Terahertz Frequency Materials Testing at Cryogenic Temperatures and in High Magnetic Fields

ABSTRACT: Terahertz (THz) spectroscopies offer unmatched non-contact probing of low-energy excitations underlying electronic transport and magnetism in a wide range of novel materials. To-date, expensive and complex THz Time Domain Spectroscopy (THz-TDS) systems are the most common THz source used in these studies. Lower cost, continuous wave (CW-THz) spectroscopy systems can offer comparable performance as THz-TDS but with superior spectral resolution. Lake Shore will leverage its existing efforts in coherent CW terahertz emission and detection at cryogenic temperatures to deliver a prototype CW-THz materials characterization platform tailored to the research needs of the AFRL materials community. In Phase I, Lake Shore will collaborate with Wright State University and the University of Arizona to develop and validate material parameter extraction methodologies with CW-THz spectroscopy in cryogenic and high magnetic field environments. Comparisons between Hall, THz-TDS, and CW-THz measurements on known semiconductor and novel materials of interest to AFRL researchers will provide a benchmark and methodology for CW-THz materials characterization. A final report at the end of Phase I will discuss these efforts and outline necessary alterations to the hardware platform and measurement methodologies required for materials of interest as well as additions to CW-THz material parameter extraction algorithms. BENEFIT: Lake Shore"s vision is to provide researchers of novel semiconductor and magnetic materials with a turnkey characterization solution that is affordable, highly capable and readily usable. Affordability is achieved in part over previously complex and costly time-domain systems (THz-TDS) by utilizing emerging, lower cost CW-THz generation and detection. Other benefits include faster examination of novel materials due to non-destructive, non-contact THz characterization; more convenient, higher resolution measurements due to CW-THz over THz-TDS; and new research insights into material properties that will help accelerate the development of the next generation of electronic devices. The viability of using CW-THz for these types of characterizations will be demonstrated in this Phase I project.