Electronic structure of solids measured by soft X-ray emission
The use of soft X-ray emission spectroscopy for studying valence band electronic gun, the grazing incidence spectrometer, and the electronics for the photodiode array detector, is described. Also discussed is the data processing and analysis involved in the experiment. Silicon and silicon nitride are studied using soft X-ray emission spectroscopy. The silicon L emission spectrum is compared to the spectrum calculated from a LCAO method using 3[sub 3] and 3p atomic states. In silicon nitride, the observed spectrum is compared to a density of states calculated with and without 3d states are necessary to properly describe the upper valence band spectra. A study of the core exciton feature seen in the X-ray emission spectra of silicon and other materials suggest that there is a relationship between the intensity and binding energy of the exciton. An explanation of this relationship based on a Wannier core exciton model is proposed. The model is tested by comparing the measured binding energies with the values predicted by dielectric constant and effective mass data. The temperature dependence of phonon broadening in undoped and heavily-doped silicon is used to determine the core hole phonon coupling constant. This coupling constant is approximately one for covalent silicon in contrast to metals and polar insulators, which have significantly larger coupling constants. A simple microscopic model based on bond properties between the core atom and nearest-neighbor atoms is developed to explain the weak coupling in covalent materials. The model is also used to explain differences between the valence band and exciton coupling strength in undoped and heavily-doped silicon.
- Research Organization:
- Virginia Univ., Charlottesville, VA (United States)
- OSTI ID:
- 7233077
- Resource Relation:
- Other Information: Thesis (Ph.D.)
- Country of Publication:
- United States
- Language:
- English
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SILICON
ELECTRONIC STRUCTURE
X-RAY SPECTRA
SILICON NITRIDES
DOPED MATERIALS
EMISSION SPECTRA
EXCITONS
LCAO METHOD
SOFT X RADIATION
CALCULATION METHODS
ELECTROMAGNETIC RADIATION
ELEMENTS
IONIZING RADIATIONS
MATERIALS
NITRIDES
NITROGEN COMPOUNDS
PNICTIDES
QUASI PARTICLES
RADIATIONS
SEMIMETALS
SILICON COMPOUNDS
SPECTRA
X RADIATION
664200* - Spectra of Atoms & Molecules & their Interactions with Photons- (1992-)