Quantum transport through MoS constrictions defined by photodoping.

We present a device scheme to explore mesoscopic transport through molybdenum disulfide (MoS) constrictions using photodoping. The devices are based on van-der-Waals heterostructures where few-layer MoS 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 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/hBN heterostructure. Low temperature two- and four-terminal transport measurements show evidence of quantum confinement effects.