Structural analysis of Cd–Te–O films prepared by RF reactive sputtering

• Published in: Journal of non-crystalline solids 2008-08, Vol.354 (31), p.3756-3761
• Main Authors: Caballero-Briones, F., Peña, J.L., Martel, A., Iribarren, A., Calzadilla, O., Jiménez-Sandoval, S., Zapata-Navarro, Á.
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; II–VI semiconductors; Microcrystallinity; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of specific thin films; Optical spectroscopy; Physics; Raman scattering; Raman spectroscopy; Short-range order; Sputtering; Structure and morphology; thickness; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Tellurites; Thin film structure and morphology; X-ray diffraction
• ISSN: 0022-3093; 1873-4812
• DOI: 10.1016/j.jnoncrysol.2008.03.042

Crystalline and microcrystalline Cd–Te–O samples have been obtained by RF reactive sputtering from a CdTe target using N 2O as oxidant. The growth conditions were substrate temperatures of 323 K, 573 K and 773 K and cathode voltage of −400 V, corresponding to 30 W of forward power. The samples were studied by micro-Raman spectroscopy, X-ray diffraction and optical transmittance. The films are remarkably transparent in the visible range, with transmittances about 88% at 400 nm and band gap energies above the absorption edge of the glass substrates. Although only the samples prepared at 773 K present defined diffraction peaks, the analysis of the Raman spectra indicate that samples prepared at 323 K and 573 K have a defined microstructure indeed. The spectra fitting performed by comparison with pattern compounds demonstrate that Cd–Te–O films are formed of Te–O units similar to those present in metal oxide-doped tellurite glasses, such as TeO 3 and TeO 3 + 1 linked through Cd–O bonds. As the substrate temperature increases the microstructure evolves from a γ-TeO 2 richer state to Cd x Te y O z . In the crystalline sample the main phase identified was CdTeO 3 even though evidence of other phases was observed.