Use of low-frequency capacitance in deep level transient spectroscopy measurements to reduce series resistance effects

Abstract

In this article, we demonstrate the usefulness of a low-frequency capacitance deep level transient spectroscopy (LFDLTS) technique suitable for samples with a large built-in resistance in series with the depletion capacitance. As a case study, we investigate the effects of series resistance arising from the contact resistance and the bulk resistance of aluminum gallium arsenide epitaxial layers grown on semi-insulating gallium arsenide substrates. We show that there can be significant errors in the density and the activation energy of the traps (the so-called DX centers) determined by the conventional high-frequency (1 MHz) capacitance deep level transient spectroscopy measurements when the series resistance associated with the sample is high. On the other hand, the LFDLTS measurements are found to be free from these artifacts related to the series resistance effects.