An investigation into the growth of magnesium niobium oxide and lead magnesium niobate by liquid-injection MOCVD using a magnesium-niobium alkoxide precursor

The double metal alkoxide Mg[Nb(OEt)(8)](2)(2EtOH) has been in investigated as a single-source precursor for the deposition of magnesium niobium oxide end lead magnesium niobate by liquid-injection MOCVD, The presence of Pb(t hd)(2) (thd =2,2,6,6-tetramethylheptane-3,5-dionate) has been shown to sign ificantly influence the deposition chemistry of the Mg/Nb alkoxide precurso r. In the absence of Pb(thd)(2) and at low substrate temperatures (similar to 425 degreesC) the Mg:Nb ratio in the oxide film grown from Mg[Nb(OEt)(8) ](2)(2EtOH) is close to 1:2, At higher substrate temperatures (500 degreesC ) the films are magnesium deficient, indicating partial decomposition of Mg [Nb(OEt)(6)](2)(2EtOH). However, in the presence of Pb(thd)(2), films grown from Mg[Nb(OEt)(6)](2)(2EtOH) at low temperature (425-500 degreesC) contai n no detectable Mg, whilst the 1 :2 Mg:Nb ratio, required for Pb(Mg0.33Nb0. 66)O-3, is now obtained at higher substrate temperatures (600 degreesC), Th is is attributed to the formation of a thermally-stable Mg beta -diketonate species via a gas-phase ligand exchange reaction between Pb(thd)(2) and Mg [Nb(OEt)(6)](2)(2EtOH). Copyright (C) 2000 John Wiley & Sons, Ltd.