Liquid injection MOCVD and ALD studies of “single source” Sr-Nb and Sr-Ta precursors

Abstract

ABSTRACTA range of “single source” Sr-Nb and Sr-Ta heterometal alkoxides precursors are investigated as potential sources for liquid injection MOCVD (metalorganic chemical vapour deposition) and ALD (atomic layer deposition) of SrBi2Ta2O9 (SBT) and SrBi2(TxNb1-x)2O9 (SBTN). These “single source” precursors are designed to alleviate the mis-match between conventional Sr and Ta or Sr and Nb sources. Strontium-tantalate and strontium-niobate thin films were deposited on silicon using the “single source” alkoxide precursors [Sr{Ta(OEt)5(dmae}2] and [Sr{Nb(OEt)5(dmae)}2] (dmae = OCH2CH2NMe2), and the optimum temperatures for deposition of stoichiometric SrTa2O6 and SrNb2O6 were determined. Separate ALD studies of [Sr{Ta(OEt)5(dmae)}2] and [Sr{Ta(OEt)5(mee)}2] (mee = OCH2CH2OMe) for the growth of strontium-tantalate were carried out to assess precursor suitability for this technique. Liquid injection MOCVD of Bi-oxide films using Bi(mmp)3 indicates similar decomposition behaviour to the Sr-Ta and Sr-Nb alkoxides, demonstrating its suitability as a complementary source of Bi for SBT, SBN and SBTN.