Electronic structure of amorphous Si measured by (e,2e) spectroscopy

Abstract

Energy-resolved electron momentum densities are determined for a thin Si film evaporated onto a carbon foil. This is done by transmission (e,2e) spectroscopy, a technique that does not rely on crystal momentum and is therefore ideally suited for the study of amorphous materials. Spectra were collected with an energy resolution of 2 eV and a momentum resolution of 0.15 au (0.3 AA-1). The main feature disperses in a strikingly similar way to the crystalline ones. In addition to the dispersion the intensities of the peaks are obtained. In spite of having only a qualitative understanding of the shape of the spectra, the results of the comparison of measured amorphous momentum densities with calculated crystalline ones are reasonable. The basis of this agreement between amorphous solid and crystalline theory is discussed.

Electronic-structure investigation of oxidized aluminum films with electron-momentum spectroscopy

“…1 This was demonstrated by a series of (e,2e) experiments on solid targets [2][3][4][5][6][7][8][9][10] in the last few years. In these experiments, the (e,2e) spectrometer 11 of The Flinders University of South Australia was used.…”

“…12͔͒ and significantly improved both energy and momentum resolution. In addition to the energy-resolved momentum distribution of electrons in valence bands 5,[8][9][10] and core levels, 4,9 which can be uniquely measured by EMS, information has also been obtained on the influence of lattice order on the electronic structure, 6 the electronic structure of adsorbates, 7,9 and the annealing effects on the electronic structure of the surface. 3 The targets used in these investigations include carbon ͑amorphous carbon, graphite, highly oriented pyrolitic graphite, and diamondlike amorphous carbon͒, semiconductors ͑amorphous silicon and amorphous germanium͒, and a semiconductor compound ͑polycrystalline silicon carbide͒.…”

Observing electron motion in solids

“…Measurements of various stages of recrystallization of amorphous carbon films were made by . Amorphous silicon was studied by Vos, Storer, et al (1995a) and SiC by Cai et al (1995b). Finally oxygen adsorbed on amorphous carbon was studied by Vos, Canney, et al (1995b).…”

Electron momentum spectroscopy of solid surfaces

“…band of an amorphous carbon target with increasing annealing (Vos et al 1994). The density is given by a linear grey scale.…”