Optimizing the Synthesis of CVD Single Crystal Few-Layer h-BN for Graphene Electronic Devices

Summer 2017

Stanley Liu : Physics, Computer Science

Mentor: Alex Zettl

With the initial discovery and isolation of graphene in 2004, there have been many studies in other 2D materials. One such material is hexagonal boron nitride (hBN), otherwise known as “white graphene,” due to its structural similarity to graphene but electrically insulating qualities. hBN plays a unique role as a dielectric layer when paired with graphene, vastly improving charge carrier mobility and chemical stability. In order to optimize these effects, we need control over the properties of hBN films, including layer number, crystal size, and crystal quality. While chemical vapor deposition (CVD) synthesis of hBN has been the subject of intense research, the growth dynamics of few-layer single crystal hBN are still poorly understood. The purpose of my project is to investigate the role of growth conditions in CVD-grown hBN and observe how they impact the electrical properties of graphene-hBN heterostructure devices.

Based on preliminary data in the Zettl Group and existing literature, we propose multilayer hBN grows by an under-layer growth mechanism and is driven by condensation of dissolved precursor below as-grown material. Moreover, we believe that the surfacing of hBN is dependent on the cooling rate and hydrogen flow during the growth. My goal is to prove these growth mechanisms and optimize hBN films for graphene devices.

Thanks so much to the Rose Hills Foundation for funding my research this summer. The financial backing played an extremely important role in allowing me to focus on research and lab work. Being a part of the SURF community and seeing how much work everyone has put into their projects has given me newfound inspiration in my own aspirations to attend graduate school. I think that research is an important part of a student's education, and this experience has stoked the flames of my passion for discovery and exploration.