Photoelectronic properties of high-resistivity GaAs : O

Abstract

The photoelectronic properties of high-resistivity n-type GaAs : O have been investigated through measurements of dark conductivity and Hall effect, optical absorption, photoconductivity, and photo-Hall effect as a function of photon energy, light intensity and temperature, optical quenching of photoconductivity, and thermally stimulated conductivity. The results of all measurements can be described consistently by a four-level model (0.5, 0.7, 1.0, and 1.25 eV below the conduction band edge) plus eight electron trapping states (with depth between 0.15 and 0.54 eV) common to many different types of high-resistivity GaAs. At 82 °K, illumination with photons of energy between 1.0 and 1.25 eV produces a major shift in the photoconductivity toward p type and a persistent quenching of n-type photoconductivity that recovers abruptly only upon warming above 105 °K. Low-frequency photocurrent oscillations are associated with the 1.25-eV level. The capture cross section of five of the electron trapping states is small [(5–8) ×10−19 cm2)] and decreases with electric field.