Photo-tunable transfer characteristics in MoTe2\u2013MoS2 vertical heterostructure

Arup Kumar Paul,Biswanath Chakraborty,Manabendra Kuiri,Anindya Das,Dipankar Saha,Santanu Mahapatra,A K Sood

doi:10.1038/s41699-017-0017-3

Arup Kumar Paul, Biswanath Chakraborty + Show 5 more

Open Access

https://doi.org/10.1038/s41699-017-0017-3

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Abstract

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.

Highlights

Van der Waals heterostructures based on transition metal dichalcogenides (TMDs) are being studied extensively, due to their excellent electronic and opto-electronic properties[1,2,3,4] with potential applications such as transistor,[5] photo detector,[6, 7] light-emitting diode (LED),[8,9,10] and solar cells.[11, 12]
To further elucidate the IDS–VBG curves, we have carried out the transport measurements with the exposure of light for blue, red (λ ~650 nm), and near IR (λ ~850 nm) LEDs on the D3 device
It was observed that the device response changed drastically with exposure of light, and even after LED was switched off the changes were retained for a long time ~24 h

Summary

Introduction

Sharp interfaces with intralayer high carrier mobility and lack of dangling bonds result in unique spatial charge separation[13] between the layers, as well as produce long-lived interlayer excitons[14] under light exposure These TMD-based vertical heterostructures have shown potentials as p–n junction and most of these p–n junctions show antiambipolar transconductance behavior.[15,16,17,18,19,20,21] p–n junction made of single layer of TMDs, known as atomically thin p–n junctions,[22,23,24,25] show quite different type of charge transport mechanism compared to the conventional p–n junction. The band engineering of vertical heterostructures[26] with available TMDs having different band gaps and work functions have paved the way to investigate the charge transport mechanisms in atomically thin p–n junction

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