Thermal activation energy of the gold−acceptor level in silicon

Abstract

The thermal emission rates of electrons and holes at gold−acceptor levels in silicon have been measured in P+N junctions as a function of temperature using the dark−current transient method. From these measurements the linearly extrapolated absolute zero thermal activation energies of electrons (553 meV) and holes (641 meV) have been determined taking the temperature dependence of the hole capture rate into account. The latter has been determined by measuring the diffusion length at different temperatures. Using earlier optical results which showed that the energy distance of the gold−acceptor center from the conduction band is independent of temperature, the thermal activation energies of electrons and holes are calculated as a function of temperature. These results are to within a few meV in agreement with previously published optical data. Using the principle of detailed balance in thermal equilibrium, values of c^t_p=1×10⁻⁷ cm³/s, c^t_n=2×10⁻³ cm³/s, and g_A?3.2 are estimated for the capture rates and the degeneracy factor, respectively, at room temperature.