Saturation of impurity photoconductivity in n-GaAs with intense YAG laser light

We report the observation of saturation of impurity photoconductivity in semiconducting n-GaAs illuminated by a Q-switched Nd:YAG laser with light intensity up to 3.5 MW/cm2. From the saturation of conductivity we determined the concentration of defects to be ≈1016 cm−3. These form the well-known 1.2-eV absorption band and are presumably Ga vacancies. The curve of photoconductivity versus light intensity can be fitted with a simple model, which yields the electron recombination coefficient. The relation of the absorption band to nonlinear optical studies in GaAs at 1.06 μ is reviewed.