Frequency Response of Gold Impurity Centers in the Depletion Layer of Reverse-Biased Silicon p+n Junctions

Abstract

The frequency dependence of ΔV/Δ(C_rf⁻²), which is closely related to the space‐charge density of a reverse‐biased p⁺n junction containing deep impurities, is discussed by using Goodman's model. In order to measure the variation of ΔV/Δ(C_rf⁻²) with frequency, a special technique has been developed. The experimental result on a gold‐doped silicon p⁺n junction shows that frequency dispersion of gold acceptors is well explained by assuming a single deep level, whose charging and discharging time constant is 8.0 × 10⁻⁴ sec at room temperature. A value of 1.25 × 10³ sec⁻¹ is obtained for the thermal emission rate of electrons from the gold acceptors, which agrees well with the data obtained from the photo and dark junction current and capacitance experiments. This result differs from that determined by capture rate measurements. The disagreement is removed by taking into account an electron capture process through the excited states of the gold acceptors under non‐equilibrium conditions.