Effect of e-h Pairs on the Stability of Bond-Center Hydrogen in Silicon

Hydrogen injected into silicon at low temperature resides in the bond-centered site, H$^{+}$[BC]. This is the most fundamental hydrogen related defect in many covalent semiconductors. Thermal annealing shows H$^{+}$[BC] stability up to 150K, and correlates with Si vacancy migration. We report the first observation of the decay of H$^{+}$[BC] due to e-h pairs induced by energetic ions. Thin single crystal silicon films containing H$^{+}$[BC] ($\sim $35$\mu $m) were fabricated to permit subsequent transmission of energetic protons, creating high e-h pair concentrations and minimal displacement damage. In-situ infrared studies revealed a 90{\%} reduction of H$^{+}$[BC] sites after a 1.8 MeV proton dose of 50$\mu $C/cm$^{2}$ at 80K. Recombination of e-h pairs at defect sites is known to cause vacancy diffusion providing another mechanism for loss of H$^{+}$[BC]. Our results show the effect of e-h pairs on H$^{+}$[BC] stability. We interpret this in terms of the e-h pair/vacancy interaction.