Thermally stimulated current analysis of Zn1-xCdxO alloy films

Research highlights: → We have studied the structural and electrical properties of Zn1-xCdxO alloy films deposited by ultrasonic spray pyrolysis technique. → The trap energy, the capture cross-section, the attempt-to-escape frequency and the concentration of the traps in Zn1-xCdxO films are reported. → The effect of the Cd incorporation into ZnO material on trapping levels was investigated by the TSC measurements. Two overlapped peaks were registered at levels of 0.033 and 0.197 eV in ZnO sample by the curve fitting technique. The observed trap energy levels for ZnO film is thought to originate from zinc interstitials and oxygen vacancies. However, the incorporation of Cd into Zn1-xCdxO alloy films with x = 0.59 have resulted in two trapping centers with activation energies of 0.118 and 0.215 eV. The observed trap levels in Zn0.41Cd0.59O alloy film are related to oxygen adsorption in the sample. - Abstract: We have studied the structural and electrical properties of Zn1-xCdxO alloy films deposited by ultrasonic spray pyrolysis technique. XRD measurement indicated that pure ZnO and CdO samples had single phases with hexagonal wurtzite and cubic structures, respectively. However, Zn1-xCdxO alloy films with x = 0.59 and 0.78 exhibited mixtures of a hexagonal wurtzite ZnO phase and a cubic CdO phase. Analysis of thermally stimulated current spectra of Zn1-xCdxO alloy films revealed the existence of a number of overlapped peaks each characterized by different trap energy levels located in the range of 0.033-0.215 eV below the conduction band. We have used curve fitting method for the evaluation of the trap parameters of the alloy films. The values of attempt-to-escape frequency ν, capture cross-section S and concentration of the traps Nt have been determined.