FOR Mentors

Mentor: Tev Kuykendall

Video Interview:

https://drive.google.com/file/d/12BmwiF_8TKkiJUAAuqO6kpbPEBh3RKll/view?usp=sharing

Group description:

In the Inorganic Facility of the Molecular Foundry, we develop methods for synthesis of compound semiconductors resulting in well controlled morphology and electronic structure. This can be achieved through band gap engineering in nanowire heterostructures, or energy level alignment in stacked assemblies of 2D materials. Using gas-phase methods allows us to realize arrays of 1D semiconducting heterostructures as well as approach synthesis of 2D materials with single layer precision. By harvesting the power of chemical vapor deposition and metalorganic chemistry our approach leads to realization of materials with optimized properties or exhibiting exotic behaviors. For example, bandgap engineered systems are a promising platform for the development of unconventional light emitting and energy harvesting devices through control of exciton generation and annihilation.

Division: Molecular Foundry Division

Project description:

Transition metal dichalcogenides (TMDs) are an interesting class of semiconductor materials due to their emergent properties when reduced to thin two-dimensional (2D) layers. While exfoliation and vapor phase growth produce extremely high-quality 2D materials, direct fabrication at wafer scale remains a significant challenge. In previously published results, we demonstrated a method that we call “lateral conversion,” which employs chemical conversion of a metal-oxide film to TMD layers by diffusion of precursor propagating laterally between lithographically defined silica layers, resulting in patterned TMD structures with control over the thickness down to a few layers. The intern will work on further development of this synthetic method. The synthesis has two distinct components: 1) Micro lithography and substrate preparation, and 2) sample annealing and conversion to the resulting TMD. The intern will focus on processing lithographically patterned substrates using chemical vapor deposition (CVD) under a variety of conditions to optimize the growth strategy and control their morphology and crystalline quality. The main goal of the internship is to explore and optimize different synthetic conditions for growing 2D TMD semiconductor films. They will study the effect of precursor conditioning, pressure, temperature, and reactive gasses on the TMD growth. Using a variety of characterization techniques, they will narrow down the process, through successive experiments and characterization, to control size, thickness, and size distribution, producing high-quality TMD materials.

Intern’s role:

• The intern will learn how to conduct independent research on solid state materials synthesis.

• You will be responsible for synthesizing 2D TMD films using a two-step “lateral conversion” synthesis method.

• You will learn how to characterize the samples using a variety of synthetic and analytic techniques.

• You will learn how to interpret results, and make improvements to the synthetic process using feedback for successive experiments.

They will receive careful oversight and training during the first month, until they are qualified to work independently. Additional training will be given as needed. Regular discussions will be had to interpret results and gauge their progress.

What can the intern expect to learn?

They will learn a variety of synthetic and analytic techniques, such as:

• Chemical vapor deposition (CVD) synthesis

• Raman spectroscopy

• Optical microscopy

• You will learn about the lithographic process and microfabrication techniques

• You will be mentored in the creation of a final poster project and will learn how to present their data using written text, plots, photographic images, and illustrations.

Mentor name: Kristin A. Persson. Co-mentors Rishabh D. Guha, Alex Epstein

Video Interview:

https://drive.google.com/file/d/1f2vLiWVY9K_-FBPVJ3spI_-EdvLoRnpu/view?usp=sharing

Group description:

We work in the Persson Group supervised by Dr. Kristin Persson. Our group works on multiple connected areas which strives to use computational and statistical tools to understand the chemical and physical behavior of materials - https://perssongroup.lbl.gov

Division: Materials Science Division

Project description:

The accumulation of plastic waste is one of the critical environmental challenges the world is facing. One important route to solving this waste problem is to make plastics that are easy to recycle into new products that are just as good as the original. In our research group, we use simulations on the atomic scale to help design plastics that can be recycled through a chemical process where they are deconstructed in strong acid. One outstanding question in this process is: why do different acids drastically change the rate of recycling? In this project, we will use molecular simulations to study how different acids ionize the plastic at different rates, and their subsequent effects on the overall recycling rate.

Intern’s role:

• Prepare molecular dynamics simulations by expanding on existing Python code

• Submit and manage simulations on a supercomputing cluster

• Statistically analyze molecular dynamics simulations by writing Python code

• Meet with co-mentors at least once a week, but feel free to meet as much as needed

• Present short (5-10 min) presentations in bi-weekly meetings with our research group

What can the intern expect to learn?

• How to implement Python packages into their own scripts for preparing and analyzing molecular dynamics (Pymatgen, SolvationAnalysis, MDAnalysis)

• How to run molecular dynamics simulations with OpenMM

• How to use the supercomputing facilities at LBNL to design and submit jobs

• How to analyze and interpret large amounts of data to form concise conclusions