Effect of high pressure annealing on electrical properties of nitrogen and germanium doped silicon

Abstract

The effect of annealing at 720–920K under enhanced pressure (up to 1.4GPa) in argon ambient on electrical properties of the surface layer of the Czochralski and Float zone grown nitrogen doped silicon (doping level 1×1014–5×1015cm−3) and Czochralski grown germanium doped silicon (doping level 7×1017cm−3) was investigated by electrical C–V, I–V and admittance methods. The decrease in electron concentration was observed in nitrogen doped Czochralski grown silicon annealed under normal pressure at 720K. The stress induced increase in electron concentration was observed in nitrogen doped Czochralski grown silicon independently on nitrogen doping level in the range 1×1014–5×1014cm−3. No dependence of electron concentration on hydrostatic pressure was observed in nitrogen doped Float zone silicon even for high doping level of 5×1015cm−3. Germanium doped silicon indicated the strongly enhanced creation of thermal donors if processed at 1.1GPa. The observed effects can be explained as a result of the oxygen–nitrogen complexes in nitrogen doped silicon and the pressure stimulated creation of thermal donors both in nitrogen and germanium doped silicon.