Intersubband radiation in weakly bound superlattice structures with wide quantum wells in a transverse electric field

Long-wavelength IR radiation was detected in a long-period superlattice with wide quantum wells under conditions of electrical injection of charge carriers into lower size-quantization subbands, which was explained by intersubband transitions. The detected radiation probably suggests that there is a strongly nonequilibrium carrier distribution in subbands, caused by the difference between scattering processes into lower subbands with and without involving optical phonons.