Capacitance of Junctions on Gold-Doped Silicon

Abstract

The capacitance of p+—n junctions and Schottky barriers on gold-doped, n-type silicon has been measured as a function of applied bias and time in the temperature range 205°-255°K. The gold-diffusion temperature was 1000°C. The time dependence of the capacitance has been examined on the basis of a model which assumes that the gold acceptor level has the same charge as in the bulk for some distance λ(t) from the edge of the depletion region. The analysis yields a value for the density of neutral acceptors in the depletion region of 1.1×1016 cm-3, indicating that en»ep for the gold center. The energy associated with the capacitance time constant is 0.545±0.005 eV and the capture cross section σn is calculated to be 2.9×10-15 cm2 at 250°K. Of a more general nature, a simple procedure is described for determining the contribution of slow-responding deep levels to the capacitance of abrupt p—n junctions. This involves a plot of dV/d(1/C2) vs C, a relationship which was essentially derived by Goodman.