Tailoring the colossal magnetoresistivity: La0.7(Pb0.63Sr0.37)0.3MnO3 thin-film uncooled bolometer

Epitaxial Ca, Sr, and Pb doped manganite films of various compositions and thickness have been prepared to tailor metal-to-semiconductor phase transition to room temperature. Continuous series of solid solutions La0.7(Pb1−xSrx)0.3MnO3 grown by the pulsed laser deposition technique were found to possess superior performance regarding the maximum of temperature coefficient of resistivity (TCR) @300 K. In these films phase transition temperature Tc ranges from 266 to 327 K. We have engineered the film of the optimum composition x=0.37 exhibiting the maximum of TCR=7.4% K−1 @295 K. Relatively low excess noise (normalized value γ/n of 3×10−21 cm3) has been achieved due to the epitaxial quality of the fabricated film. Using this film, infrared radiation bolometer demonstrator, operating at room temperature, has been built and tested. The bolometer resolves the noise equivalent temperature difference as low as 120 nK/Hz and shows signal-to-noise ratio SNR=8×106 Hz/K, responsivity R=0.6 V/W, detectivity D=0.9×107 cmHz/W, and noise equivalent power NEP=3×10−8 WHz at 30 Hz frame frequency. For micromachined thermally isolated La0.7(Pb0.63Sr0.37)0.3MnO3 thin-film bolometer one can expect to get responsivity about 4×103 V/W and detectivity higher than 109 cmHz/W @30 Hz.