Rani Asha, DiCamillo Kyle, Krylyuk Sergiy, Debnath Ratan, Taheri Payam, Paranjape Makarand, Korman Can E, Zaghloul Mona E, Davydov Albert V
School of Engineering and Applied Science, The George Washington University, Washington, DC 20052, USA.
Department of Physics, Georgetown University, Washington, DC 20057, USA.
Proc SPIE Int Soc Opt Eng. 2018;10725. doi: 10.1117/12.2503888.
In this study, electronic properties of field-effect transistors (FETs) fabricated from exfoliated MoTe single crystals are investigated as a function of channel thickness. The conductivity type in FETs gradually changes from n-type for thick MoTe layers (above ≈ 65 nm) to ambipolar behavior for intermediate MoTe thickness (between ≈ 60 and 15 nm) to p- type for thin layers (below ≈ 10 nm). The n-type behavior in quasi-bulk MoTe is attributed to doping with chlorine atoms from the TeCl transport agent used for the chemical vapor transport (CVT) growth of MoTe. The change in polarity sign with decreasing channel thickness may be associated with increasing role of surface states in ultra-thin layers, which in turn influence carrier concentration and dynamics in the channel due to modulation of Schottky barrier height and band-bending at the metal/semiconductor interface.
在本研究中，对由剥离的碲化钼（MoTe）单晶制成的场效应晶体管（FET）的电学性质作为沟道厚度的函数进行了研究。FET中的导电类型从厚MoTe层（约65nm以上）的n型逐渐变化为中等MoTe厚度（约60至15nm之间）的双极性行为，再到薄层（约10nm以下）的p型。准块状MoTe中的n型行为归因于用于MoTe化学气相传输（CVT）生长的TeCl传输剂中的氯原子掺杂。随着沟道厚度减小，极性符号的变化可能与超薄层中表面态作用的增加有关，这反过来又由于肖特基势垒高度的调制和金属/半导体界面处的能带弯曲而影响沟道中的载流子浓度和动力学。
