College of Science & Engineering
The Johns lab is exploring the role of surface chemistry in the CVD growth of highly crystalline, large area monolayers of metal chalcogenides starting with MoS2. Unlike graphene, monolayer MoS2 is a direct band gap semiconductor, and recent progress has been made improving its electrical performance and characterizing its optical properties. The researchers are attempting to use epitaxial relationships to grow large area, monolayer MoS2 via CVD on SiC and GaN. They characterize the growth process using scanning probe and optical spectroscopy, and they use density functional theory to understand the resultant electronic structure of the resultant interfaces and to interpret the spectroscopic results. They aim to both create more electronically and commercially relevant 2D materials and to better understand the chemistry and physics of Van der Waals growth processes. This knowledge will guide further attempts to use CVD to grow new monolayer-based materials including black phosphorus, germanane, and transition metal halides. Finally, the group has also discovered a chemically new nanowire based on Mo6Te6, and we are calculating the electronic and vibrational properties of this new metallic nanomaterial.
The group is also beginning to look at using deep learning models to predict spectra of molecules and materials based on a finite number of material properties. This effort is enhanced by using GPU clusters for model training.