Enhancement of the activation energy in modulation-doped AlxGa1−x As/InyGa1−yAs/GaAs quantum wells due to an embedded deep step layer

Photoluminescence (PL) measurements on modulation-doped AlxGa1−xAs/InyGa1−yAs/GaAs single and step quantum wells were carried out to investigate the interband transitions and to determine the activation energies in InyGa1−yAs quantum wells. The activation energy of the electrons confined in the step quantum well, as obtained from the temperature-dependent PL spectra, was larger than that of the electrons confined in the single quantum well. The enhancement of the activation energy in the modulation-doped single quantum wells due to an embedded deep step layer originated from an increase in the energy difference between the ground electronic state and the AlxGa1−xAs conduction band edge in the InyGa1−yAs quantum well. These results indicate that the activation energy in modulation-doped AlxGa1−xAs/InyGa1−yAs/GaAs single quantum wells depends on the electronic structure.