التفاصيل البيبلوغرافية
| العنوان: |
Ellipsometric studies on ZnO:Al thin films: Refinement of dispersion theories |
| المؤلفون: |
Ehrmann, Nicole ehrmann@isfh.de, Reineke-Koch, Rolf |
| المصدر: |
Thin Solid Films. Dec2010, Vol. 519 Issue 4, p1475-1485. 11p. |
| مصطلحات موضوعية: |
*ZINC oxide thin films, *ALUMINUM, *SILICON, *SUBSTRATES (Materials science), *ELLIPSOMETRY, *DISPERSION (Chemistry), *ANISOTROPY, *ATOMIC force microscopy, *TRANSMISSION electron microscopy, *GLASS |
| مستخلص: |
Abstract: We characterize sputter-deposited aluminum-doped zinc oxide (ZnO:Al) thin films on glass and silicon substrates by variable-angle spectroscopic ellipsometry in the spectral range of 240nm to 1700nm. The model dielectric function includes the excitonic effects of direct band-gap semiconductors in the presence of high carrier densities as well as the scattering of free carriers by ionized donors. We show that an energy-dependent broadening term of the band-gap model avoids an extended absorption tail below the absorption threshold as it usually results from Lorentzian broadening. Uniaxial anisotropy takes account of the oriented growth of hexagonal crystalline ZnO:Al thin films. All the parameters derived from the optical measurements such as surface roughness, free-carrier concentration and mobility agree with the results of independent thin-film characterization methods such as atomic-force microscopy, Hall and four-point probe measurements. In the case of the glass samples, we need an additional interface layer which is confirmed by transmission-electron microscopy as an intermix layer of ZnO and glass. [Copyright &y& Elsevier] |
| قاعدة البيانات: |
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