| As a new member of two-dimension(2D)materials,black phosphorus possesses a lot of characteristics in electronics field which lacked in graphene and transitional metal dichalcogenides(TMDCs),including tunable bandgap(0.3–2.0 eV),high carrier mobility(1000 cm2 V-1 s-1)and decent on-off ratios(105).Based on these,field effect transistor which employed black phosphorus as channel materials would possess some superior electrical performances.However,there is much terra incognita that needs further exploration in the practical application of the black phosphorus field effect transistor because it is known to us for a short time,such as the black phosphorus field effect transistor regulation and reliability problem and so on.In this paper,the phonon scattering and electrical characteristics of black phosphorus field effect transistors are elaborated.The effects of internal stress on the performances of black phosphorus field effect transistor are discussed.And the breakdown behavior of black phosphorus field effect transistor and the stability in the atmospheric environment are explored.Black phosphorus samples were prepared by mechanical stripping method.The preparation of the substrate is based on reactive ion etching(RIE)techniques.TiW/Au electrode was deposited before RIE.Finally,black phosphorus flake is transferred to the substrate to complete the preparation of the transistor.This method can avoid the introduction of contamination during the deposition of electrodes on black phosphorus films,ensuring optimum performance of black phosphorus.The black phosphorus field effect transistor of 300 nm gate dielectric based on the above method was tested by Raman spectroscopy and semi-automatic probe station.The three Raman characteristic peaks of Ag1,B2 g and Ag2 of black phosphorus are obvious.There are no other peaks,indicating that black phosphorus structure is complete and possess primitive characteristics.The electrical test results show that the output characteristics of the transistor are linear.Gate voltage can effectively coordinate the output characteristics.The transfer characteristics of the transistor shows that holes play the part of the main carrier with the bipolar polarity characteristics.This device is mainly for the p-type characteristics.The square holes on the SiO2/Si substrate which processed by RIE technology suspend black phosphorus flake from substrate.This method effectively introduces tensile stress into the transistor.Raman spectroscopy showes that the Ag1,B2 g and Ag2 peaks of the black phosphorus film inside the square hole have different degree of redshift.Ag1 peak is most sensitive to stress strain.Subsequently,the electrical characteristics of the device were tested.Internal stress has little effect on its output characteristics.The carrier mobility of this transistor is calculated to be 347.5 cm2V-1s-1 from the transfer characteristics curve.Suspension method can effectively coordinate the performance of black phosphorus field effect transistor.But the thin gate dielectric is prone to breakdown of transistor.When the transistor is breakdown,electrical characteristics have qualitative changed.The device does not possess the properties of transistor and becomes a Schottky diode.The output characteristics of this device are parallel to each other at different gate voltages.Transistor has electricity leakage phenomenon.The transfer characteristic curve manifests that device is a one-way conduction state.The performances of black phosphorus field effect transistor at the time of preparation and exposure in the air for one month are tested,respectively.By using the light microscope can we observe the black phosphorus surface formed a "water droplets" thing and the thickness of black phosphorus is thinning.The three Raman peaks of the black phosphorus show blue-shift after exposure to air for a month.The resistance of transistor becomes larger.On-off ratio and carrier mobility of this device are both become smaller. |
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