On a scheme of nanoheterointerfacial intersubband 15-THz luminescence

A nanostructure is designed consisting of two (the front [F] and the back [B]) communicating asymmetric quantum wells (QWs), separated by a barrier, with two energy matchings; one between the two ground sublevels and the other between the first excited sublevel of the [F] QW and the second excited one of the [B] QW, respectively. The energy separation between the first excited and fundamental [B] QW sublevel is appropriately small. The nanoheterointerface is studied under the influence of incoming photons with energy commensurate to the intersubband difference for the [F] QW. In particular, conduction electrons, having been optically pumped within the [F] QW, tunnel resonantly into the [B] QW, wherein they get radiatively deexcited. They, then, reach non-radiatively the local fundamental sublevel, on account of the smallness of its energy deficit with respect to the first excited one. By virtue of a new resonant tunnelling, they, now, reenter the [F] QW and the cycle is rerun. A simulative application predicts LASER operability in the 15-THz range.