Gate modulation of barrier height of unipolar vertically stacked monolayer ReS₂/MoS₂ heterojunction

This study investigates vertically stacked CVD grown ReS₂/MoS₂ unipolar heterostructure device as Field Effect Transistor (FET) device wherein ReS₂ on top acts as drain and MoS₂ at bottom acts as source. The electrical measurements of ReS₂/MoS₂ FET device were carried out and variation in Ids (drain current) Vs Vds (drain voltage) for different Vgs (gate voltage) revealing the n-type device characteristics. Furthermore, the threshold voltage was calculated at the gate bias voltage corresponding to maximum transconductance (g_m) value which is ~ 12 V. The mobility of the proposed ReS₂/MoS₂ heterojunction FET device was calculated as 60.97 cm² V^-1 s^-1. The band structure of the fabricated vDW heterostructure was extracted utilizing ultraviolet photoelectron spectroscopy and the UV-visible spectroscopy revealing the formation of 2D electron gas (2DEG) at the ReS₂/MoS₂ interface which explains the high carrier mobility of the fabricated FET. The field effect behavior is studied by the modulation of the barrier height across heterojunction and detailed explanation is presented in terms of the charge transport across the heterojunction.