Persistent photoconductivity in InGaP/GaAs heterostructures

Photoconductivity spectra have been investigated in InGaP/GaAs heterostruct ures, and persistent photoconductivity (PPC) has been observed. Through a d etailed study of the dependence on excitation wavelengths and the decay kin etics, we identify that the separation of electrons and holes due to the ma croscopic potential barrier between the heterointerface and the substrate i s the origin of the PPC effect. In addition, we found that the PPC effect c an be reduced and the photosensitivity can be enhanced after hydrogenation. We suggest that this behavior can be interpreted by the fact that the inco rporation of atomic hydrogen produces donor neutralization and passivates t he activity of defective bonds, thus reducing the potential barrier for the recombination of electrons and holes and enhances the photoresponse. (C) 1 999 American Institute of Physics. [S0003-6951(99)05645-4].