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 LiNb 1 -x Ta x 0 3 (abbreviated as LNT, with x= 0-1.0) thin films deposited on Pt(1 1 11)/TilSiO 2 /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 LiNb 0,8 Tau 0.2 O 3 had the largest voltage responsivity of 7020 (V/W) at 70 Hz, and a specific detectivity (D*) of 7.76 x 10 7 cm Hz 1/2 /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.