Experimental Study Of Dielectric Property In Toplogical Insulators And Perovskite At Terahertz Frequency

Two-dimensional perovskite nanosheets and topological insulators exhibit unique physical properties as the novel optoelectronic materials,providing a broader platform for next-generation optoelectronic devices.Studying and understanding the carrier dynamics and dielectric properties of those novel materials is the key point for further exploring their potential applications.In this paper,an optical pump terahertz probe?OPTP?system is used for in-depth research.The main content of this paper can be divided into the following three work.1.Inorganic perovskite nanosheets,as the low-dimensional form of traditional three-dimensional perovskite,have a better light absorption and chemical stability than three-dimensional perovskites,and have shown considerable strength in the field of photovoltaics and light-emitting devices.Based on the difference between two-dimensional perovskites and conventional perovskites,parameters such as carrier mobility,electron scattering rate,and carrier diffusion distance need to be further determined.Thus,we performed an OPTP test.The test results intuitively reflect the charge transfer between the nanosheets and the existence of energy transfer,and determine the mobility and other parameters of the nanosheet.2.Bi₂Se₃ is a typical three-dimensional topological insulator.Due to the protection of time-reversed symmetry,the Dirac electrons appearing on the surface of the material give the surface state a typical graphene-like property,and it is a typical semiconductor inside the material.naturally.As the only method that can simultaneously acquire surface signals and body signals,terahertz pump probe can effectively study the dynamic process of topological insulators.We used the 2,4,8,10 QLs Bi₂Se₃ grown by molecular beam epitaxy to demonstrate the topological phase transition of the material.3.The combination of metamaterials with perovskites to achieve the controllable terahertz modulation is an example of the use of semiconductors in the field of optoelectronics.Using the finite time domain difference method to design the superstructure and using the micromachining process to prepare samples,we realized the optical pumping control of the terahertz Fano resonance intensity.Thanks to the ultra-high quantum efficiency of perovskites,the device produces a response at very low light intensities.