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

Journal Article · Mon Jul 21 00:00:00 EDT 2014 · Applied Physics Letters

DOI:https://doi.org/10.1063/1.4891575· OSTI ID:22311144

Santos, P.; Torres, V. J. B. ^[1]; Rayson, M. J. ^[2]; Briddon, P. R. ^[3]

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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)

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.

• OSTI ID: 22311144
• Journal Information: Applied Physics Letters, Vol. 105, Issue 3; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0003-6951
• Country of Publication: United States
• Language: English

Related Subjects

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