Far infrared electroluminescence in cascade type-II heterostructures

Far infrared radiation from type-II heterostructures is observed. The samples used for the observations have the form of ten-period cascade structures, each period containing InAs and AlGaAsSb quantum wells separated by a variband barrier. The results of studying the vertical transport and the electroluminescence testify that the radiation is caused by transitions between the electron and hole states existing in the adjacent quantum wells.