Fabrication of quantum-dot devices in graphene

Abstract

We describe our recent experimental results on the fabrication of quantum-dot devices in a graphene-based two-dimensional system. Graphene samples were prepared by micromechanical cleavage of graphite crystals on a SiO₂/Si substrate. We performed micro-Raman spectroscopy measurements to determine the number of layers of graphene flakes during the device fabrication process. By applying a nanofabrication process to the identified graphene flakes, we prepared a double-quantum-dot device structure comprising two lateral quantum dots coupled in series. Measurements of low-temperature electrical transport show the device to be a series-coupled double-dot system with varied interdot tunnel coupling, the strength of which changes continuously and non-monotonically as a function of gate voltage.

• graphene
• quantum dots
• double quantum dots
• single-electron transport

Acknowledgments

We thank Taketoshi Fujita of MANA for technical support with the Raman spectroscopy measurements. This work was supported in part by the following: Nanotechnology Network Program, Grant-in-Aid for Exploratory Research (22656024), Grant-in-Aid for Scientific Research (B) (22360147), Grant-in-Aid for Young Scientists (B) (22740248) and the World Premier International Research Center (WPI) Initiative on Materials Nanoarchitectonics from the Ministry of Education, Culture, Sports, Science and Technology, Japan.