Evolution of various quantum transport properties in a suspended disordered graphene device by the high bias voltage exposure

Abstract

We investigated the evolution of the electronic transport properties of a suspended disordered graphene device by systematically controlling the bias voltage. Previously, the application of high bias voltage resulted in the sudden constriction of a graphene device. During the high bias voltage process, we utilized an electronic feedback loop to prevent the sudden change in resistance to ensure that the constriction proceeded sufficiently slowly. We performed a total of 137 sequential steps of a controlled high bias voltage exposure on the device in a cryostat. After each exposure, we measured the electronic transport properties and observed the transformation between various intriguing quantum transport phenomena. When the overall conductance was suppressed below approximately 10% of the single quantum conductance, superimposed Coulomb diamond patterns appeared at low temperatures, exhibiting parallel double quantum dot behaviors. We also found that the parallel double quantum dots were transformed into a single quantum dot and then into a single tunnel barrier as the high-voltage exposure was applied repeatedly. The transformation of the electronic transport properties along with the high bias voltage exposure processes can be attributed to the gradual reduction of the graphene width.