Influence of hydrogenation on the electrical and optical properties of CdO thin films

The electrical and optical properties of CdO films post-annealed in hydrogen atmosphere for different durations (15 min, 30 min and 60 min) were studied. The prepared films were subjected to structural characterization by the x-ray diffraction method and optical characterization by the UV-VIS-NIR absorption spectroscopy method. Experimental data indicate that annealing in H-2-atmosphere slightly compresses the CdO unit cell and widens the energy gap of CdO from 2.31 eV to 2.42 eV via a Burstein-Moss energy level shift. The optical properties were easily explained within the framework of Hamberg et al band-to-band transitions and classical Drude theory. It was found that the greatest enhancement of electrical parameters that related to the transparent-conducting-oxide (TCO) function occurs by annealing in H-2-atmosphere for 30 min when the resistivity decreases, the conduction carrier concentration increases and the mobility increases. The results of the present work are important from a technical point of view for TCO production.