Interband-transitions in InxGa1-xAs/GaAs strained layer superlattices

Room‐temperature photoreflectance (PR) measurements have been used to investigate the optical transition energies in InxGa1−xAs/GaAs strained layer superlattice structures grown by molecular‐beam epitaxy (MBE). Sharp PR features indicating excellent optical quality of these MBE grown structures were observed. The transition energies were calculated and PR spectra fitted to the theoretical line shape expression. By observing the variation of Cl‐Lbl (where Cl is the first conduction subband in InGaAs layers and Lbl is the first light‐hole subband in the GaAs layers) type II superlattice transition, which cannot be observed with photoluminescence even at low temperatures, a conduction‐band discontinuity of 70% was obtained. Further, an important outcome of this study is the observation of strong PR features from the spatially indirect Cl‐Lbl transition which indicates that the modulation of band to band transitions can be a dominant PR line shape determining mechanism.

Published in:
Journal of Vacuum Science & Technology B, 7, 5, 1106-1110

 Record created 2007-08-31, last modified 2018-03-18

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