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Optical Characterization of As2Te3 Films for for Optical Interconnects
Published online by Cambridge University Press: 10 February 2011
Abstract
Absorption coefficient and refractive index measurements of stoichiometric As2Te3 thin films grown on Si and KBr substrates are presented. The films were grown by an organometallic deposition process where the sources for both As and Te react at reduced pressures and temperatures to produce stoichiometric films in the presence of a surface; no growth occurs otherwise. Films were grown at 300 and 373 K and had a thickness range of about 0.2–1.2 μm. The refractive index was sample independent and had strong dispersion near the optical gap, rapidly increasing from the value of 3.8 at 1.5 μm as the wavelength decreases. An interference technique was utilized to measure the absorption of the films since interference effects and substrate absorption bands hindered the application of conventional optical transmission techniques. The optical gaps, obtained from Tauc plots, were in the range 0.83–0.95 and the results confirm that the As2Te3 films behave as noncrystalline semiconductors, being either amorphous or partially crystalline. Amorphous films on Si had absorption in the range of optical transparency comparable to that of the substrate, films on KBr substrates had much higher absorption.
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- Copyright © Materials Research Society 1998
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