Youngwoo Nam's Lab

Experimental Study on Electron Transport in Mesoscopic Systems

We experimentally study electron transport in mesoscopic systems using two-dimensional (2D) materials. 2D materials are crystals that are only one or a few atoms thick. Notably, these atomically thin crystals possess unique properties that differ drastically from those of the bulk, and exhibit new physical phenomena . Accordingly the field poses plenty of outstanding questions and unexplored domains. Our work will focus on topics that address these questions and domains with sophisticated device architectures controlled at the atomic scale and advanced transport measurement techniques.

Nano-fabrication

The well-controlled nano-fabrication stages enable the realization of sophisticated and high-quality devices at the atomic scale, which are highly necessary for observing intrinsic electron transport behaviors in a quantum limit.

Electrical Transport Measurements - electric field effect and quantum Hall effect

Electrical transport measurements in nanoscale devices of 2D materials demonstrate distinctive phenomena such as strong electric field-effect and quantum Hall effect. These are hallmarks of a 2D electron transport that are never seen in ordinary 3D bulk materials. In particular, 2D devices of the exceptionally highest quality allow the observation of electron-electron interaction effects. For instance, charge carriers in graphene multilayers are found to show behaviors associated with electron-hole scattering and electronic phase transitions originating from the interaction effects.

Thermal Transport Measurements - thermoelectric effect

Thermoelectric effects (also called TEP or Seebeck effect) allow the generation of electrical voltage (V) when temperature(T) difference is developed along two ends of the material . Remarkably, these effects are very sensitive to the change of the density of states near the Fermi energy and can accordingly be used as probes of the electronic structure at the nanoscale. Therefore this is a good complementary tool for the study of electron transport in 2D materials aside from conventional electrical measurements.

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