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Effects of O-2 diss...
Effects of O-2 dissociation on a porous platinum coating in the thermal oxidation of GaAs
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- Hultquist, Gunnar (författare)
- KTH,Korrosionslära
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Graham, M. J. (författare)
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Wee, A. T. S. (författare)
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Liu, R. (författare)
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Sproule, G. I. (författare)
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Dong, Q. (författare)
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Anghel, C. (författare)
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(creator_code:org_t)
- The Electrochemical Society, 2006
- 2006
- Engelska.
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Ingår i: Journal of the Electrochemical Society. - : The Electrochemical Society. - 0013-4651 .- 1945-7111. ; 153:2, s. G182-G186
- Relaterad länk:
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https://urn.kb.se/re...
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https://doi.org/10.1...
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Abstract
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- A 20-30-nm-thick porous Pt layer has been sputter-coated on a portion of a GaAs sample and subsequently the sample was oxidized at 500 degrees C in O-16(2) followed by O-18-enriched O-2. The oxide formed was characterized by Auger electron spectroscopy, secondary ion mass spectrometry, and X-ray photoelectron spectroscopy, all with a lateral resolution of about 100 mu m. Away from the Pt area, a mm-ranged gradually decreasing degree of As oxidation was observed in the outermost oxide layer. In the Pt area, Ga was preferentially oxidized at the oxide/substrate interface producing a five to seven times thicker oxide than in an area without the influence of Pt. A strongly enhanced dissociation rate of O-2 on Pt particles and a subsequent O spillover to adjacent oxide explain the experimental observations. The mm-ranged spillover is believed to take place via fast lateral surface diffusion and results in the observed variation of oxidized As at the gas/oxide interface. In the Pt area, a high concentration gradient of dissociated oxygen across the oxide layer supplies a high flux of dissociated oxygen to the GaAs substrate where Ga is preferentially oxidized. The results clearly demonstrate that both a surface reaction and solid-state diffusion influence the oxidation rate. A localized high effective oxygen (O) activity that spills over to a nearby oxide area is believed to be a general phenomenon that is operating in oxides where a dissociating element such as Pt is present at O-2/oxide interfaces.
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