Investigations Of Two Dimensional Materials Black Phosphorus With Electrical And Optical Properties For Infrared Terahertz Wave Generation

Since the two dimensional mater ials have been discovered,extensive studies have been conducted due to the applications of two dimensional materials have a big potential for electronic and optical device.The two-dimensional mater ial has unique phys ical properties,which are also associated with their layered structure.For instance,the superconductivity of two-dimensional electron gas,the anisotropy of transmission characteristics,and so on.This paper briefly describes the present situation of the electronic and optical properties in two dimensional materials.And then combined with the Poisson equation and continuity equation of electron / hole,and the drift diffusion equations,the ambipolar electrical properties of black phosphorus field effect transistor(FET)are discussed.Finally,the absorption properties of terahertz radiation in monolayer black phosphorus device are discussed based on Finite-Difference Time-Domain.The results are list as follows:First,this paper considers the bulk black phosphorus FET,when Schottky barrier for electrons and holes is the same.And we discuss how the change of channel length affects the ambipolar behavior in black phosphorus FET.The ambipolar characteristics of the black phosphorus FETs become more and more obvious as the channel length become shorter.Then we analys is the band diagram of the 100 nm channel length and 2 ?m channel length of the transistor.The result shows that the switch mechanism of the ambipolar in black phosphorus FET is related to the channel length and is influenced by the height of the Schottky barrier.Second,next discuss the influence of the layer thickness and the height of the Schottky barrier on the ambipolar characteristic of the black phosphorus FET.When the Schottky barrier is the same as electrons and holes,the ambipolar properties of the FETs with different layers of black phosphorus become more and more obvious with the shorter channel length.And at this time,the output current increases with the increase of the layer thickness of black phosphorus.Then the distribution of electric potential and the distribution of electron concentration in the black phosphorus FET are studied.And how the Schottky barrier height,layer thickness,and the channel length effect on the output characteristics,including carrier inject and ambipolar characteristics are discussed.Third,the variation of the different layer thickness and the different channel length of the black phosphorus FET are studied when the Schottky barrier heights are changed.When the Schottky barrier height for the hole is 0.24 e V,the monolayer black phosphorus transistor is unipolar,and with the increase of the number of layers,the current on/off ratio can be changed from 1010 to 103.Fourth,a monolayer black phosphorus device with nanoribbon structure is studied.And it is proved by numerical calculation that the local surface plasmon can be motivated in monolayer black phosphorus device.The optical absorption spectra and transmission spectra of monolayer black phosphorus in the terahertz range are also discussed.The relationship between the resonance frequency and the width of black phosphorus nanoribbon,the absorption rate and the width of black phosphorus nanoribbon are studied.It is found that the frequency of the absorption peak of the terahertz radiation in the device becomes smaller when the width of the black phosphorus nanoribbon becomes larger.In the end,the influence of the polar ization of inc ident light on the plasma oscillation is discussed.The position of the resonance frequency of monolayer black phosphorus nanoribbon device basically not change with the polarization direction of the incident light,but the peak absorption rate has changed obviously.The result shows that with the increase of the polarization angle the absorption rate decreased gradually.