Photoreflectance study of indium segregation in the InGaAs quantum well

The electron-hole states in the molecular beam epitaxy grown GaAs/In0.5Ga0.5As quantum well, placed into space charge region, have been studied by photoreflectance spectroscopy. The energies of electrons and holes have been calculated in the envelope function model including deformation-induced changes in the band structure of quantum well. It is shown that the best accordance between experimental and theoretical data is achieved in the case of band offset Q = ;Ec/;Ev = 0.62/0.38 at GaAs/In0.5Ga0.5As heterojunction. The most intense transition is observed in this case between 1 electron and 1 light hole energy. This fact is connected with the indium segregation in the GaAs/In0.5Ga0.5Asquantum well. In this case one could obtain the flat bands in the quantum well and realize the parity selection rules for the rectangular potential. The model of the nonsymmetrical rectangular potential is applied to describe the energies of electronic levels in the quantum well. The segregation parameters have been calculated from the segregation-induced shift of the energies of interband transitions in the GaAs/In0.5Ga0.5As quantum well.