Determination of semiconductor quasi-Fermi level separation under illumination

Two new experimental techniques are described for the determination of the quasi-Fermi level separation in a semiconductor material, exposed to illumination. In one method, this separation is obtained from the change in the value of the measured high frequency capacitance of a transparent conductor-oxide-silicon structure in strong inversion, with the intensity of optical illumination. In the other method, the quasi-Fermi level separation is obtained from the shift of the experimentally obtained low frequency space-charge capacitance versus the surface potential curve in strong inversion. Results obtained from the two techniques agreed well.