Erasable High Mobility Two-dimensional Electron Gas At The Oxide Interface

Since the discovery of two-dimensional electron gas at the interface of LaAlO₃/SrTiO₃?LAO/STO?in 2004,the core concepts of traditional semiconductor devices,such as two-dimensional electronic gas and field effects,are being realized in the form of complex oxides,and the application of high-mobility devices with novel physical phenomena in the field of functional electronics has attracted extensive attention.Thin films and heterostructures based on SrTiO₃can obtain high mobility carriers by interface polarization,cation replacement and oxygen vacancy injection.However,the carrier obtained by the above method is difficult to modulate and realize erasable.The carrier can be regulated by surface ion bombardment,ion liquid electric double layer and probe scanning with external pressure,but it will damage the surface or be difficult to preserve,so it cannot meet the requirements of practical application.In this paper,a novel solution is proposed,which is to precisely and repeatably regulate the concentration of oxygen vacancy at the interface through ion channels that can be opened and closed freely,so as to modulate the high mobility and erasable two-dimensional electron gas at the oxide interface.Main achievements are as follows:?1?Propose new design idea of utilizing the difference of the formation energies and diffusion barriers of oxygen vacancies in the oxide heterostructure to achieve erasable and regulable concentration of oxygen vacancies and carriers at the interface by opening and closing the channels from which oxygen atom can escape through annealing at high temperature in vacuum.Combined with the first-principle calculation,utilizing that the formation energies and diffusion barriers of oxygen vacancies in layered oxide Sr_n+1Ti_nO_3n+1?RP?are higher than that of SrTiO₃,and formation energies and diffusion barriers of oxygen vacancies can be regulated by n index,so as to achieve the accurate regulation of two-dimensional electron gas with high mobility at the interface;?2?A series of high-quality Sr_n+1Ti_nO_3n+1/SrTiO₃samples were prepared by using oxide molecular beam epitaxy technology through optimizing the growth conditions.The opening and closing of ion channels in RP layer under different annealing conditions were systematically studied to obtain the regulation of oxygen vacancy and carrier concentration at SrTiO₃interface,and the carrier mobility was exceeding5.5×10⁴cm²V^-1s^-1.At the same time,the opening and closing of the oxygen ion channel in the vacuum and oxygen atmosphere is used to realize the repeatable erasing of the two-dimensional electron gas with high mobility,which meets the demand of the reusable of modern electronic devices and makes its application in the new electronic functional devices with high mobility possible;?3?Oxide molecular beam epitaxy growth technology has been improved.The stability of single crystal substrate temperature has an important effect on the quality of epitaxial films.By improving the blackness of the endothermic coating on the back surface of the single crystal substrate,the stability of the substrate temperature and the quality of the film has been improved.