Electrical and Computer Engineering

Dissertation Defense

Chemical vapor sensing, physisorption, and separation on graphene

Wenzhe Zang
Phoenix Memorial Laboratory 2000AMap


Chemical vapors are ubiquitous in our daily life, which can be human-made or naturally occurring. Understanding and electrically tuning of vapor molecule-surface interaction can have profound impact on fundamental surface physics and usher breakthroughs in the development of new materials and novel sensing techniques. Graphene-based nanoelectronics systems offer a great platform to study such interactions due to the large surface-to-volume ratio, unique electronic properties, and low power consumption. Especially, the linear band dispersion in graphene enables continuous gate tunability of chemical potential to further influence its interaction with the adsorbate molecules.

In this thesis, I will first introduce a novel nanoelectronic sensing technology by exploiting the incomplete screening effect due to the semi-metallic nature of graphene. Rapid (sub-second) and sensitive (sub-ppb) detection of both polar and non-polar analytes is achieved, representing orders of magnitude improvement over state-of-the-art nanoelectronic sensors. Electrical probing and tuning of molecular physisorption on graphene were also demonstrated by using the as-developed sensor as testbed. Lastly, by leveraging graphene’s gate tuning effect, we developed an ultra-compact gas chromatography system with graphene as electrically tunable stationary phase. Fast, efficient, and electrically tunable vapor molecules separation is achieved on monolayer graphene surface with extremely low power consumption.

Chair: Professor Zhaohui Zhong