Graphene Circular p-n Junction: from Optical Guiding to Quantum Dot Physics*

The miniaturization limits on traditional semiconductor-electronics have led to proposals of an alternative platform based on the photon-like propagation of the Dirac-electrons in graphene. However, the chiral nature of these carriers and the associated Klein tunneling makes it difficult to control their motion electrostatically with standard gate voltages. We have devised a local dual-gate technique that produces a circular graphene p-n junction whose size can be continuously tuned from the nanometer-scale, where quantum effects are dominant, to the micrometer scale where optical-guiding takes over¹. By varying the parameters of the junction we investigate the mechanism of gate controlled trapping, detrapping and guiding of electrons. Furthermore, applying an external magnetic field enables us to study the crossover from Landau quantization to quantum dot physics and electron lensing.
¹Y. Jiang, et al, Tuning a Circular p-n Junction in Graphene from Quantum Confinement to Optical Guiding, Nature Nanotechnology (2017) doi:10.1038/nnano.2017.181