Quantum transport through MoS$_2$ constrictions defined by photodoping

TL;DR

This paper introduces a novel device scheme using photodoping to study quantum transport in MoS$_2$ constrictions, revealing quantum confinement effects in mesoscopic structures.

Contribution

It demonstrates a new method to define and investigate MoS$_2$ constrictions via photodoping in van-der-Waals heterostructures, enabling exploration of quantum transport.

Findings

Evidence of quantum confinement effects in MoS$_2$ constrictions

Successful use of photodoping to induce charge carriers in insulating MoS$_2$ devices

Development of a device architecture for mesoscopic transport studies

Abstract

We present a device scheme to explore mesoscopic transport through molybdenum disulfide (MoS$_2$) constrictions using photodoping. The devices are based on van-der-Waals heterostructures where few-layer MoS$_2$ flakes are partially encapsulated by hexagonal boron nitride (hBN) and covered by a few-layer graphene flake to fabricate electrical contacts. Since the as-fabricated devices are insulating at low temperatures, we use photo-induced remote doping in the hBN substrate to create free charge carriers in the MoS$_2$ layer. On top of the device, we place additional metal structures, which define the shape of the constriction and act as shadow masks during photodoping of the underlying MoS$_2$/hBN heterostructure. Low temperature two- and four-terminal transport measurements show evidence of quantum confinement effects.