Charge-Transfer-Induced p-Type Channel in MoS2 Flake Field Effect Transistors.

The two-dimensional transition-metal dichalcogenide semiconductor MoS2 has received extensive attention for decades because of its outstanding electrical and mechanical properties for next-generation devices. One weakness of MoS2, however, is that it shows only n-type conduction, revealing its limitations for homogeneous PN diodes and complementary inverters. Here, we introduce a charge-transfer method to modify the conduction property of MoS2 from n- to p-type. We initially deposited an n-type InGaZnO (IGZO) film on top of the MoS2 flake so that electron charges might be transferred from MoS2 to IGZO during air ambient annealing. As a result, electron charges were depleted in MoS2. Such charge depletion lowered the MoS2 Fermi level, which makes hole conduction favorable in MoS2 when optimum source/drain electrodes with a high work function are selected. Our IGZO-supported MoS2 flake field effect transistors (FETs) clearly display channel-type conversion from n- to p-channel in this way. Under short- and long-annealing conditions, n- and p-channel MoS2 FETs are achieved, respectively, and a low-voltage complementary inverter is demonstrated using both channels in a single MoS2 flake.