Influence of postdeposition annealing on the structural and optical properties of cosputtered Mn doped ZnO thin films

The influence of postgrowth annealing on the structural and optical properties of rf cosputtered Mn doped ZnO thin films deposited on glass substrate at room temperature has been investigated. All as deposited Zn1-xMnxO films are highly textured, with the c axis of the wurtzite structure along the growth direction. The as grown films are in a state of compressive stress and a reduction in stress with postgrowth annealing treatment are observed. The band gap of Mn doped ZnO films (3.34 eV) is slightly larger than the pure ZnO film (3.30 eV) and is found to decrease with an increase in annealing temperature for all the samples. The optical dispersion of refractive index with photon energy in Zn1-xMnxO films with varying x and different annealing temperature is studied in the light of single oscillator and Pikhtin-Yas'kov [Sov. Phys. Semicond. 15, 81 (1981)] model, respectively. (C) 2006 American Institute of Physics.