Improvement of the thermal stability of Nb:TiO_2−xsamples for uncooled infrared detectors

Abstract

In order to reduce the sun-burn effect in a sample of the bolometric material Nb:TiO2−x, oxygen annealing was carried out. This effect can be examined by comparing thermal stability test results between the as-deposited and oxygen-atmosphere-annealed samples under high-temperature exposure conditions. Structural studies confirm the presence of amorphous and rutile phases in the as-deposited and annealed samples, respectively. Composition studies reveal the offset of oxygen vacancies in the Nb:TiO2−x samples through oxygen-atmosphere annealing. The oxygen atoms were diffused and seemed to occupy the vacant sites in the annealed samples. As a result, the annealed samples show better thermal stability performance than the as-deposited samples. The universal bolometric parameter (β) values were slightly decreased in the oxygen-annealed Nb:TiO2−x samples. Although bolometric performance was slightly decreased in the oxygen-annealed samples, high thermal stability would be the most essential factor in the case of special applications, such as the military and space industries. Finally, these results will be very useful for reducing the sun-burn effect in infrared detectors.

TiO2−x films for bolometer applications: recent progress and perspectives

“…The diffusion mechanism of oxygen during annealing in the oxygen atmosphere is exhibited in figure 14(a). It is clearly shown that oxygen vacancies are offset by oxygen atoms diffusion during high-temperature annealing [60]. As shown in figure 14(c), the sample deposited at room temperature does not show the Raman spectra of TiO 2−x , indicating that the film is amorphous.…”

“…They annealed the samples at a high current to remove the ghost image, but the resistivity of annealed samples decreased. Therefore, increasing the current for annealing is not a fundamental solution to the ghost image [60].…”

“…Although the annealed samples' thermal metrology performance decreased slightly, the thermal stability was significantly improved compared with the deposited samples. This type of oxygen vacancy compensation method opens a new opportunity to enhance titanium oxide films' thermal stability and other oxide materials annealed in an oxygen atmosphere [60].…”

“…Chemical compositions of the as-deposited and annealed TNO samples. Reproduced from[60]. © IOP Publishing Ltd. All rights reserved.…”

Carbon Nanotube-Based Uncooled Bolometers: Advances and Progress

“…However, one limiting factor is that the synthesis of this material requires critical oxygen and temperature conditions and suitable sputter targets . Another material system that has shown good promise for use as an uncooled BM is the nonstoichiometric TiO 2– x /TiO x films. − These films are mostly grown with reactive magnetron sputtering or ALD with a near-RT absolute TCR value as high as 9%/K . Thermal annealing and Nb doping have proved to be successful schemes toward improving the bolometric response of these Ti oxide films.…”