Multi-layer WSe2 field effect transistor with improved carrier-injection contact by using oxygen plasma treatment

Abstract This paper investigates the effect of an oxygen (O 2 ) plasma treatment on multi-layer tungsten diselenide (WSe 2 ) field-effect transistor (FET) by forming tungsten trioxide (WO 3 ) layers. Palladium (Pd), which is known to form an Ohmic contact with WSe 2 , is used for the source and drain (S/D) contact electrodes as a control group for metal variables. And then, Nickel (Ni), which is thought to form a Schottky contact with WSe 2 experimentally, is used as an experimental group. For both cases of the control group and the experimental group, the electrical characteristics including drain current ( I D ), on/off ratio ( I ON / I OFF ), subthreshold swing ( SS ) and field effect mobility ( μ eff ) are analyzed according to the presence or absence of WO 3 . In case of adopting the WO 3 contact layer between the WSe 2 and the Ni for the S/D contact electrode, we observe a remarkable improvement in I D , I ON / I OFF , μ eff , and SS compared to the case without the WO 3 contact layer. The analyzed electrical characteristics show that an efficient hole-injection contact was achieved for the multi-layer WSe 2 FET by the O 2 plasma treatment, which leads to the formation of an Ohmic-like contact at an electrode/WSe 2 interface.