Project Info
*Controlling impurity phases in silicon clathrate for energy applications and quantum information science
Prof. Carolyn Koh, Chemical and Biological Engineering, ckoh@mines.edu
Prof. Reuben Collins, Physics, rtcollin@mines.edu
The microelectronics and PV industries are crystalline silicon-based. They use silicon in the diamond crystal form. Silicon can, however, form other crystal structures with potentially better optoelectronic properties. In silicon clathrate, the silicon atoms form cages. This material has a higher energy gap than diamond silicon and a much larger absorption coefficient making it an interesting solar cell absorber. In addition, atoms such as Na which can be placed inside the cages as "guests" are potential qubits for use in quantum information science. These guest sites are also interesting for battery applications. As a new material, however, synthesis of silicon clathrate is in its infancy and it is difficult to produce the quality required for these applications. This project focusses on just that, removing impurity phases from silicon clathrate to create higher quality material and measurements to verify the improvements leading to results which can be tested in energy and computing applications.
More Information:
Grand Challenge: Make solar energy economical
These are publications on silicon clathrates by the team (W. Schenken was an undergrad researcher):
1. W.K. Schenken, Y. Liu, L. Krishna, A.A.A. Majid, C.A. Koh, P.C. Taylor, R.T. Collins, "Electron paramagnetic resonance study of type-II silicon clathrate with low sodium guest concentration," Physical Review B. 101, 245204 (2020). http://dx.doi.org/10.1103/PhysRevB.101.245204
2. L. Krishna, L.L. Baranowski, A.D. Martinez, C.A. Koh, P.C. Taylor, A.C. Tamboli, E.S. Toberer, "Efficient route to phase selective synthesis of type II silicon clathrates with low sodium occupancy," CrystEngComm. 16, 3940-3949 (2014). http://dx.doi.org/10.1039/C3CE42626B
3. P. Warrier, C.A. Koh, "Silicon clathrates for lithium ion batteries: A perspective," Applied Physics Reviews. 3, 040805 (2016). http://dx.doi.org/10.1063/1.4958711
4. L. Krishna and C. A. Koh, “Inorganic and methane clathrates: Versatility of guest–host compounds for energy harvesting,” MRS Energy & Sustainability, vol. 2, p. E8, 2015. https://doi.org/10.1557/mre.2015.9
Primary Contacts:
Prof. Carolyn Koh, Chemical and Biological Engineering, ckoh@mines.edu
Prof. Reuben Collins, Physics, rtcollin@mines.edu
Student Preparation
Qualifications
A general familiarity with the concept of crystal structure would be useful. The ability to work with and plot experimental data files would be helpful. A very basic understanding of the concepts of energy, waves and light would be useful. But mostly an interest in learning to use new techniques, in experiencing the research process, and an excitement at learning new things is probably the critical need. Much of the specific knowledge required for the project will be provided by the mentors who have a great deal of experience working with undergraduates on meaningful research.
TIME COMMITMENT (HRS/WK)
4-5
SKILLS/TECHNIQUES GAINED
The student will perform rapid thermal annealing to convert amorphous phases to crystalline phases, chemical etching to remove impurity phases, and thin film lift off to expose new film surfaces. The student will characterize these treatments using X-ray diffraction, Raman scattering, and Electron Paramagnetic Resonance.
MENTORING PLAN
The student will participate in weekly group meetings of the clathrate team. This is a collegial environment where the student can present their results along with grad students and faculty and also get advice on how to prepare visual aids, graphs, etc. that successfully convey their activities. They will interact with faculty, research faculty, and grad students as needed to obtain training and advice on experimental and analysis techniques. They will meet monthly with their mentors for advice that is more oriented toward career than specific research groups. Many of these meetings, such as the group meetings and monthly meetings, are presently run remotely. We have been successful and doing training both remotely and in person following careful social distancing rules. The group is concerned about spread of COVID-19 and has procedures in place to allow work to proceed while minimizing infection risk.
PREFERRED STUDENT STATUS
Freshman
Sophomore
Junior
Senior