Abstract Temperature-dependent increase of the terahertz (THz) electric field emitted from the surfaces of optically pumped narrow-gap semiconductors InAs, InSb, and Cd x Hg 1− x Te is presented. In the case of Cd 0.2 Hg 0.8 Te increase up to 15–17 times has been observed, when cooling the sample from the room temperature to close to liquid-helium temperatures, and THz emission from this material becomes comparable to that of p-InAs emitter. This effect was explained in terms of the increased photoexcited electron excess energy due to the positive temperature coefficient for energy bandgap of Cd x Hg 1− x Te, as well as by weaker surface field screening and carrier–carrier scattering. Temperature-dependent modification of the shape of THz pulses emitted from InSb surfaces has been observed and attributed to plasma oscillation of the cold electrons.
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