NATURE OF CHARGE TRAPS IN ANODE OXIDE-FILMS ON GAAS

The influence of exposure to a wet atmosphere and vacuum annealing eff ects on the electron and hole traps in an anode oxide of GaAs by using ''optical charge method'' have been studied. Charging of the sample s urface by illumination for photon energies of 1.0 to 5.4 eV was record ed from the change in the dark value of the contact potential differen ce (CPD) between the sample and a transparent nickel net electrode. Th e CPD was measured using a dynamic capacitor (Kelvin) method. From cor relation of the optical charging and mass spectrometry and electron sp in resonant method experimental data it has been found that the defect s which include arsenic vacancies are traps for the holes. On the othe r hand, the oxygen atoms localized on gallium vacancies in the anode o xide are responsible for the electron trapping.