Vacancies and the Chemical Trapping of Hydrogen in Silicon

The first evidence for Si${\mathrm{H}}_1$-like centers in crystalline Si ($c$-Si) is presented from infrared measurements of H (D) implanted at 80 K. In contrast to Si${\mathrm{H}}_1$ centers in amorphous Si ($a$-Si) which are stable to ≈ 700 K, the crystalline band anneals below 300 K with an activation energy and illumination enhancement that are characteristic of the Si vacancy. These results relate specific defects for implanted H in $c$-Si to previous observations for H in $a$-Si.