Ultra-High Mobility and Temperature-Dependent Carrier Dynamics in Narrow-Gap Hg_1-x Cd_x Te Films

Mercury cadmium telluride (MCT) is a well-established semiconductor alloy with a widely tunable band gap in the infrared. However, there have been no comprehensive studies on its ultrafast THz photoconductivity dynamics. We report on ultra-high carrier mobilities ($6 \times 10^{\mathbf{5}} \mathrm{cm}^{\mathrm{2}}$/Vs) and long lifetimes in long-wave infrared MCT films as measured by time-resolved terahertz spectroscopy (TRTS). A crossover to negative terahertz photoconductivity at higher frequencies is also observed. Our results suggest that TRTS could find industrial application as a non-contact probe of MCT films for infrared photodetectors and imaging arrays.