Features of the long-term photo EMF relaxation in a heteroepitaxial ZnSe-GaAs structure

The spectral characteristics and transverse distribution of the photo emf w ere studied in a heteroepitaxial ZnSe-GaAs structure obtained by MBE on a z inc-stabilized GaAs(100) substrate surface. The spectral measurements revea led unusual manifestations of the long-term photo emf relaxation, whereby t he amplitude of the spectral characteristic of the photo emf depends on the direction of wavelength variation of the exciting monochromatic light. Dep endence of the amplitude and sign (phase) of the photo emf on the intensity of light absorbed in the sample can be explained by time variation of the effective lifetime of the electron-hole pairs and by a difference in the li fetime values between various layers of the structure. Resistivity gradient s at the heterostructure interface exhibit a layer character. (C) 2000 MAIK "Nauka / Interperiodica".