Pyroelectric Ta-modified LiNbO3 thin films and devices for thermal infrared detection

High-performance pyroelectric infrared (IR) detectors have been fabricated using tantalate-doped lithium niobate LiNb1−xTaxO3 (abbreviated as LNT, with x=0–1.0) thin films deposited on Pt(111)/Ti/SiO2/Si(100) substrates by diol-based sol–gel processing, in which, tantalate (Ta) is adopted as dopant in lithium niobate. The randomly oriented LNT thin film exhibits a relatively small dielectric constant and a large pyroelectric coefficient. The pyroelectric characteristics of detectors with various tantalate contents, as a function of modulation frequency, were investigated. It was found that LiNb0.8Ta0.2O3 had the largest voltage responsivity of 7020 (V/W) at 70 Hz, and a specific detectivity (D⁎) of 7.76×107 cm Hz1/2/W at 200 Hz. These results indicate that the LNT thin film with x=0.20 is most suitable for application as high-performance pyroelectric thin-film detectors.