Improvement of sensing sensitivity based on green emissions from Er-doped (AlGa)2O3 films

Abstract

The temperature-dependent photoluminescence behaviors in green region of Er-doped (AlGa)2O3 films with different Al contents have been studied in the temperature range of 77–400 K. A reduced thermal quenching in green region was observed with the increase of host bandgap, resulting in an enhancement of green emissions. Subsequently, the temperature sensing properties of films were studied by using the fluorescent intensity ratio (FIR) technique based on the thermally coupled levels of 2H11/2 and 4S3/2 in Er3+. The enhanced thermal sensing properties were found with the increase of Al content in films. The absolute sensitivity of 0.0056 K−1 at 400 K was obtained at the Al content of 0.77, which is twice that of Ga2O3:Er film. Finally, the effect of adding Al content on the thermal effect induced by the laser pump power was investigated, and the results suggest that the thermal effect in all samples induced by the pump power can be negligible in this work. This work provides a useful insight for developing optical temperature sensors with high luminescence efficiency and sensitivity.