Annealing effects on the photoluminescence of terbium doped zinc oxide films

摘要

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 ℃). 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 ℃ up to 1000 ℃ by steps of 100 ℃ were performed. Chemical analyses by energy dispersive X-ray spectrometry measurements showed a constant dopant concentration of 3 at.%. Up to 600 ℃, the band gaps (E_g) decreased with T_a from 3.44 down to 3.37 eV. Above 600 ℃, the band gap raised from 3.37 up to 3.42 eV (for 900 ℃). Depending on T_a, a bi-axial stress was found varying from a compressive value of - 0.21 GPa (400 ℃) down to a tensile value of 0.05 GPa (1000 ℃). PL mechanisms of the Tb:ZnO film are then discussed.