Electronically controlled motion of hydrogen in silicon

We report on the quantitative study of charge-state-dependent local motion of hydrogen around carbon in Si, which was directly probed by measuring the recovery of stress-induced alignment of a hydrogen-carbon complex by means of deep-level transient spectroscopy under uniaxial stress. We have found that hydrogen jumps from a bond-centered site between C and Si atoms to another with an activation energy of 1.33 eV and a frequency factor of 7.1 × 10¹⁴ s^-1 in the electron-empty charge state while hydrogen jumps much faster in the electron-occupied charge state with a lower activation energy of 0.55 eV and a smaller frequency factor of 3.3 × 10⁶ s^-1. We have concluded that the hydrogen-carbon complex captures an electron from the conduction band at its gap state with antibonding character, lowering the barrier and frequency factor for hydrogen motion in the electron-occupied charge state.