Tunable Quantum\nConfinement in Individual Nanoscale\nQuantum Dots via Interfacial Engineering

Introducing quantum confinement has shown promise to\nenable control\nof charge carriers. Although recent advances make it possible to realize\nconfinement from semiclassical regime to quantum regime, achieving\ncontrol of electronic potentials in individual nanoscale quantum dots\n(QDs) has remained challenging. Here, we demonstrate the ability to\ntune quantum confined states in individual nanoscale graphene QDs,\nwhich are realized by inserting nanoscale monolayer WSe<sub>2</sub> islands in graphene/WSe<sub>2</sub> heterostructures via interfacial\nengineering. Our experiment indicates that scanning tunneling microscope\n(STM) tip pulses can trigger a local phase transition in the interfacial\nnanoscale WSe<sub>2</sub> islands, which, in turn, enables us to tune\ndiscrete quantum states in individual graphene QDs. By using a STM\ntip, we can also generate one-dimensional (1D) position-tunable domain\nboundaries in the WSe<sub>2</sub> islands. The 1D boundary introduces\natomically wide electrostatic barriers that bifurcate quasibound states\ninto two regions in the graphene QD, changing the QD from a relativistic\nartificial atom to a relativistic artificial molecule.