A high-performance hydrogen sensor based on a reverse-biased MoS2/GaN heterojunction

Goel, Neeraj and Kumar, Rahul and Jain, Shubhendra Kumar and Rajamani, Saravanan and Roul, Basanta and Gupta, Govind and Kumar, Mahesh and Krupanidhi, S B (2019) A high-performance hydrogen sensor based on a reverse-biased MoS2/GaN heterojunction. In: NANOTECHNOLOGY, 30 (31).

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Abstract

We report a MoS2/GaN heterojunction-based gas sensor by depositing MoS2 over a GaN substrate via a highly controllable and scalable sputtering technique coupled with a post sulfurization process in a sulfur-rich environment. The microscopic and spectroscopic measurements expose the presence of highly crystalline and homogenous few atomic layer MoS2 on top of molecular beam epitaxially grown GaN film. Upon hydrogen exposure, the molecular adsorption tuned the barrier height at the MoS2/GaN interface under the reverse biased condition, thus resulting in high sensitivity. Our results reveal that temperature strongly affects the sensitivity of the device and it increases from 21% to 157% for 1% hydrogen with an increase in temperature (25-150 degrees C). For a deeper understanding of carrier dynamics at the heterointerface, we visualized the band alignment across the MoS2/GaN heterojunction having valence band and conduction band offset values of 1.75 and 0.28 eV. The sensing mechanism was demonstrated based on an energy band diagram at the MoS2/GaN interface in the presence and absence of hydrogen exposure. The proposed methodology can be readily applied to other combinations of heterostructures for sensing different gas analytes.

Item Type:	Journal Article
Publication:	NANOTECHNOLOGY
Publisher:	IOP PUBLISHING LTD
Additional Information:	Copyright of this article belongs to IOP PUBLISHING LTD
Keywords:	MoS2; 2D materials; heterojunction; hydrogen sensing
Department/Centre:	Division of Chemical Sciences > Materials Research Centre
Date Deposited:	23 May 2019 06:11
Last Modified:	23 May 2019 06:11
URI:	http://eprints.iisc.ac.in/id/eprint/62705

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