@inproceedings{0f8199e86b9e4b5e821ef57a4b48f2cb,
title = "Photo-oxidation of Ge nanocrystals: Kinetic measurements by in situ Raman spectroscopy",
abstract = "Ge nanocrystals are formed in silica by ion beam synthesis and are subsequently exposed by selective HF etching of the silica. Under ambient conditions, the exposed nanocrystals are stable after formation of a protective native oxide shell of no more than a few monolayers. However, under visible laser illumination at room temperature and in the presence of O2, the nanocrystals rapidly oxidize. The oxidation rate was monitored by measuring the Raman spectra of the Ge nanocrystals in-situ. The intensity ratio of the anti-Stokes to the Stokes line indicated that no significant laser-induced heating of illuminated nanocrystals occurs. Therefore, the oxidation reaction rate enhancement is due to a photo-chemical process. The oxidation rate varies nearly linearly with the logarithm of the laser intensity, and at constant laser intensity the rate increases with increasing photon energy. These kinetic measurements, along with the power dependencies, are described quantitatively by an electron active oxidation mechanism involving tunneling of optically excited electrons through the forming oxide skin and subsequent transport of oxygen ions to the Ge nanocrystal surface.",
author = "Sharp, {I. D.} and Q. Xu and Yuan, {C. W.} and Beeman, {J. W.} and Ager, {J. W.} and Chrzan, {D. C.} and Haller, {E. E.}",
year = "2007",
language = "English",
isbn = "1558999159",
series = "Materials Research Society Symposium Proceedings",
pages = "87--92",
booktitle = "Group IV Semiconductor Nanostructures-2006",
note = "2006 MRS Fall Meeting ; Conference date: 27-11-2006 Through 01-12-2006",
}