Influence of substrate heating and annealing on the properties and photoresponse of manganese doped zinc oxide thin films

The structural and optical properties of manganese doped zinc oxide thin films deposited at different substrate temperatures and annealing conditions have been studied. Further, the UV light sensing properties of the fabricated thin film devices have been carried out. The 3% Mn doped ZnO (MZO) films were deposited by RF magnetron sputtering. The as prepared film, deposited without substrate heating, shows the polycrystalline nature with under-developed grains, which develops well-defined crystal boundaries after annealing. On the other hand, the films deposited at 700 degrees C and annealed at 700 degrees C show single crystalline c-axis orientated growth. Notably, there are changes observed in the band gap and photoluminescence of the films subject to different deposition and annealing conditions. The photoresponse of the MZO thin film devices shows responsivity varying from 2.5 x 10(-2) to 7.9 A/W, detectivity from 1.6 x 10(10) to 37.8 x 10(10) Jones and sensitivity from 4.7 to 15.4% under the UV light. Markedly, the films show the response times varying from similar to 0.1 to similar to 28 s and the recovery times varying between similar to 0.1 and similar to 120 s. These findings demonstrate the influence of structural and optical properties brought out by the substrate heating and annealing of 3% Mn doped ZnO films on the photoresponse of devices. (C) 2017 Elsevier Ltd. All rights reserved.