XPS, USXS and PLS investigations of porous silicon

Domashevskaya

et al. 2009

Nanoporous silicon layers were obtained on different types of single crystalline silicon substrates by standard electrochemical etching in HF solution. Investigations of electron structure, surface layers phase composition and photoluminescence evolution in nanoporous silicon during natural ageing for the time period for up to one year were performed with the use of the ultrasoft X‐ray emission spectroscopy (USXES), X‐ray absorption near‐edge structure (XANES) spectroscopy and photoluminescence. USXES and XANES spectra represent local partial density of states in valence and conduction band, correspondingly. The presence of the elementary silicon together with different silicon suboxides in surface layers is shown. Considerable differences in the kinetics of ageing can explain different photoluminescence properties of nanoporous silicon doped with P and Sb. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Section: Xanes Resultsmentioning

confidence: 99%

Evolution of nanoporous silicon phase composition and electron energy structure under natural ageing

Turishchev

Domashevskaya

et al. 2009

“…It is much less for the sample A. One should note that if silicon sample has a peak at ~ 95 eV, it corresponds to the presence of Si-O bonds [6]. Hence, the sample A is oxidized much less than the sample obtained by the routine technology (sample B).…”

Section: Introductionmentioning

confidence: 96%

“…The energy broadening for these spectra was less than 0.2 eV. The obtained X-ray emission spectra were processed with the use of specially elaborated computer program allowing to determine phase composition for the obtained por-Si layers with the account of the contribution into experimental spectra of the components that can be involved in the porous layer [5,6].…”

Section: Introductionmentioning

confidence: 99%

Electron structure of porous silicon obtained without the use of HF acid

Кашкаров

Nazarikov

et al. 2009

Reproducible technique for obtaining of porous silicon samples without the use of fluoric acid was elaborated. The main component for electrochemical etching of silicon is a concentrated aqueous solution of NH4F. The obtained samples are characterized by unusual pore morphology and the presence of corrugated “nanoribbons” of Si on the surface of porous layer. The density of occupied electron states in the samples determined by ultrasoft X‐ray emission spectroscopy shows practically complete absence of Si‐O bonds in the near‐surface layers of porous silicon (por‐Si). Analysis of the data of X‐ray absorption spectra and X‐ray photoelectron spectra demonstrates the presence of a great amount of Si‐O bonds just on the surface of the sample and an unusual abrupt decay in the absorption spectra near Si L2,3 edge of elementary silicon. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

“…Therefore, L 2,3 absorption spectra represent the distribution of s,d unoccupied states. According to [1,17], porous silicon is a complex multi-phase system and its composition varies along the depth of the porous layer as well as with the time (ageing effect). [18].…”

mentioning

confidence: 99%

“…This property proves to be very useful for the study of the electron structure of the complicated multi-phase substances. Analysis of the X-ray spectra of the investigated samples of the investigated samples has been carried out by comparison with those ones of the reference compounds [17,19]. Let us consider Si L 2,3 emission spectra of porous layers presented in Fig.…”

mentioning

confidence: 99%

Electron structure of iron and cobalt nanocomposites on the basis of porous silicon

Кашкаров

Agapov

et al. 2009

Morphology and phase composition of porous silicon with electrochemically deposited Fe and Co particles as well as the particles of their mixtures were investigated by scanning electron microscopy (SEM) and X‐ray emission and absorption spectroscopy. Iron was shown to cover the surface of porous silicon while cobalt penetrates inside the pores in the form of nanoparticles. Iron Iron is present in the form of the phase of Fe2O3 with an admixture of FeO and Fe3O4. Cobalt forming nanoparticles is involved as metallic Co and Co2O3. Under co‐deposition of these metals from solution of their salts mixture cobalt favored penetration of iron inside the pores. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)