Resonant photoemission characterization of SnO

Abstract

A thick layer of SnO, equivalent in its electronic properties to the bulk material, has been investigated by means of resonant photoemission and the mathematical method of factor analysis. This study has shown that O2p, Sn5s, and Sn5p partial density of states are the main contributions to the valence band of this material. The distribution through the valence band of these partial contributions has been determined by spectral subtraction and factor analysis of the resonance photoemission spectra, as well as by band structure calculation. The resonance behavior ͑i.e., change in intensity with the photon energy͒ of these three contributions has been analyzed. The Sn5p levels present a typical Fano-like behavior with a minimum intensity at about 28 eV and a maximum at 40 eV. The Sn5s partial density distribution also depicts a change in intensity as a function of the photon energy with a minimum situated at 35 eV and a maximum at 55 eV. Tentatively, this behavior has been linked to the existence of a broad absorption feature detected by electron energy loss spectroscopy and constant final state spectra, both depicting a broad maximum at about 50 eV. ͓S0163-1829͑99͒07339-7͔

Tuning surface properties of SnO2(101) by reduction

“…For tin-monoxide these Sn-5s states are being filled and form the top of the valence band. As a consequence SnO 2 has a larger band gap of approximately 3.6 eV while the band gap of SnO is significantly smaller [6,7]. Thus it may be assumed that the reduced SnO 2 (1 0 1) surface ( Fig.…”

Structural properties, infrared reflectivity, and Raman modes of SnO at high pressure

“…The electronic structure of SnO has been studied extensively within density functional theory, focusing on the static and dynamic properties and chemical stability [4], phonon modes and their contribution to the specific heat [7,8], the interpretation of the X-ray photoemission spectra [9,10], and the chemical bonding [11 -14]. In contrast to SnO 2 , the Sn atoms in SnO are left with two electrons in 5s states.…”

The origin of the electron distribution in SnO

“…This is in line with x-ray photoelectron spectroscopy 19 which shows that on reduction of SnO 2 , which has a band gap of 3.6 eV, additional features that are attributed to the Sn 5s states appear close to the Fermi level, giving rise to a much smaller gap between the occupied and unoccupied states. Recent photoemission spectra 20 has also studied the valence states of SnO and again show a small band gap with a significant contribution of the Sn 5s to the states just below the Fermi level.…”

“…It is this shift in energy that gives rise to the small band gap and corresponds to the Sn 5s character seen experimentally just below the top of the valence band. 19,20 The difference between the two EDOS is close to the Fermi surface where there is some Sn 5s character but the majority of it is involved in bonding interaction with O 2p between Ϫ9 and Ϫ6 eV. Partial electron density maps have been made for energy ranges of the EDOS.…”