Suchergebnisse

A complete set of all optical phonon modes predicted by symmetry for bixbyite structure indium oxide is reported here from a combination of far-infrared and infrared spectroscopic ellipsometry, as well as first principles calculations. Dielectric function spectra measured on high quality, marginally electrically conductive melt grown single bulk crystals are obtained on a wavelength-by-wavelength (also known as point-by-point) basis and by numerical reduction of a subtle free charge carrier Drude model contribution(. )A four-parameter semi-quantum model is applied to determine all 16 pairs of infrared-active transverse and longitudinal optical phonon modes, including the high-frequency dielectric constant, epsilon(infinity) = 4.05 +/- 0.05. The Lyddane-Sachs-Teller relation then gives access to the static dielectric constant, epsilon(DC) = 10.55 +/- 0.07. All experimental results are in excellent agreement with our density functional theory calculations and with previously reported values, where existent. We also perform optical Hall effect measurements and determine for the unintentionally doped n-type sample a free electron density of n = (2.81 +/- 0.01) x 10(17) cm(-3), a mobility of mu = (112 +/- 3) cm(2)/(Vs), and an effective mass parameter of (0.208 +/- 0.006)m(e). Density and mobility parameters compare very well with the results of electrical Hall effect measurements. Our effective mass parameter, which is measured independently of any other experimental technique, represents the bottom curvature of the Gamma point in In2O3 in agreement with previous extrapolations. We use terahertz spectroscopic ellipsometry to measure the quasi-static response of In2O3, and our model validates the static dielectric constant obtained from the Lyddane-Sachs-Teller relation. Published under an exclusive license by AIP Publishing. ; Funding Agencies|National Science Foundation (NSF)National Science Foundation (NSF) [NSF DMR 1755479, NSF DMR 1808715]; Nebraska Materials Research Science and Engineering Center, GraFOx, a Leibniz-Science Campus - Leibniz Association-Germany [DMR 1420645]; Air Force Office of Scientific Research (AFOSR)United States Department of DefenseAir Force Office of Scientific Research (AFOSR) [FA9550-18-1-0360, FA9550-19-S-0003]; Swedish Research Council VRSwedish Research Council [2016-00889]; Swedish Foundation for Strategic ResearchSwedish Foundation for Strategic Research [RIF14-055, EM16-0024]; Swedish Governmental Agency for Innovation Systems VINNOVA under the Competence Center Program [2016-05190]; Knut and Alice Wallenbergs Foundation supported grant "Wide-bandgap semiconductors for next generation quantum components"; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University; Faculty Grant SFO Mat LiU [2009-00971]; University of Nebraska Foundation; J. A. Woollam Foundation