Colossal magnetoresistive thin films for uncooled bolometer

A. Lisauskas; S. I. Khartsev; A. M. Grishin

doi:10.1117/12.417603

8 March 2001 Colossal magnetoresistive thin films for uncooled bolometer

A. Lisauskas, S. I. Khartsev, A. M. Grishin

Proceedings Volume 4318, Smart Optical Inorganic Structures and Devices; (2001) https://doi.org/10.1117/12.417603
Event: Advanced Optical Materials and Devices, 2000, Vilnius, United States

Abstract

Pulsed laser deposition technique has been employed to fabricate a continuous series of solid solutions with basic composition of La_0.7(Pb_{1- x}Sr_x)_0.3MnO₃, which undergo metal-to-insulator transition near the room temperature. These films exhibit colossal magnetoresistivity (CMR) and strong temperature dependence of resistivity in the vicinity of phase transition. Temperature coefficient of resistivity (TCR) has been tailored by precise compositional control tog et maximum value close to room temperature. Film with TCR as high as 7.4%K¹ at 295 K and magnetoresistance of 30% at 7kOe has been used to make uncooled bolometer demonstrator. The responsivity as high as 0.6 V/W, noise equivalent power of 3x10^-8W/(root)Hz, detectivity of 9x10⁶ cm(root)Hz/W, and noise equivalent temperature difference as low as 120 nK/(root)Hz at 30 Hz frame frequency have been achieved for non-optimized bolometer based on 4.5-micrometers - thick film grown on 2.5x2.5x0.5 mm³ LaAlO₃(001) substrate. Measurements of optical responsivity in frequency and time domains yield substrate-to-thermostat thermal conductance G = 3x10^-3 W/K and three relaxation times responsible for heat transfer from film thermistor to substrate, from substrate to thermostat, and heat exchange via leads to be 0.5 s, 1.9 ms and 90 microsecond(s) correspondingly. Improving bolometer design by micromachining technique, one can expect that reducing of thermal conductance G down to 10^-6 W/K for bolometer with resistance of 500 (Omega) , should result in the increasing of responsivities to 3.9 A/W and 2.8x10³ V/W and detectivities to 2.5x10⁸ cm(root)Hz/W and 9.3x10⁸ cm(root)Hz/W at 30Hz in voltage and current biasing regime correspondingly.

Citation Download Citation

A. Lisauskas, S. I. Khartsev, and A. M. Grishin "Colossal magnetoresistive thin films for uncooled bolometer", Proc. SPIE 4318, Smart Optical Inorganic Structures and Devices, (8 March 2001); https://doi.org/10.1117/12.417603

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