Abnormal lattice location and electrical activation in chalcogen-hyperdoped Si

Hyperdoping has emerged as a promising method for designing semiconductors with unique physical properties. In general, these properties are primarily determined by the lattice location of the impurity atoms in the host material. In this contribution, the lattice location of implanted chalcogens in Si was experimentally determined by means of Rutherford backscattering/channeling (RBS/C). The implication on the electrical activation of chalcogens in Si will be discussed with respect to the Hall effect results. The obtained carrier concentration and the RBS angular scans across the <100> and <110> axis reveal that the electrically active/inactive concentration of Te correlates with the concentration of substitutional/interstitial site Te atoms. Surprisingly, contrary to the general belief, we find that the interstitial fraction decreases with increasing impurity concentration. This abnormal dependence of lattice location and electrical activation on impurity concentration suggests that the formation energy for the substitutional Te or Te-Te dimers in Si is lower than for the interstitial Te. This assumption is theoretically verified by the first-principles calculations.