Effect of growth and electrical properties of TiOx films on microbolometer design

This paper presents the feasibility of non-stoichiometric TiOx thin films as an active material for bolometer application. The TiOx films have been deposited on glass substrate by DC sputtering with oxygen flow rate of 0.1-0.7 sccm at room temperature and their electrical properties have been studied. The TiOx films were found to be amorphous with dense and smooth surface morphology. The thickness of the films was found to decrease from 150 to 30 nm with an increase in oxygen flow rate. The TiOx film corresponding to 0.7 sccm showed maximum temperature coefficient of resistivity of 0.72%/degrees C. Performance of TiOx-based bolometer pixel (pitch: 56 mu m) is simulated using the electrical characteristics of the deposited films. The TiOx film corresponding to the 0.7 sccm O-2 flow rate displayed thermal conductance of 2.95 x 10(-7) W/K along with a maximum Figure of Merit of 2.45 x 10(6) and a time constant of 8.2 ms. The Noise equivalent temperature difference of the bolometer structure is estimated (similar to 107 mK).