Low temperature direct crystallization of SrBi2(Ta1-xNbx)(2)O-9 thin filmsby thermal metalorganic chemical vapor deposition and their properties

Directly crystallized SrBi2(Ta1-xNbx)(2)O-9 (SBTN) films were deposited on (111) Pt/Ti/SiO2/Si substrates at 585-670 degreesC by thermal metalorganic chemical vapor deposition (MOCVD). The crystalline SBTN film was directly d eposited at 670 degreesC irrespective of the deposition rate, but its leaka ge current markedly decreased when the deposition rate decreased from 5.0 t o 2.1 nm/min. When the deposition rate was below 2.1 nm/min, an SBTN film w ith large ferroelectricity was deposited even at 585 degreesC, and strong ( 103)-orientation was ascertained by an X-ray reciprocal space mapping metho d. This orientation is considered to locally epitaxially occur on a (111)-o riented Pt substrate. Twice the remanent polarization (2P(r)) and twice the coercive field (2E(c)) of the film deposited at 585 degreesC were 12.2 muC /cm(2) and 160 kV/cm, respectively. When the deposition temperature increas ed, the film became randomly oriented which was in response to the orientat ion change in the Pt substrate from single (111) to a mixed orientation of (111) and (100) orientations by heating before starting the film deposition . 2P(r) and 2E(c) of the film deposited at 670 degreesC increased to 23.8 m uC/cm(2) and 190 kV/cm, respectively.