  In the avalanche regime we observed the negative photoconductance of
heterostructures of silicon dioxide films containing cobalt nanoparticles grown
on gallium arsenide, SiO2(Co)/GaAs. Light irradiation with the photon energy
less than the bandgap energy of the GaAs creates holes trapped on defects
within the GaAs bandgap, suppresses the avalanche feedback and causes a
reduction of the current flowing in the SiO2(Co)/GaAs.
