Molecular structure of porous Si

Abstract

Nanocrystalline Si particles of 10 nm size, doped with traces (1 at. %) of Sn, are prepared by mechanical attrition in an inert ambient. After stain-etching, the particles photoluminesce at room temperature. 119Sn Mössbauer spectroscopy, Raman scattering, photoluminesce, and Fourier transform infrared spectroscopy measurements performed as a function of stain-etching time reveal systematic changes, and suggest that the molecular structure of porous Si consists of nanocrystalline Si particles with surfaces passivated by H and/or O atoms.

Silicon Nanocrystals: Photosensitizers for Oxygen Molecules

“…Figure 2 shows typical transmission electron microscopy (TEM) images of nanoporous Si. Electrochemical or stain etching of p-doped bulk Si wafers [36,37] results in a sponge-like structure that consists of Si nanocrystals of different sizes. [38] They are typically a few nanometers wide, as can be seen in Figure 2a, and retain the diamond lattice structure of bulk Si (Fig.…”

“…2b, the lattice fringes correspond to (111) planes of Si nanocrystals). [37] As a result, PSi is characterized by a very large internal surface area. [39] Hydrogen atoms passivate the internal surface of as-prepared materials, which reduces the number of non-radiative surface defects such as dangling Si bonds.…”

Porous Silicon Formation by Stain Etching

“…In particular, the iodate ion IO 3 À produces extremely high etch rates when ethanol is added to the etchant to avoid the precipitation of I 2 . However, the halogens are able to react thermally with Shih et al (1992Shih et al ( , 1993, McCord et al (1992), Kidder et al (1992), Dubbelday et al (1993), Steckl et al (1994, Chandler-Henderson et al (1994), Liu et al (1994, 2007, Kalem and Rosenbauer (1995), Anaple et al (1995), Amato (1995), Schoisswohl et al (1995), Jones et al (1995), , Di Francia and Citarella (1995), Winton et al (1996Winton et al ( , 1997 Kolasinski and Gogola (2012) Si and do so in a manner that destroys por-Si films. On the other hand, Xu and Adachi (Xu and Adachi 2006) investigated etching in KIO 3 + HF solutions.…”

“…By far the most commonly used oxidant is HNO 3 , either to etch Si uniformly (Yamamura and Mitani 2008;Robbins and Schwartz 1959Schwartz and Robbins 1976;Jenkins 1977;Kooij et al 1999;Kulkarni and Erk 2000;Svetovoy et al 2006) or to form por-Si (Turner 1960;Archer 1960;Beckmann 1965;Beale et al 1986;Shih et al 1992Shih et al , 1993McCord et al 1992;Kidder et al 1992;Dubbelday et al 1993;Steckl et al 1994;Chandler-Henderson et al 1994;Liu et al 1994Liu et al , 2007Kalem and Rosenbauer 1995;Anaple et al 1995;Amato 1995;Schoisswohl et al 1995;Jones et al 1995;Di Francia and Citarella 1995;Winton et al 1996Winton et al , 1997Velasco 2003;GuerreroLemus et al 2003;González-Díaz et al 2006;Zeng et al 2005;Melnichenko et al 2005;Luchenko et al 2007;Balaguer and Matveeva 2010;Mogoda et al 2011;Lippold et al 2011Lippold et al , 2012Terheiden et al 2011). Other sources of nitrogen oxo ions such as NaNO 2 (Archer 1960;Melnikov et al 2008;Kelly et al 1994;…”

Confinamento de estados eletrônicos e vibracionais em microestruturas semicondutoras com progressiva redução da dimensionalidade

“…empregando várias técnicas de raios-X em nanoesferas muito pequenas ("'-' 20 Â) de Si oxidado e Si-por passivado com H sugerem que o thamaremos "infravermelha~ a PL com pico no infravermelho ou vermelho, e denominaremos ''visível" a PL com máximo de intensidade do verde ao azul. [Anaple 1995]. Cálculos tight-binding dependentes no tempo [Hilll995] praticamente confirmam a principal conclusão dos dóis grupos acima: O…”