Stress-induced changes of thermal donor formation in heat-treated Czochralski-grown silicon

Abstract

Formation processes of oxygen-related thermal donors in Czochralski-grown silicon annealed at T=450°C under high hydrostatic pressures at P⩾1GPa are studied by means of electrical and optical measurements. As for heat treatment of materials at atmospheric pressure, the formation of thermal double donors (TDDs) takes also place in Czochralski-grown silicon subjected to compressive stresses during heat treatment. However, their formation rate turned out to be much larger than that observed under normal conditions, even in carbon-rich materials. This strongly enhanced formation of thermal donors is believed to be due to increasing diffusivity of oxygen under pressures. In addition to the TDDs, other shallow and deep thermal donors are also making their appearance in silicon heat treated under high pressures.