THz Emission from Mercury Cadmium Telluride Films Grown on Cadmium Zinc Telluride Substrates

We have observed THz emission from single- and double-layer HgCdTe (MCT) films epitaxially grown on CdZnTe substrates photoexcited by femtosecond laser pulses. The emitted THz radiation was electro-optically detected in reflection-mode at the 45° specular direction. There is a dramatic variation in the emitted signal level from the double-layer samples, whereas the signal level from the single-layer samples shows a relatively constant variation with composition and/or geometry. For the double-layer samples, the highest peak amplitude recorded is 1/5 of that of an InAs emitter, analogous to double that of a standard ZnTe emitter, and shows promise for further enhancement.