Quantum Confinement in Nano-devices

Since the discovery of graphene via mechanical exfoliation, it has been shown that the electronic properties of solids can undergo dramatic change when the material thickness is reduced to the atomic limit. Notably, even the band structures of single-layers and bi-layers can be distinctively different in both graphene and transition metal dichalcogenides (TMDs). Their exotic band structures are uniquely different from those in conventional 2DEGs. In particular, the broken inversion symmetry and strong spin-orbit interaction in semiconducting TMDs polarize spins in the opposite direction near the band edges of each valley. This combined valley-spin degree of freedom provides new platforms for exotic emergent quantum phenomena and possible quantum device application. With the help of electron-beam-defined local depletion gates, the system dimension can be further reduced to be mesoscopic, where relevant device dimensions become comparable to the electron wavelength. In such gate-defined nanostructures, gate-tunable quantization can be achieved while preserving and manipulating the quantum phase coherently. 

Electrical Control of Charged Carriers and Excitons in Atomically Thin Materials

Realize gate-controlled Coulomb blockade and demonstrate electrical control over charged excitons in atomically thin materials.

Ke Wang, Kristiaan De Greve, Luis A. Jauregui, Andrey Sushko, Alexander High, You Zhou, Giovanni Scuri, Takashi Taniguchi, Kenji Watanabe, Mikhail D. Lukin, Hongkun Park & Philip Kim, Nature Nanotechnology 13, 128-132 (2018)