Diffusivity of the double negatively charged mono-vacancy in silicon. (10th April 2017)

• Record Type: Journal Article
• Authors: Bhoodoo, Chidanand; Vines, Lasse; Monakhov, Edouard; Gunnar Svensson, Bengt
• Is Part Of: Journal of physics. Volume 29:Number 20(2017)
• Publication Date: 2017-04-10
• Subjects: mono-vacancy -- silicon -- thermal migration -- DLTS -- ion implantation -- diffusivity; Condensed matter -- Periodicals; Matière condensée -- Périodiques; Vaste stoffen; Vloeistoffen; Natuurkunde; Electronic journals; Computer network resources; 530.4105
• DOI: 10.1088/1361-648X/aa693f
• Languages: English
• ISSNs: 0953-8984

Abstract

Abstract: Lightly-doped silicon (Si) samples of n -type conductivity have been irradiated with 2.0 MeV H + ions at a temperature of 30 K and characterized in situ by deep level transient spectroscopy (DLTS) measurements using an on-line setup. Migration of the Si mono-vacancy in its double negative charge state ( V 2− ) starts to occur at temperatures above ∼70 K and is monitored via trapping of V 2− by interstitial oxygen impurity atoms ( O i ), leading to the growth of the prominent vacancy-oxygen ( V O ) center. The V O center gives rise to an acceptor level located at ∼0.17 eV below the conduction band edge ( E c ) and is readily detected by DLTS measurements. Post-irradiation isothermal anneals at temperatures in the range of 70 to 90 K reveal first-order kinetics for the reaction V 2 − + O i → V O ( + 2 e − ) in both Czochralski-grown and Float-zone samples subjected to low fluences of H + ions, i.e. the irradiation-induced V concentration is dilute ( ⩽ 10 13 cm −3 ). On the basis of these kinetics data and the content of O i, the diffusivity of V 2− can be determined quantitatively and is found to exhibit an activation energy for migration of ∼0.18 eV with a pre-exponential factor of ∼ 4 × 10 − 3 cm 2 s −1 . The latter value evidences a simple jump process without any entropy effects for the motion of V 2− . No deep level in the bandgap to be associated with V 2− is observed but the results suggest that the level is situated deeper than ∼0.19 eV below E c, corroborating results reported previously in the literature.