Bound-to-extended state absorption in quantum wells confined by delta-likebarriers

Within the framework of a simple envelope function and effective mass appro ximation, by including the spatial variation of effective mass and nonparab olicity effects, we have investigated the energy spectrum and intersubband optical absorption in a quantum well with additional thin and higher (delta -like) cladding barriers on either side of the well. The dependence of the absorption coefficient on the structure parameters, doping level, photon en ergy and temperature has been investigated. The absorption coefficient and spectrum strongly depend on the cladding barrier tunnel transparency. The p eak absorption wavelength is shifted towards the high energies as the barri er transparency decreases. The temperature shift of the absorption peak is very small. The results are compared with experiments of Schneider et al. [ 7, 8] taking into account the broadening induced by well width fluctuations . (C) 1999 Academic Press.