THz emission from (100)- and (111)A-oriented multiple pseudomorphic quantum wells $\{\mathrm{InGaAs/InAlAs}\}$

The effect of the built-in electric field on THz emission from the elastically strained superlattices $\{$In$_{0.53+\Delta x}$Ga$_{0.47-\Delta x}$As/In$_{0.52-\Delta x}$Al$_{0.48+\Delta x}$As$\}$ epitaxially grown on (100)- and (111)А-oriented InP substrate under fs-laser pump was studied. The value of $\Delta x$ and, hence, the magnitude of elastic stresses were varied within the set of samples. The “red” shift of the peak in the 77 K photoluminescence spectra confirms the presence of a built-in electric field in the (111)А-oriented heterostructures caused by the piezoelectric effect. (100)-oriented superlattices generate THz emission with close values of the THz field amplitude (the deviation is no more than 30% of the average value) regardless of elastic stresses, while in the series of (111)-oriented superlattices THz emission increases significantly (by 75–90%) for highly stressed samples.