Photo-tunable transfer characteristics in MoTe2–MoS2 vertical heterostructure

Fabrication of the out-of-plane atomically sharp p–n junction by stacking two dissimilar two-dimensional materials could lead to new and exciting physical phenomena. The control and tunability of the interlayer carrier transport in these p–n junctions have a potential to exhibit new kind of electronic and optoelectronic devices. In this article, we present the fabrication, electrical, and opto-electrical characterization of vertically stacked few-layers MoTe2(p)–single-layer MoS2(n) heterojunction. Over and above the antiambipolar transfer characteristics observed similar to other hetero p–n junction, our experiments reveal a unique feature as a dip in transconductance near the maximum. We further observe that the modulation of the dip in the transconductance depends on the doping concentration of the two-dimensional flakes and also on the power density of the incident light. We also demonstrate high photo-responsivity of ~105 A/W at room temperature for a forward bias of 1.5 V. We explain these new findings based on interlayer recombination rate-dependent semi-classical transport model. We further develop first principles-based atomistic model to explore the charge carrier transport through MoTe2–MoS2 heterojunction. The similar dip is also observed in the transmission spectrum when calculated using density functional theory–non-equilibrium Green’s function formalism. Our findings may pave the way for better understanding of atomically thin interface physics and device applications.