The Effect of Substrate Materials on Orientation Degree of Lanthanum-Substituted Bismuth Titanate Thin Films

Abstract

The effect of different substrates (Si, Pt/Ti/Si and quartz) on the orientation degree of Bi_3.4La_0.6Ti₃O₁₂ thin films was studied. Bi_3.4La_0.6Ti₃O₁₂ thin films were prepared by sol-gel process. X-ray diffraction (XRD) studies indicate the formation of the lanthanum-substituted bismuth titanate thin films. It is found that the orientation ratio along c-axis direction of Bi_3.4La_0.6Ti₃O₁₂ thin films deposited on various substrates were different. Bi_3.4La_0.6Ti₃O₁₂ thin films deposited on quartz substrate has relatively higher c-axis orientation degree (about 90%) than that on Si (86%) and Pt/Ti/Si (88%). The results of XRD pole figures indicate that Bi_3.4La_0.6Ti₃O₁₂ thin films deposited on quartz show a well-defined (006)-orientation. It is found that surface morphology of Bi_3.4La_0.6Ti₃O₁₂ thin films deposited on quartz substrate and Pt/Ti/Si contain spheroidal grains and sheet-like grains, respectively. The grain size of the former is about 65 nm, and 200 nm in diameter for the latter.

Keywords:

• Ferroelectric thin films
• (Bi,La)₄Ti₃O₁₂
• c-axis orientation degree
• Sol-Gel process