Motivation:

The successful exfoliation and characterization of graphene has led to interest in 2D materials. The application of these materials in semiconductors would give rise to faster, smaller, and more flexible devices and photovoltaics. Transition metal dichalcogenides (TMDs) are 2D materials of the form X-M-X, where the transition metal, M (Mo, W, etc.), is sandwiched between two chalcogenide atoms, X (S, Se, etc.).

We use synchrotron X-ray radiation techniques to understand the thin film growth of these materials, which will enable us to better incorporate them into next-generation devices.

Synchrotron X-ray techniques:

We employ a custom-built ultra-high vacuum (UHV) chamber, wherein we can deposit thin films with both a supersonic molecular beam and an effusive source.

In the G3 station at the Cornell High Energy Synchrotron Source (CHESS), we use X-rays to study the growth of thin films in situ and in real time.

X-ray reflectivity (XRR) at the anti-Bragg condition enables us to determine if a thin film grows layer-by-layer (LbL) or as 3D islands, and gives insight into the kinetics of thin film growth. X-ray fluorescence (XRF) allows us to probe chemical composition of the thin film during growth.