Temperature and barrier height tunable current mechanism of a reverse-bised graphene-WS₂ barristor junction

In traditional semiconductor physics, the reverse-bias current of the Schottky junction is composed of the thermionic emission (TE) current and the Fowler-Nordheim tunneling (FNT) current; both are regarded as fixed. In this study, we studied the evolution of the reverse-biased current of the graphene-WS₂ junction barristor device by varying the barrier height and temperature. It originated from the barristor being a barrier-height-tunable device and temperature varying the doping level of the semiconductor, resulting in the modulation of the barrier thickness. As the barrier height decreases with electrons on graphene, the dominant transport mechanism of the junction changes from TE to FNT. As the temperature increases, the doping concentration of the WS₂ increases, and thus the barrier thickness decreases, resulting in the same evolution of the dominant transport. In addition, we observed the kink of the I_D-V_D curves at a specific range of gate voltage and temperature. It could originate from the alignment of the Fermi level of graphene near the Dirac point, which dramatically reduces the FNT current.