FABRICATION AND CHARACTERISTICS OF Pb DOPED BST FERROELECTRIC THIN FILMS FOR UNCOOLED INFRARED FOCAL PLANE ARRAYS

ABSTRACT

(Ba_1-xSr_x)TiO₃ (BST) ferroelectric thin films with Pb doped from 1 to 10 mol % were fabricated on Pt/Ti/SiO₂/Si substrates by sol-gel technique in order to improve the crystallographic properties and decrease the ferroelectric relaxation and the diffuse phase transition. The microstructures, surface morphology, dielectric properties, and ferroelectric properties of BST thin films were studied. The Pb doping increased the BST grain size, lowered the diffusion phase transition, and narrowed the diffuse phase region of BST thin films. We found that 5 mol% Pb doped (Ba_0.8Sr_0.2)TiO₃ thin films show a strong preferential orientation of crystallites in (110), excellent ferroelectric properties, the better crystallographic properties, and low loss tangent, which is basically suitable for the detecting materials of uncooled infrared focal plane arrays (UFPAs). The 5 mol% Pb doped BST thin films with dielectric constant of 402, loss tangent of 0.011, remanent polarization of 3.8 μCcm⁻², a coercive field of 45 kVcm⁻¹ have been fabricated by using sol-gel process.

Keywords:

• Pb doping
• BST ferroelectric films
• crystal properties
• sol-gel
• diffuse phase transition

ACKNOWLEDGMENTS

This study was supported by the Major State Basic Research Development Program of China (973 Program No. 2004CB619300), and Program for New Century Excellent Talents in University (NCET-04-0703).