The Effect of Post-Fabrication Annealing on an Amorphous IGZO Visible-Light Photodetector

We demonstrate the effect of the thermal annealing temperature (250 and 300 degrees C) on the performance (photosensitivity and temporal photoresponse) of an amorphous indium-gallium-zinc-oxide (alpha-IGZO) photodetector based on the TFT structure to visible radiation. Analysis of photosensitivity was performed to assess various sensing parameters, such as photoresponsivity (R-ph), threshold voltage (V-TH) shift, and subthreshold swing (SS). The photosensitivity was improved as the wavelength of light decreased and the annealing temperature increased. This was analyzed based on the activation energy for the ionization of an oxygen vacancy (V-o) and the concentration of Vo in relation to the thermal annealing condition. The temporal photoresponse of the alpha-IGZO device are also presented. The photoresponse times improved as the annealing temperature increased, which was due to the increase in the concentration of V-o functioning as a generation and recombination center with increasing annealing temperature.