Terahertz generation in $a$-Si:H/$c$-Si geterostructures under excitation by femtosecond laser pulses

The results of a study of the generation of terahertz (THz) radiation in $p$–$n$ heterostructures based on $a$-Si:H/$c$-Si under their photoexcitation by femtosecond laser radiation with wavelengths of 400 and 800 nm are presented. An increase in the differential efficiency of THz generation by several times was observed when switching from long-wave to short-wave pumping. A broadening of the amplitude spectrum of THz radiation and an increase in its upper limit frequency (at a level of 0.01 from the maximum) to values of about 2.7 THz are also observed.