ELECTRON STATES OF LOCAL CENTERS IN N-TYPE GaAs:O.

A study was made of the kinetics and steady-state characteristics of the dark capacitance and photocapacitance of n-type gallium arsenide crystals doped with oxygen. The investigation was carried out in the temperature range 200 - 300 degree K at photon energies of 0. 40 - 1. 4 eV. The kinetics of the dark capacitance and photocapacitance obeyed two exponential laws, which could be explained by the existence of two independent local centers with a ground state in the middle of the band gap. The thermal and optical ionization energies were identical for both centers. It was found that one of the centers had an additional state near the valence band representing the excited state of holes. The photoionization cross sections and the thermal electron-capture cross sections were determined.