Photo-tunable transfer characteristics in MoTe2–MoS2 vertical heterostructure

• Published in: NPJ 2D materials and applications Vol. 1; no. 1; pp. 1 - 7
• Main Authors: Paul, Arup Kumar, Kuiri, Manabendra, Saha, Dipankar, Chakraborty, Biswanath, Mahapatra, Santanu, Sood, A. K, Das, Anindya
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 27.06.2017; Nature Publishing Group; Nature Portfolio
• Subjects: 639/301/119/995; 639/766/119/995; Carrier transport; Charge transport; Chemistry and Materials Science; Current carriers; Current voltage characteristics; Density functional theory; Dissimilar materials; Electrical junctions; Electrical properties; Electronic devices; First principles; Heterojunctions; Heterostructures; Incident light; Interlayers; Materials Science; Molybdenum compounds; Molybdenum disulfide; Nanotechnology; Optoelectronic devices; P-n junctions; Room temperature; Surfaces and Interfaces; Tellurides; Thin Films; Transconductance; Transition metal compounds; Two dimensional materials
• ISSN: 2397-7132; 2397-7132
• DOI: 10.1038/s41699-017-0017-3

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 MoTe 2 (p)–single-layer MoS 2 (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 ~10 5  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 MoTe 2 –MoS 2 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. p–n junctions: unusual transfer characteristic p–n heterojunctions based on certain two-dimensional transition metal dichalcogenides display an unusual dip in the current–voltage characteristic. A team led by Anindya Das at the Indian Institute of Science in Bangalore fabricated p–n junctions made of few layers of MoTe 2 and a single layer of MoS 2 and observed an unexpected dip in the junction current as a function of the back gate voltage. The researchers could modulate the intensity and position of this dip feature by changing the power density of the incident light. They also performed theoretical calculations that qualitatively captured the behavior of the dip, which could be attributed to interface recombination of charge carriers. These findings further the understanding of the physics of thin-film interfaces, which can stimulate the improvement of devices.