Terbium doped zinc oxide (Tb:ZnO) films were deposited by radio frequency magnetron sputtering on (100) single-crystalline silicon substrates at low temperature (T-S = 100 degrees C). In this work, structural changes, optical properties and the associated photoluminescence (PL) responses are analyzed upon the annealing treatments. Post-annealing treatments from annealing temperature T-a = 400 degrees C up to 1000 degrees C by steps of 100 degrees C were performed. Chemical analyses by energy dispersive X-ray spectrometry measurements showed a constant dopant concentration of 3 at.%. Up to 600 degrees C, the band gaps (E-g) decreased with Ta from 3.44 down to 3.37 eV. Above 600 degrees C, the band gap raised from 3.37 up to 3.42 eV (for 900 degrees C). Depending on Ta, a bi-axial stress was found varying from a compressive value of -0.21 GPa (400 degrees C) down to a tensile value of 0.05 GPa (1000 degrees C). PL mechanisms of the Tb:ZnO film are then discussed. (C) 2013 Elsevier B. V. All rights reserved.