  Amplification of the photocurrent in heterostructures of silicon dioxide
films containing cobalt nanoparticles grown on gallium arsenide SiO2(Co)/GaAs
has been observed in magnetic field in the avalanche regime. While the
avalanche process is suppressed by the magnetic field and the current
decreases, for photon energy E greater than the GaAs bandgap energy the
photocurrent significantly increases. The amplification reaches 9.5 for E =
1.50 eV. The effect of the photocurrent amplification is explained by the
spin-dependent recombination process at deep impurity centers in GaAs.
