Effect of built-in electric field on the temperature dependence of transition energy for InP/GaAs type-II superlattices

Built-in electric field in InP/GaAs type-II superlattice structures considerably modifies the temperature dependence of the ground state (GS) transition energy in photoreflectance measurements. For moderate electric fields, the temperature dependence of the GS transition energy follows the bandgap of the GaAs barrier layer, and it decreases at a faster rate than that of the GaAs material in the case of larger values of built-in electric field. The GS excitonic feature red shifts with quantum well thickness, confirming that it originates from the superlattice structure. Further, the variation of the broadening parameter with temperature is governed by the scattering of electrons with longitudinal optical phonons. (C) 2011 American Institute of Physics. [doi:10.1063/1.3671630]