Growth of bismuth titanate films by chemical vapor deposition and chemical solution deposition

Abstract

Bismuth titanate, Bi₄Ti₃O₁₂ (BIT) was grown via chemical vapor deposition (CVD) and chemical solution deposition (CSD). The BIT films were grown by CVD, with triphenylbismuth and titanium isopropoxide. BIT films were fabricated by CSD using a solution prepared with bismuth ethylhexanoate and titanium butoxyethoxide dissolved in butoxyethanol. What is readily apparent in both CVD and CSD BIT films, is that composition plays a dominant role in determining not only phase purity but texturing as well and that a small composition variation can lead to dramatic changes in phase purity, orientation and electrical properties. In the CVD BIT films composition was controlled by changing the growth temperature. In the CSD BIT films composition was controlled by changing the solution composition. CVD BIT films crystallized at lower temperatures with better crystallinity and greater c-axis texturing than the CSD BIT films at comparable Bi/Ti composition. For both CVD and CSD, titanium rich films contained a mixture of randomly oriented BIT and pyrochlore with generally lower remanent polarization values. For both the CVD and CSD films, c-axis texturing was observed to increase with increasing bismuth content. Bismuth rich films were typically strongly c-axis textured with generally lower remanent polarization values. The highest remanent polarization was obtained for stoichiometric randomly oriented CSD films.

Key Words:

• bismuth titanate
• ferroelectric
• chemical solution deposition
• chemical vapor deposition