Optical conductivity tuning and electrical properties of a-BexZnyO thin films

• Thin films of amorphous BeZnO were grown by RF sputtering at T < 52 °C.
• Optical conductivities and electrical properties of the films examined
• The σopt values of the films were negligible in the VIS and NIR regions.
• The films revealed high σele and low σopt when the Be concentration is < 13%.
• The a-BexZnyO films with higher Be concentration have shown an insulating nature.

BexZnyO thin films were deposited on crystalline Si (100) and glass substrates at temperature T < 52 °C using RF magnetron sputtering. The X-ray diffraction result indicates that all films have an amorphous nature. By using X-ray photoelectron spectroscopy, the concentrations of Be and Zn atoms were determined. The optical conductivity (σopt) and the dielectric constants of the amorphous BexZnyO (a–BexZnyO) films were determined in the wavelength range 138–1650 nm. The electrical properties of the films for different Be concentrations were also investigated. Changes in the measured of the optical conductivity, the dielectric constants, and the electrical properties values by changing the Be doping level are described for a-BexZnyO films. The adding of Be content to the a-ZnO films has a strong effect on their optical and electrical properties which can be modified by controlling the amount of Be as a dopant. Thus, the a-BeZnO films are good candidates for achieving σopt modulation to values larger than a-ZnO films (1.53 × 1014 1/s, at 3.35 eV). Also, the σopt values were found very small above the bandgap energy, indicating that the films are transparent. The films showed an insulating nature with a huge resistivity of 7.05 × 104 Ω cm for a-Be0·13Zn0.38O0.52 film while the resistivity of a-ZnO film (without doping) exhibits the lowest value of 0.35 Ω cm. Furthermore, the correlation between electrical and optical conductivities of a-BexZnyO films for different Be concentrations has been studied. The amorphous films revealed high σele and low σopt when the Be concentration is < 13%.