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Title: Hydrogen passivation of titanium impurities in silicon: Effect of doping conditions

While the contamination of solar silicon by fast diffusing transition metals can be now limited through gettering, much attention has been drawn to the slow diffusing species, especially the early 3d and 4d elements. To some extent, hydrogen passivation has been successful in healing many deep centers, including transition metals in Si. Recent deep-level transient spectroscopy (DLTS) measurements concerning hydrogen passivation of Ti revealed the existence of at least four electrical levels related to Ti{sub i}H{sub n} in the upper-half of the gap. These findings challenge the existing models regarding both the current level assignment as well as the structure/species involved in the defects. We revisit this problem by means of density functional calculations and find that progressive hydrogenation of interstitial Ti is thermodynamically stable in intrinsic and n-doped Si. Full passivation may not be possible to attain in p-type Si as Ti{sub i}H{sub 3} and Ti{sub i}H{sub 4} are metastable against dissociation and release of bond-centered protons. All DLTS electron traps are assigned, namely, E40′ to Ti{sub i}H(-/0), E170′ to Ti{sub i}H{sub 3}(0/+), E(270) to Ti{sub i}H{sub 2}(0/+), and E170 to Ti{sub i}H(0/+) transitions. Ti{sub i}H{sub 4} is confirmed to be electrically inert.
Authors:
; ;  [1] ;  [2] ;  [3]
  1. Department of Physics and I3N, University of Aveiro, Campus Santiago, 3810-193 Aveiro (Portugal)
  2. Department of Chemistry, University of Surrey, Guildford GU2 7XH (United Kingdom)
  3. School of Electrical, Electronic and Computer Engineering, Newcastle University, Newcastle Upon Tyne NE1 7RU (United Kingdom)
Publication Date:
OSTI Identifier:
22311144
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 105; Journal Issue: 3; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ACTIVATION ENERGY; ALLOCATIONS; CRYSTAL DEFECTS; CURRENTS; DEEP LEVEL TRANSIENT SPECTROSCOPY; DENSITY FUNCTIONAL METHOD; DIFFUSION; DISSOCIATION; DOPED MATERIALS; HYDROGEN; HYDROGENATION; IMPURITIES; PASSIVATION; SILICON; TITANIUM; TRANSITION ELEMENTS; TRAPS