Electronic Structure of Ordered Ga0.5In0.5P/GaAs Heterointerface Studied by Raman-Scattering and Photoluminescence-Excitation Measurements

We have investigated the electronic band structure of a long-range-ordered Ga0.5In0.5P/GaAs heterointerface by optical measurements and a semi-empirical calculation. Raman-scattering spectra of the ordered Ga0.5In0.5P/GaAs samples show plasmon–phonon coupled modes induced by dense electron accumulation at the heterointerface, in contrast to that of the unordered sample which shows the spectrum of bulk GaAs. Furthermore, the Franz–Keldysh oscillation observed in the photoluminescence-excitation spectrum indicates a strong interface electric field. According to the results of a comparison between the experiment and a semi-empirical calculation based on Poisson's law, it is found that the spatial distribution of the accumulated electron density is modified strongly by the conduction-band discontinuity and the interface field, depending on the order parameter.