Tunable Quantum Confinement in Individual Nanoscale Quantum Dots via Interfacial Engineering

Introducing quantum confinement has shown promise to enable control of charge carriers. Although recent advances make it possible to realize confinement from semiclassical regime to quantum regime, achieving control of electronic potentials in individual nanoscale quantum dots (QDs) has remained challenging. Here, we demonstrate the ability to tune quantum confined states in individual nanoscale graphene QDs, which are realized by inserting nanoscale monolayer WSe₂ islands in graphene/WSe₂ heterostructures via interfacial engineering. Our experiment indicates that scanning tunneling microscope (STM) tip pulses can trigger a local phase transition in the interfacial nanoscale WSe₂ islands, which, in turn, enables us to tune discrete quantum states in individual graphene QDs. By using a STM tip, we can also generate one-dimensional (1D) position-tunable domain boundaries in the WSe₂ islands. The 1D boundary introduces atomically wide electrostatic barriers that bifurcate quasibound states into two regions in the graphene QD, changing the QD from a relativistic artificial atom to a relativistic artificial molecule.