PhD Defense by Yiran Hu

Physics PhD Thesis Defense

Date: May 8th 2020

Time: 1:00 PM

Bluejeans: https://bluejeans.com/172026843

Committee Members:

Walter de Heer, PhD (Advisor)

School of Physics, Georgia Institute of Technology

Zhigang Jiang, PhD

School of Physics, Georgia Institute of Technology

Markus Kindermann, PhD

School of Physics, Georgia Institute of Technology

Phillip First, PhD

School of Physics, Georgia Institute of Technology

Bernard Kippelen, PhD

School of Electrical and Computer Engineering, Georgia Institute of Technology

Title: GRAPHENE ON NON-POLAR SIC FACETS

Abstract: Graphene nanoribbons (SW-GNR) grown on sidewall SiC substrate facets exhibit exceptional quantized ballistic transport over 15μm even at room temperature. For micron long ribbons, transport in these charge neutral ribbons involves a single conducting channel with a conductance of e2/h, which to this day is not fully understood. We have therefore studied here graphene grown on SiC full wafers cut along the same crystallographic orientation as the sidewall facets. We characterize graphene growth on these non-conventional (non-polar) faces and identify preferred orientation and the presence of an interface layer. Transport measurements of Hall-bar patterned graphene devices shows strong similarities with that of SW-GNR ribbons. In particular, an analysis in terms of edge and bulk electronic states reveal a ballistic edge state conduction, with mean free path larger than 10μm, and a bulk conduction with a ~10nm mean free path. Segment quantization is also discussed. The findings in this thesis point to a new route towards future large scale high-performance electronics.