Uncooled bolometer response of a low noise La2/3Sr1/3MnO3 thin film

TL;DR

This study demonstrates the low-noise, high-sensitivity optical response of La2/3Sr1/3MnO3 thin films at room temperature, showing potential for competitive uncooled bolometer applications with further sensitivity improvements.

Contribution

First measurement of optical response and noise characteristics of La2/3Sr1/3MnO3 thin films, highlighting their potential for high-performance uncooled bolometers.

Findings

Low noise Hooge parameter among reported values

High optical sensitivity at 533 nm wavelength

Potential for three orders of magnitude NEP reduction with membrane geometry

Abstract

We report measurements of the optical responses of a La2/3Sr1/3MnO3 (LSMO) sample at a wavelength of 533 nm in the 300-400 K range. The 200 nm thick film was grown by pulsed laser deposition on (100) SrTiO3 substrate and showed remarkably low noise. At 335 K the temperature coefficient of the resistance of a 100 micrometers wide 300 micrometers long LSMO line was 0.017 K-1 and the normalized Hooge parameter was 9 e-30 m3, which is among the lowest reported values. We then measured an optical sensitivity at I = 5 mA of 10.4 V.W-1 and corresponding noise equivalent power (NEP) values of 8.1 e-10 W.Hz-1/2 and 3.3 e-10 W. Hz-1/2 at 30 Hz and above 1kHz, respectively. Simple considerations on bias current conditions and thermal conductance G are finally given for further sensitivity improvements using LSMO films. The performances were indeed demonstrated on bulk substrates with G of 10-3 W.K-1. One could expect a NEP reduction by three orders of magnitude if a membrane-type geometry was used, which makes this LSMO device competitive against commercially available uncooled bolometers.