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.