Structural, optical and photoelectric properties of Tb doped ZnO thin films for device applications

In this work we have investigated the effect of thermal annealing of thin ZnO:Tb3+ films obtained by the combined method of electrochemical deposition of Tb ions onto silicon substrates and subsequent reactive magnetron sputtering of a zinc target on the substrates on the structural properties, optical and photoelectric properties. ZnO:Tb3+ films with annealing temperature up to 700 degrees C are close-packed structures without porosity, with an almost smooth surface and dense packing of crystallites. The crystallite size and film thickness increase insignificantly with increasing annealing temperature. The films under investigation exhibit strong green luminescence with three bands in the spectral region of similar to 1.9-2.6 eV, caused by intracenter 4f transitions on Tb3+ ions without changing the redistribution in the relative intensity of three bands with an increase in the annealing temperature. The study of the photoelectric properties showed that with an increase in the bias voltage, the maximum of the spectral sensitivity in absolute value increases and shifts to the short-wavelength region, while with an increase in the annealing temperature, the photosensitivity decreases, and upon annealing at 1100 degrees C it is practically absent.