Direct determination of the thermal capture cross-section of majority carriers at deep centers in silicon using thermally stimulated capacitance

Abstract

The thermal capture cross-section of majority carriers at deep centers is determined from capacitance measurements versus temperature by determining the time dependence of the net concentration of ionized recombination centers. An abrupt p +− n(or n + − p) junction containing a deep level of constant density N T < N D ( N D is the constant density of shallow donors in the n region) is reverse-biased with a high voltage; then the sample is cooled to a low temperature. Applying an adequately chosen sequence of pulses, the resulting variation of the net concentration of ionized deep centers is measured by means of the thermally stimulated capacitance technique. From the experimental results, one can readily extract the thermal capture rate of majority carriers at the deep centers. The accuracy of the measurements enables us to determine in addition the temperature dependence of the thermal capture cross-section. We measured the thermal capture of electrons at neutral gold centers in n-type silicon, in th range 80–205 K, and found: σ 0 n=1.24 × 10 −1 6 ( T/300) −(0.02 ± 0.03)cm 2