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Probing defect states in few-layer MoS2 by conductance fluctuation spectroscopy

Sarkar, Suman and Bid, Aveek and Ganapathi, K Lakshmi and Mohan, Sangeneni (2019) Probing defect states in few-layer MoS2 by conductance fluctuation spectroscopy. In: PHYSICAL REVIEW B, 99 (24).

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Official URL: https://dx.doi.org/10.1103/PhysRevB.99.245419

Abstract

Despite the concerted effort of several research groups, a detailed experimental account of defect dynamics in high-quality single-and few-layer transition-metal dichalcogenides remains elusive. In this paper we report an experimental study of the temperature dependence of conductance and conductance fluctuations on few-layer MoS2 exfoliated on hexagonal boron nitride and covered by a capping layer of high-kappa dielectric HfO2. The presence of the high-kappa dielectric made the device extremely stable against environmental degradation as well as resistant to changes in device characteristics upon repeated thermal cycling, enabling us to obtain reproducible data on the same device over a timescale of more than 1 year. Our device architecture helped bring down the conductance fluctuations of the MoS2 channel by orders of magnitude compared to previous reports. The extremely low noise levels in our devices made it possible to detect the generation-recombination noise arising from charge fluctuation between the sulfur-vacancy levels in the band gap and energy levels at the conductance band edge. Our work establishes conduction fluctuation spectroscopy as a viable route to quantitatively probe in-gap defect levels in low-dimensional semiconductors.

Item Type: Journal Article
Additional Information: copyright for this article belongs to AMER PHYSICAL SOC
Department/Centre: Division of Interdisciplinary Research > Centre for Nano Science and Engineering
Division of Physical & Mathematical Sciences > Physics
Depositing User: Id for Latest eprints
Date Deposited: 29 Jul 2019 11:47
Last Modified: 29 Jul 2019 11:47
URI: http://eprints.iisc.ac.in/id/eprint/63224

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