Two-Dimensional Electronic Materials of the Future: Transition Metal Dichalcogenides

Transition Metal Dichalcogenides (TMDs) are two-dimensional materials of type MX2, where M is a transition metal and X is a chalcogen. TMDs boast a wide range of practical electronic applications. They have potential uses in high-end electronics such as field-effect transistors, flexible electronics, optoelectronics, and energy storage. Our research explores the material properties of lateral heterostructures of form MX2¬-MX2. The ability to mix-and-match various TMDs gives way to the concept of materials-by-design, where devices can be designed to meet very specific requirements for a certain task. While there has been prior research into lateral TMD heterostructures, we have yet to understand how the concentration of each material in the overall system effects the structure and formation energy. We use Density Functional Theory (DFT) calculations to explore the structural stability and formation energies of possible MX2-MX2 combinations. Preliminary results show that there might be a relationship between the molecular weight of a heterostructure and its formation energy. However, a more thorough and proper analysis of the data is needed. Future work involves exploring the relationship between band gap and atomic concentrations of our TMD heterostructures

First-Principles Study for ALD of MoS2

Atomic layer deposition (ALD) is a method for thin-film growth with atomic thickness control, with many applications in microelectronics. ALD is a cyclical process where the two precursors (MoF6 and H2S for MoS2) are never introduced simultaneously. In this study, we determined the role of surface hydroxyl groups (-OH) during MoF6 deposition on an Al2O3 surface, and we studied the reactivity of two other potential substrates, Si2N2O and TiO2. We used density functional theory (DFT) implemented by the Vienna ab Initio Simulation Package (VASP) to determine ground-state geometries and electron distributions of our modeled systems. Our results indicate that hydroxyl groups break the Al-O bonds, allowing the Al atoms to bond covalently with F atoms on MoF6. We see that the MoF6 can reduce to MoF5, MoF4, or MoF3, and these reduced oxidation states (+5, +4, or +3 respectively) may improve the deposition process. These results indicate that hydroxyl groups directly control the surface properties of Al2O3 by strengthening the interactions between Al atoms and F atoms on MoF6

Materials By Design: Carbon Capture

One third of CO2 emission in the United States is from fossil fuel power plants. Carbon dioxide capture techniques are to efficiently capture CO2 before it gets released into the atmosphere, and store it safely in the porous solid materials, as “CO2 containers”, Developing such “CO2 containers” is a crucial process, because the “containers” must have the abilities to separate CO2 from the flue gases, including CO2, O2, N2, CH4 , H2, He etc., store CO2 safely, as well as easily release CO2 for other applications. This project aims to leverage computational modeling techniques to design cost-effective and environmentally friendly porous solid materials for carbon dioxide capture.

Computational Modeling of 2D Transition Metal Dichalcogenides by Atomic Layer Deposition

Targeted theme is Advanced Devices, Packaging, and Materials. The goal of this project is to investigate atomic layer deposition (ALD) of two-dimensional (2D) transition metal dichalcogenides (TMDs) using computational modeling. Our objective is to screen precursors specifically MoCl2 (III) Me2NC(NiPr)2, MoCl4 (V) Me2NC(NiPr)2, and MoF6 and run a series of energetic calculations. This data will show us how stable and reactive our precursors are and help develop new precursors for growing TMDs using ALD. TMDs have great potential for logic, memory, opto-electronic, energy harvesting, energy storage, and thermal management applications and devices

Two-Dimensional Transition Metal Dichalcogenides (2D-TMDs) Studies via Computational Calculations

The research work behind Two-Dimensional materials, such as Graphene opens a new set of possibilities to the creation of these type of materials that will have the same or even better thermoelectrical properties than Graphene. The main example of these materials, are the two-dimensional transition metal dichalcogenides (2D-TMDs). These, then will be doped with different types of semiconductors or assembled in a vertical heterojunction; to later measure the interaction between the atoms in both process. Our objective is to develop, via computational calculations, the most stable and efficient set atoms that in the future could end up having very useful technological properties, such as sensors, communication systems, intelligent memory and much more