Persistent photoconductivity in InGaP/GaAs heterostructures

Photoconductivity spectra have been investigated in InGaP/GaAs heterostructures, and persistent photoconductivity (PPC) has been observed. Through a detailed study of the dependence on excitation wavelengths and the decay kinetics, we identify that the separation of electrons and holes due to the macroscopic potential barrier between the heterointerface and the substrate is the origin of the PPC effect. In addition, we found that the PPC effect can be reduced and the photosensitivity can be enhanced after hydrogenation. We suggest that this behavior can be interpreted by the fact that the incorporation of atomic hydrogen produces donor neutralization and passivates the activity of defective bonds, thus reducing the potential barrier for the recombination of electrons and holes and enhances the photoresponse. (C) 1999 American Institute of Physics. [S0003-6951(99)05645-4].