Neutron irradiation induced changes of the electrochemical properties of n-GaAs

Abstract

Thermal neutron irradiation produces spatially and energetically homogeneous distributed defects in n-GaAs. These defects act as majority charge carrier traps and scattering centres and as recombination sites for photogenerated charge carriers. This leads to a lowering of the charge carrier concentration and mobility and to a decrease in the maximum photocurrent. Additionally, the photocurrent onset potential is further shifted in the positive direction versus the flat band potential. Annealing of irradiated samples at temperatures below 600°C leads to defect annihilation and thus to restoration of the original electrochemical properties. Annealing at temperatures above 600°C results in an arsenic deficient surface with electronic defect states in the band gap in the near-surface region. Recombination at these defects appears to affect only the maximum photocurrent and not the photocurrent onset potential.