Effects of Annealing Temperature on Structural and Optoelectronic Properties of Zr-doped ZnO Thin Films for Photosensors

We investigated the effects of the annealing temperature on the optoelectronic properties of Zr-doped ZnO (ZZO) thin films deposited on glass substrates by radio frequency sputtering and annealed at 200, 300, and 400 °C.It was found by X-ray diffraction analysis that all the deposited thin films had a hexagonal crystal structure with polycrystalline grains oriented along the (0 0 2) direction.Furthermore, the film annealed at 400 ℃ had the lowest resistivity among the films due to the growth of grains, as well as the lowest resistivity of 1.5 × 10 -2 Ω•cm, a mobility of 35 cm 2 V -1 s -1 , and a carrier concentration of 4.2 × 10 19 cm -3 .It also had a maximum transmittance of 95% and an energy gap of 3.2 eV.These results show that ZZO thin films subjected to annealing at 400 ℃ are promising for use as stable photosensors.