A vertical WSe₂-MoSe₂ p-n heterostructure with tunable gate rectification

Here, we report the synthesis of a vertical MoSe₂/WSe₂ p-n heterostructure using a sputtering-CVD method. Unlike the conventional CVD method, this method produced a continuous MoSe₂/WSe₂ p-n heterostructure. WSe₂ and MoSe₂ back-gated field effect transistors (FETs) exhibited good gate modulation behavior, and high hole and electron mobilities of ∼2.2 and ∼15.1 cm² V^-1 s^-1, respectively. The fabricated vertical MoSe₂/WSe₂ p-n diode showed rectifying I-V behavior with back-gate tunability. The rectification ratio of the diode was increased with increasing gate voltage, and was increased from ∼18 to ∼1600 as the gate bias increased from -40 V to +40 V. This is attributed to the fact that the barrier height between p-WSe₂ and n-MoSe₂ is modulated due to the back-gate bias. The rectification ratio is higher than the previously reported values for the TMDC p-n heterostructure grown by CVD.