1.26 mu m intersubband transitions in In0.3Ga0.7As/AlAs quantum wells

We observed room-temperature intersubband transitions at 1.26 mum in n-dope d type-II In0.3Ga0.7As/AlAs strained quantum wells. An improved tight-bindi ng model was used to optimize the structure parameters in order to obtain t he shortest wavelength intersubband transition ever achieved in a semicondu ctor system. The corresponding transitions occur between the first confined electronic levels of the well following mid-infrared optical pumping of el ectrons from the barrier X-valley into the well ground state. (C) 2000 Amer ican Institute of Physics. [S0003-6951(00)02950-8].