Structural and optoelectrical properties of nanocrystalline Gd-doped CdO films prepared by sol gel method

• Published in: Journal of sol-gel science and technology Vol. 55; no. 3; pp. 348 - 353
• Main Authors: Dakhel, A. A., Ali-Mohamed, A. Y.
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01.09.2010; Springer; Springer Nature B.V
• Subjects: Carrier density; Ceramics; Chemistry; Chemistry and Materials Science; Colloidal gels. Colloidal sols; Colloidal state and disperse state; Composites; Crystal structure; Crystallinity; Doping; Electrical measurement; Electrical resistivity; Exact sciences and technology; Free electrons; Gadolinium; General and physical chemistry; Glass; Glass substrates; Inorganic Chemistry; Materials Science; Nanotechnology; Natural Materials; Optical and Electronic Materials; Original Paper; Semiconductors; Silicon substrates; Sol gel process; Sol-gel processes; Thin films; Unit cell; X-ray diffraction; X-ray fluorescence; X-rays; Degenerate semiconductors; TCO; Sol gel method; Cadmium-gadolinium oxide; Gd-doped CdO; Rare earth oxides; Film; X ray fluorescence; Doping; Glass; Mobility; Gadolinium; Thin film; Optical absorption; Nanocrystal; Wafer; Experimental data; Semiconductor materials; Conductivity; X ray diffraction; Substrate; Electrical measurement; Sol gel process; Cadmium oxide; Electrons; Crystalline structure
• ISSN: 0928-0707; 1573-4846
• DOI: 10.1007/s10971-010-2260-3

Gd-doped CdO thin films with various Gd concentrations have been prepared on glass and Si wafer substrates using sol gel technique. The films were characterised by X-ray fluorescence (XRF), X-ray diffraction (XRD), optical absorption spectroscopy, and dc-electrical measurements. XRF method was used to determine the %Gd content in the films while XRD was used to study the influence of Gd doping on the detailed crystalline structure. Experimental data indicate that Gd 3+ doping with level of less than 2.4% slightly enlarge the CdO crystalline unit cell. The bandgap ( E g ) of Gd-doped CdO suffers narrowing by about 13% due to a small (0.2%) doping level but with %Gd doping level larger than 2.4%, E g becomes wider than that of undoped CdO. The electrical behaviours of the Gd-doped CdO films show that they are degenerate semiconductors. The 2% Gd-doped CdO film shows increase in its mobility by about 92%, conductivity by 320%, and carrier concentration by 127%, relative to undoped CdO film. From transparent-conducting-oxide point of view, the Gd doping of CdO by sol gel method is not effective. Finally, the absorption in the NIR spectral region was investigated to be due to the free electrons.