Electro-Optical Properties of Hydrogenated Si-Doped CdO

Abstract

The optoelectronic properties of CdO films could be controlled and improved for transparent conducting (TC) purposes by means of doping. In the present work, several sets of CdO thin films hydrogenated and doped with different amounts of silicon were prepared on glass substrates by a thermal deposition technique in order to improve their TC properties. The x-ray diffraction method was used to study the crystal structural variations in CdO films as a consequence of Si(H) doping. Optical properties were studied by means of optical absorption and reflection spectroscopy. The observed blue-shifting in the optical bandgap by Si(H) doping was attributed to the Moss–Burstein effect with reduced structural bandgap by point defects created during the process of doping. The mechanism of the hydrogenation process was explained by the dissociation of hydrogen molecules into atoms/ions, which in turn interacted with structural oxygen ions leading to the creation of oxygen vacancies. The creation of oxygen vacancies caused increases in electron concentration (N el) and electrical conductivity (σ). The results showed that Si(H) doping of host CdO films significantly increased their conductivity, mobility, and carrier concentration by ∼ 69, 5.6, and 12.3 times, respectively. The results confirm that Si(H) doping is effective for using CdO films in transparent conducting oxide applications.