Identification of donor deactivation centers in heavily As-doped Si using time-of-flight medium-energy ion scattering spectroscopy

Electrically-inactive arsenic (As) complexes in silicon are investigated using time-of-flight medium-energy ion scattering spectroscopy. In heavily As-doped Si, the As atoms that are segregated in the Si interface region just below the SiO₂ are found to be in interstitial forms (As_i), while the As atoms in the bulk Si region are found to be in the substitutional form (As_Si). Despite the substitutional form of As, most of the As are found to be electrically inactive in the bulk region, and we identify the As to be in the form of a 〈111〉-oriented As_Si-Si-vacancy (As_Si-V_Si) complex. The As_i atoms in the interface Si region are found to exist together with Si-interstitial atoms (Si_i), suggesting that the As_i atoms in the interface Si region accompany the Si_i atoms.