microelectronics in the future.A stable InSb/InSe heterojunction is constructed by combining the InSb nanosheet and the InSe monolayer,and the regulation effects of external electric field and uniaxial strain on its electronic features are systematically investigated.According to our results,the InSb/InSe heterojunction has a direct band gap,which is an intrinsic Type-II band alignment,leading to a clear spatial separation of photogenerated electron-hole pairs.When a vertical electric field is applied,a unique Stark phenomenon appears in the band gap.Interestingly,such heterojunction is instantly converted to Type-I from Type-II at-0.3 V/(?).Moreover,the band gap is also effectively controlled by the uniaxial strain.Especially,under a compressive strain of 4% on the Y-axis,the heterojunction possesses a high carrier mobility.To sum up,findings in this research demonstrate that,the InSb/InSe heterojunction has great potential in the application of nanoelectronic and optoelectronic devices.