Acquisition of a Recirculating Helium Cooler for Research and Education
Abstract
Equipment: New Mexico State University, a Hispanic-serving land-grant institution in Las Cruces, NM, requests funds to acquire a recirculating helium cooler for low-temperature measurements of optical constants (complex refractive index) from 5 to 800 degrees Kelvin using spectroscopic ellipsometry from 190 to 2500 nm and using Fourier-transform infrared ellipsometry from 2 to 40 micrometer wavelength. Due to a national shortage of liquid helium, this cooler is required to make such cryogenic measurements affordable and sustainable. This instrument will be offered to other institutions (universities, government labs, and companies) across the US for measurement services. Research: (1) Precise knowledge of the optical constants of infrared materials is required for infrared communication, sensing, and detector applications, including operation in extreme temperature environments. Our goal is to develop a universal description of optical constants for infrared materials, including InSb, InAs, GaSb, Ge, GaAs, InP, GaP, etc, which can also be applied to semiconductor alloys such as those consisting of germanium and tin. (2) The infrared optical response is related to lattice vibrations, free carriers (doping or metallic), and electronic effects (narrow-gap semiconductors). Therefore, another point of focus will be correlated complex oxides with d- and f-electrons, especially the relationship between the lattice dynamics and phase transitions (for example antiferromagnetic to paramagnetic, or metal-to-insulator). (3) Measurements at long wavelengths and very low temperatures will provide information on the electronic structure of topological quantum materials, such as Weyl semimetals (e.g., gray tin). Instruction: Ellipsometry is a unique tool for teaching undergraduate students. Much of the research proposed here will involve undergraduate students. The PI has an excellent track record of engaging undergraduate students in research, leading to journal articles and conference presentations. The instrument will also support an instructional laboratory course in optical spectroscopy. STEM education and outreach: Our lab will be used for outreach in orientation programs, tours for K-12 students, and in departmental orientation for new students. Engagement of students will increase retention and graduation rates of underrepresented and high-risk students, enhancing the participation of natural-born US citizens in STEM jobs related to national security. A small woman-owned business has expressed interested in commercial use of the instrument.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Aug 02, 2022
- Source ID
- W911NF2210130
Entities
People
- Stefan Zollner
Organizations
- Army Contracting Command
- New Mexico State University
- Office of the Secretary of Defense