Electronic structure of amorphousSiOx:H alloy films studied by x-ray emission spectroscopy: SiK, SiL, and OKemission bands

Abstract

We present x-ray Si K, Si L, and 0 I( emission bands of hydrogenated amorphous SiO"alloy films covering the concentration range 0 & x~2.2. All spectral features in the emission bands were identified and attributed to Si 3s, Si 3p, and 0 2s, 2p derived states. With increasing x, the shape and the energy position of the main features of the Si E and Si L emission bands change significantly, particularly in the concentration interval 0.5 &x &1.5. A comparison with available ultraviolet (UPS) and x-ray (XPS) photoemission spectra demonstrates that x-ray emission bands for a-SiO are more sensitive to sample composition than UPS and/or XPS spectra. The random-bonding model and the random-mixture model of the structure of SiO"alloys are discussed in view of the x-ray emission spectra. For x =2, the Si X, Si L, and 0 K spectra are very similar to those observed for cx-quartz (c-Si02). This justifies interpretation of all features of a-Si02:H on the basis of c-SiO&. We therefore performed self-consistent pseudopotential calculations of the total density of states and the local partial density of states of Si 3s, Si 3p, Si 3d, 0 2s, and 0 2p of cr-quartz. The calculations confirm that due to the high electronegativity of oxygen nonbonding, Si 3d-like states are created which, for high values of x, clearly show up in the Si L emission bands. Finally, we discuss the long-standing so-called d-orbital controversy about Si02 and give an explanation of it.

X-ray fluorescence study of organic-inorganic polymer conversion into ceramics induced by ion irradiation

“…1͒ shows a two-peaked structure similar to SiO 2 . 27 This is expected because the silicon atoms in a siloxane threedimensional gel are coordinated by two oxygen and one hydroxide side groups via oxygen atoms, and therefore one would expect a dominant silicon-oxygen bonding emission spectrum. Figure 3 and Tables I-III present a comparison of the experimental and calculated XPS valence band ͑VB͒ and XES spectra of PTES.…”

“…Therefore we have observed the same calculation problems with our Si L II,III XES that have been observed in other silicon-oxygen systems. 27 …”

“…Also, we did not measure the intensity distribution in the region from 70-82 eV, where an additional sub-band related to silicon 3s-oxygen 2s bonding is seen in the spectra of SiO x . 27 According to reference, 27 the experimental and theoretical silicon L II,III XES of the siliconoxygen system contains three sub-bands that are related to silicon 3s-oxygen 2s, silicon 3s-oxygen 2p, and silicon 3d-oxygen 2p bonding, respectively. We only observe two main sub-bands in our calculated PTES spectrum.…”

Impact of solid-phase crystallization of amorphous silicon on the chemical structure of the buried Si/ZnO thin film solar cell interface

“…of ZnO detected in second order͒. [5][6][7] The effective attenuation lengths ͑ ‫ء‬ ͒ for the Si L 2,3 and O K emission roughly correspond to 0.5 and four times the Si layer thickness, respectively. 8 Hence, the Si L 2,3 spectra are dominated by the near-surface material properties of the Si layer and the O K measurements primarily probe the chemical structure of the TCO bulk.…”

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

“…Analysis of obtained data shows that the surface layer of original por-Si mainly involves crystalline, amorphous and rather strongly disordered silicon, represented by the reference phases c-Si, a-Si, Si:Ar and low-coordinated silicon as well as the oxides SiO 1.3 , SiO 1.7 и SiO 2 [20]. During deposition of metals into porous silicon iron and cobalt interact in a different way with porous silicon.…”