Optical and electrical properties of copper-doped nano-crystallite CdO thin films

• It was successfully prepared single crystalline phase CdO:Cu films.
• Cu doping increases transparency and deteriorates crystal structure.
• Good agreements between electrical and optical (through SF model) measurements.
• Mobility 82.5 cm2/V s and conductivity 1428.6 S/cm were found with 2.3% Cu sample.

Thin films of Cu-doped CdO (CdO:Cu) with different Cu% content were prepared in high vacuum on glass and Si substrates. The samples were characterised X-ray diffraction (XRD), optical spectroscopy, scanning electron microscope (SEM), and dc-electrical measurements. The XRD study reveals the formation of single crystalline phase CdO:Cu of CdO structure with a preferential [111] orientation. However, with increasing of Cu% content, the crystal structure was gradually deteriorated. SEM study shows formation of granular structure with rice shape grains of average size ∼500 nm. The optical study shows that Cu doping increased the films transparency with a slight blueshift for the bandgap. The calculated optical constants for pure and Cu-doped CdO were analysed with Forouhi–Bloomer (FB), Wemple–Didomenico (WD), and Spitzer–Fan (SF) models. Good agreements were obtained between electrical and optical (through SF model) measurements. The electrical measurements show that the utmost enhancement in mobility (82.5 cm2/V s) and conductivity (1428.6 S/cm) was found with 2.3% Cu sample. The optoelectronic study was analysed through the available BGW and BGN models that show close theoretical to the experimental results. In general, the films of CdO prepared with light Cu doping have optical and electrical characteristics suitable for various applications in material sciences and optoelectronic devices.

The dependence of electrical parameters (resistivity, carrier mobility, and carrier concentration) on concentration of Cu dopant in CdO thin films.Figure optionsDownload as PowerPoint slide