Direct Evidence of Divacancy Formation in Silicon by Ion Implantation

Abstract

The production of divacancies in Si by 400-keV oxygen ion implantation (ΦI = 1.75 × 1014 cm−2, two sides) was detected by the characteristic divacancy optical absorption band at 1.8 μ. This band has been previously correlated with the presence of divacancies in electron- and neutron-irradiated silicon. Ion-produced divacancy annealing near 200°C was observed to correlate with neutron-produced divacancy annealing. Detailed comparisons of the annealing of electron-, neutron-, and ion-produced divacancies suggest that the ion-produced divacancies anneal primarily in regions with sink concentrations ≥ 1019 cm−3.

Role of structural disorder in optical absorption in silicon

“…1 along with c-Si as a reference for comparison. While an optical signature was anticipated based on the results of Stein et al 13 for clusters with dangling bonds ͑V 1 and V 2 ͒, the substantial magnitude and bandwidth of optical absorption enhancement over c-Si was unexpected. The unsaturated bonds in V 1 and V 2 correspond to typical defect FIG.…”

“…25,26 The effects of Si divacancies ͑dangling bonds͒ on optical absorption were previously measured with spectrophotometry by Stein et al 13 and Knief and von Niessen 12 modeled the effect of both vacancy concentration and coordination defects on optical absorption. Based on these previous results, we were motivated to determine if optical signatures would be readily observable for FC vacancy clusters despite their expected transparency to common experimental characterization techniques.…”

“…Significant effort is required to improve c-Si absorption through techniques including transition metal doping to create intermediate bands 9 and growth of Si nanowire arrays that function as broadband absorption layers. 10 It is well established that variations in phase, 2,11 defect-content, 12,13 and morphology [14][15][16][17] ͑porous Si morphologies vary greatly͒ of Si produce appreciable changes in the absorption spectra. Knief and von Niessen 12 succinctly classified the absorption spectra of a-Si materials into three categories: ͑1͒ high-energy absorption ͑like c-Si͒ in which transitions occur between extended electronic states ͑bands͒; ͑2͒ Urbach absorption at lower photon energies in which optical transitions occur between localized states in one band ͑valence or conduction͒ and extended states in the opposite band; and ͑3͒ tail or defect absorption at the lowest photon energies in which optical transitions are assisted by localized states near the Fermi energy.…”

Doping and processing epitaxial GexSi1−x films on Si(100) by ion implantation for Si-based heterojunction devices applications

“…Data obtained from Ref. 82,90 Similar defect-removal mechanisms might be applicable for GeSi as well. 4 (open symbols, dotted line).…”

First-Principles Prediction of Optical Absorption Enhancement for Si Native Defect Clusters under Biaxial Strain

“…6 Optical methods 1 provide a non-destructive means of semiconductor characterization because optical properties are derived from electronic structure. Variations in phase 3 and defect-content 7,8 of Si produce significant changes in the optical absorption spectra, which suggests the plausibility of defect engineering 9 the spectra through structural manipulation. While c-Si absorption 10 is negligible below the 1.11 eV experimental bandgap, 11 Si absorption at lower energies is attainable through the participation of band tail extended states ͑Urbach region͒ or at even lower energies in the presence of localized defects, such as native defect clusters, that can generate states near the Fermi level.…”