Electrical and Optical Investigations on Tungsten-Incorporated CdO Thin Films

Transparent conductive oxide tungsten-incorporated cadmium oxide (CdO) thin films were deposited on glass substrates by a vacuum evaporation technique. The structural, electrical, and optical properties have been investigated as functions of tungsten (W) doping content. The results show that W ions occupy structural interstitial positions in addition to accumulating on crystallite and grain boundaries. The bandgap of W-incorporated CdO films suffers narrowing that was studied within the framework of the available phenomenological models. The electrical study shows that W-incorporated CdO films are degenerate semiconductors. The lowest resistivity of 3.85 x 10(-4) Omega cm was achieved, with carrier mobility of 39.2 cm(2) V-1 s(-1) and carrier concentration of 4.13 x 10(20) cm(-3), for W incorporation of 0.1%. The average transmission attained was similar to 80% in the near-infrared (NIR) spectral region, with the optical bandgap ranging from 1.77 eV to 2.0 eV.