Parameter control for enhanced peak-to-valley current ratio in a MoS2/MoTe2 van der Waals heterostructure

Abstract

The I_ds–V_ds properties of a van der Waals cross-junction of few layered MoS₂/MoTe₂ were investigated, and the physical device parameters were altered in order to transform the conduction mechanism from thermionic emission to interband tunneling. The pristine heterostructure demonstrated rectification behavior of typical p–n junction diodes, because of the p-type and n-type nature of MoTe₂ and MoS₂, respectively. Lowering the contact resistance between the metal and channel materials, by changing the electrode metals from Au to Pd and Ti, alone did not give rise to carrier conduction through the hetero-interband tunneling between MoTe₂ and MoS₂. In addition to the reduction in contact resistance, the chemical doping of MoS₂ using Benzyl Viologen (BV) achieves hetero-interband tunneling between MoTe₂ and MoS₂, which probably narrows the depletion layer by degenerating MoS₂. The peak-to-valley ratio of the tunneling current of the BV-doped heterostructure of MoS₂/MoTe₂ is about 4.8, which is comparable to that of the commercially available Si tunneling diode.