An apparatus for spatially resolved, temperature dependent near infrared reflectance measurements for identifying thermochromic transitions in combinatorial thin film libraries
Sara C. Barron, Nam T. Nguyen, Nhan V. Nguyen, Martin L. Green, Mitul P. Patel
A metrology and data analysis protocol is described for high throughput construction of thermochromic metal-insulator phase diagrams for lightly substituted VO2 thin films. The technique exploits the abrupt change in near infrared optical properties, measured in reflection, as an indicator of the temperature- or impurity-driven metal-insulator transition. Transition metal impurities were introduced in a complementary combinatorial synthesis technique for producing thin film libraries with the general composition space V1-xMxO2, with M = one or more transition metals and x varying continuously across the library. The measurement apparatus acquires near infrared reflectance spectra at arbitrarily many library locations, each with a unique film composition, at temperatures of 1 °C to 85 °C. To maintain high throughput throughout, the measurement protocol is computer controlled to automate the collection of thousands of reflectance spectra, representing hundreds of film compositions at tens of temperatures. A straightforward analysis algorithm is implemented to reduce the thousands of spectra to knowledge such as thermochromic transition temperatures and regions of no thermochromic transition. The resulting impurity composition temperature phase diagrams will contribute to the understanding of metal-insulator transition in doped VO2 systems, and to the development of thermochromic smart windows.
, Nguyen, N.
, Nguyen, N.
, Green, M.
and Patel, M.
An apparatus for spatially resolved, temperature dependent near infrared reflectance measurements for identifying thermochromic transitions in combinatorial thin film libraries, Review of Scientific Instruments, [online], https://doi.org/10.1063/1.4935477
(Accessed December 7, 2023)