We have determined the dielectric functions of ZnO:Ga and ${\mathrm{In}}_{2}{\mathrm{O}}_{3}:\mathrm{Sn}$ with different carrier concentrations by spectroscopic ellipsometry. The dielectric functions have been obtained from ellipsometry analyses using the Drude and Tauc-Lorentz models. With increasing Hall carrier concentration ${N}_{\text{Hall}}$ in a range from ${10}^{19}\phantom{\rule{0.3em}{0ex}}\text{to}\phantom{\rule{0.3em}{0ex}}{10}^{21}\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}3}$, the dielectric functions of ZnO:Ga and ${\mathrm{In}}_{2}{\mathrm{O}}_{3}:\mathrm{Sn}$ show drastic changes due to increases in (i) free-carrier absorption in a low-energy region and (ii) the Burstein-Moss shift in a high-energy region. The analyses of the dielectric functions revealed reductions in high-frequency dielectric constant ${\ensuremath{\epsilon}}_{\ensuremath{\infty}}$ and increases in plasma energy ${E}_{\mathrm{p}}$ as ${N}_{\text{Hall}}$ in the films increases. From a set of the parameters $({N}_{\text{Hall}},\phantom{\rule{0.2em}{0ex}}{\ensuremath{\epsilon}}_{\ensuremath{\infty}},\phantom{\rule{0.2em}{0ex}}{E}_{\mathrm{p}})$ determined experimentally, effective mass ${m}^{*}$ of ZnO:Ga and ${\mathrm{In}}_{2}{\mathrm{O}}_{3}:\mathrm{Sn}$ is extracted. In contrast to previous studies, we found linear increases in ${m}^{*}$ with increasing ${N}_{\text{Hall}}$. When the variations of ${m}^{*}$ with carrier concentration are taken into account, carrier concentrations determined optically from spectroscopic ellipsometry show remarkable agreement with those estimated by Hall measurements. Nevertheless, the electron mobility obtained from spectroscopic ellipsometry and Hall measurements indicates rather poor agreement. We attributed this to the presence of grain boundaries in the films. In this article, we discuss various effects of carrier concentration on the optical properties of transparent conductive oxides.

Effects of carrier concentration on the dielectric function of ZnO:Ga and In 2 O 3 : Sn studied by spectroscopic ellipsometry: Analysis of free-carrier and band-edge absorption

Systematic investigation of the role of compact TiO2 layer in solid state dye-sensitized TiO2 solar cells

A method for forming a conductive thin film includes depositing a metal oxide thin film on a substrate by an atomic layer deposition (ALD) process. The method further includes at least partially reducing the metal oxide thin film by exposing the metal oxide thin film to a reducing agent, thereby forming a seed layer. In one arrangement, the reducing agent comprises one or more organic compounds that contain at least one functional group selected from the group consisting of —OH, —CHO, and —COOH. In another arrangement, the reducing agent comprises an electric current.

Method of growing electrical conductors

This invention relates to manufacturing of integrated circuits (ICs) and especially conductive layers suitable for use in an IC. According to the preferred method a metal oxide thin film is deposited on a substrate surface and reduced thereafter essentially into a metallic form with an organic reducing agent. The metal oxide is preferably deposited according to the principles of atomic layer deposition (ALD) using a metal source chemical and an oxygen source chemical. The reduction step is preferably carried out in an ALD reactor using one or more vaporized organic compounds that contain at least one functional group selected from the group consisting of —OH, —CHO and —COOH.

Method of growing electrical conductors by reducing metal oxide film with organic compound containing -OH, -CHO, or -COOH

This study addresses the ability of a conducting metal oxide to act as a material capable of supporting surface plasmon polaritons (SPPs). By use of a two-phase Fresnel model that provides insight into the difference between polariton-induced and absorptive decreases in reflectivity, indium tin oxide (ITO) is compared to the noble metals gold and silver, which are widely used as materials for surface plasmon resonance (SPR) detection of analytes. The study builds on application of the Drude free electron model that provides an explanation for the observed optical extinctions as a function of ITO film thickness, including the dependence of wavenumber on angle, by use of only two adjustable parameters, the plasma frequency ωp and the damping Γ. Herein, models of the dispersion and absorption include both the real and imaginary parts of the dielectric function to obtain the plasma absorption spectra and dispersion curves for ITO, Ag, and Au. ITO is found to have surface plasmon dispersion curves and plasma a...

Surface Plasmon Polaritons and Screened Plasma Absorption in Indium Tin Oxide Compared to Silver and Gold

Sputtered tin‐doped indium oxide (ITO) coatings were investigated by UV‐visible spectroscopic ellipsometry at different angles of incidence. The results were fitted using a classical dispersion formula for the optical constants of ITO in a model structure with a compact homogeneous film and a top layer representing surface roughness. Typical values for the high‐frequency dielectric constant e∞ and the plasma frequency ωp were found to be 3.4–4.0 and 0.68–0.96 eV, respectively. The influence of oxidative and reducing annealing at 400 °C was studied. No difference was observed under reducing conditions, but oxygen annealing reduced the influence of the plasma frequency on the studied UV‐visible region significantly. To prove the usefulness of the dispersion formula, TiO2 and Nb2O5 films were grown on ITO by metalorganic chemical vapor deposition using Ti(acac)2(i‐pro)2 and Nb(OEt)5 as precursors. These bilayers were studied by spectroscopic ellipsometry and could be successfully described applying the previ...

Optical properties of tin‐doped indium oxide determined by spectroscopic ellipsometry

Conducting thin films on RuO2 were deposited on glass by metalorganic chemical vapor deposition using tris‐trifluoroacetylacetonate‐ruthenium (III) [Ru(tfa)3] as precursor. Smooth, specular, and well adherent films were grown at temperatures as low as 400 °C, if the reaction gas contained water. RuO2 was the only phase detected by x‐ray diffraction. The films were investigated by spectroscopic ellipsometry in the energy range of 1.5 to 5.0 eV. Thereby, the real (e1) and imaginary (e2) parts of the dielectric function were determined at room temperature. The optical constants could be described by three harmonic oscillators in combination with a Drude term for free‐charge carriers.

Spectroscopic ellipsometry of RuO2 films prepared by metalorganic chemical vapor deposition

Reference LPI-ARTICLE-2000-020doi:10.1002/1521-3862(200008)6:4 3.0.CO;2-QView record in Web of Science Record created on 2006-02-21, modified on 2017-05-12

Tobias Gerfin

Papers

Optical properties of tin‐doped indium oxide determined by spectroscopic ellipsometry

Spectroscopic ellipsometry of RuO2 films prepared by metalorganic chemical vapor deposition

MOCVD of thin ruthenium oxide films : Properties and growth kinetics