Study On Anisotropic Properties Of Black Phosphorus And Its Application In Photoelectric Detection

As a unique member of the two-dimensional material family,black phosphorus has some characteristic properties.For example,as a bridge between graphene and TMDCs,black phosphorus has adjustable band gap(0.3-2e V),high carrier mobility and considerable current switching ratio(up to 10⁵).The important feature of black phosphorus is the structural anisotropy,which makes it show unique anisotropy in optical,electrical,thermal and mechanical properties.More significantly,the band gap can be controlled in a wide range by the action of external field,which promotes the development and application of black phosphorus in photoelectric field.In this thesis,the research work is mainly focused on the photoelectric properties of the anisotropy of black phosphorus.And we studied the anisotropic properties of black phosphorus and the electrical and photoelectric properties of its heterojunction by using Raman spectrometer,semiconductor characteristic tester and laser.In this paper,multilayered black phosphorus flakes were synthesized via mechanical exfoliation from the bulk crystal,and field-effect transistors based on few-layer black phosphorus were fabricated by micro-nano fabrication technology,which owns 0°?360°four pairs of symmetrical electrodes.Polarization Raman spectra show that each intensity of the three characteristic peaks has a 180°periodic variations.On the other hand,the electric transport curves illustrate that the largest source leakage current can be obtained near 0°(180°)armchair direction.Such results indicate the anisotropy of black phosphorus.It indicate the anisotropy of black phosphorus.Furthermore,transfer curves with different electrode angles show that weak bipolar of black phosphorus at 45°(225°),90°(270°),and p-type performance at 0°(180°),135°(315°)can be offered,respectively.Gate voltage can effectively coordinate the output characteristics,and the modulate depth is much greater than 10².In addition,the photocurrent and photoresponse of the heterojunction photodetector show an opposite trend with the increase of power.The maximum photoresponse of the BP/graphene heterojunction photodetector is approximately 7.5×10^-2m A/W,and the BP/molybdenum disulfide photodetector is about 9.1×10^-2m A/W.