Kinetic Study of the Metalorganic Chemical Vapor Deposition of PbTiO₃ Films from Pb(C₂H₅)₄/Ti(i-OC₃H₇)₄/O₂ Reaction System

Abstract

Lead titanate (PbTiO 3 ) films are prepared from mixtures of tetraethyl lead [Pb(C 2 H 5 ) 4 ], titanium tetraisopropoxide [Ti(i-OC 3 H 7 ) 4 ] and oxygen at temperatures ranging from 823 to 873 K by the low-pressure chemical vapor deposition (LPCVD) method. The kinetics of the film growth process has been studied, including investigating the growth rate dependency at various substrate temperatures and the concentrations of Pb(C 2 H 5 ) 4 , Ti(i-OC 3 H 7 ) 4 , and O 2 , respectively. A reaction model applying the Eley-Rideal mechanism is proposed to explain the experimental film growth rate dependency. The model involves (i) a strong surface adsorption species, Pb(C 2 H 5 ) 4 , chemisorbing on the substrate surface to react with a dissociatively adsorbed oxygen to form PbO, (ii) a less adsorptive species, Ti(i-OC 3 H 7 ) 4 , directly coming from the gas phase to react with the surface adsorbed species to form PbTiO 3 films. The proposed reaction model fits the growth rate data quite well.

Composition and Crystal Phase Control of Chemical-Vapor-Deposited Pb(Zrx,Ti1-x)O3 Films on Various Oxide Electrodes with Reactants Pb(C2H5)4, Zr(O-t-C4H9)4, Ti(O-i-C3H7)4 and O2

“…In a previous study of the kinetics of PZT film growth using a frequently-applied MOCVD reaction system with tetraethyl lead (Pb(C 2 H 5 ) 4 , or TEL), zirconium tert-butoxide (Zr(O-t-C 4 H 9 ) 4 , or ZTB), titanium tetraisopropoxide (Ti(Oi-C 3 H 7 ) 4 , or TTIP), and oxygen (O 2 ) as the reactants, we found that PZT film growth is dominated by a Langmuir-Hinshelwood reaction in which the adsorbed TEL and O 2 form PbO. 12,13) This result reveals that control of the PZT film composition may possibly be simplified by manipulating the key precursor reaction in the TEL/ZTB/TTIP/O 2 -CVD reaction system.…”

“…growth According to our recent study on the deposition of PZT films using the TEL/ZTB/TTIP/O 2 -CVD reaction system, the film growth rate obeys Langmuir-Hinshelwood kinetics with respect to TEL and O 2 , but is linearly proportional to the concentrations of the B-site precursors, i.e., ZTB and TTIP. 12,13) This means that among TEL, ZTB, and TTIP, TEL is the only precursor that shows a strong interaction with the substrate. Therefore, an Eley-Rideal mechanism that considers a surface reaction among two adsorbed species, TEL and O 2 , and two gaseous species, ZTB and TTIP, can describe the PZT film growth behavior as follows.…”