Ionic liquid gate tunable diodes based on MoSe₂/doped Si hetero-junctions

We present our results on the fabrication and electrical characterization of CVD grown monolayer MoSe₂/doped Si heterojunction diodes at room temperature. Ionic liquid (IL) gating of monolayer MoSe₂ when connected in a field-effect transistor configuration shows that the charge transport is ambipolar. This motivated us to test the operation of MoSe₂/doped Si diodes fabricated separately using p- and n-doped Si substrates in the presence of an IL. By applying a gate voltage to the IL we were able to tune the diode parameters (i.e. rectification ratio, turn-on voltage and ideality parameter). Notable differences in the current-voltage (I-V) curves were observed depending on the type of doped Si that was used. Varying the gate voltage resulted in the diode exhibiting non-linear rectifying characteristics in the first and third quadrant of the I-V plot for the MoSe₂/p-Si diode, while the MoSe₂/n-Si diode exhibited non-linear rectifying behavior only in the third quadrant of the I-V plot. Electrostatic current control at low voltages enhances the diode’s functionality, making it useful in other applications besides rectification.