Pressure dependence of oxygen-related defect levels in silicon

Abstract

The activation energies of thermal donors and of the A center in silicon, the oxygen vacancy complex, are measured as a function of hydrostatic pressure by Hall effect and by deep level transient spectroscopy. The A center is classified as a deep level because the strong pressure dependence of its activation energy indicates a short-range potential. In contrast, thermal donors are true shallow levels associated with a long-range coulomb potential because of the low pressure dependence of their activation energy. Based on these results, an atomic model for thermal donors is suggested, consistent with results of investigations concerning pressure dependence of energy levels, formation kinetics, IR absorption, electrical activity, and electron paramagnetic resonance.