MONITORING OF MOCVD FABRICATION OF LAF_3 FILMS USING THE NOVEL LA(HFAC)_3contre dot DIGLYME ADDUCT AND 'IN SITU' SYNTHESIZED LA(HFAC)_3 ANHYDROUS PRECURSOR

摘要

MOCVD processes from II generation La(hfac)_3 * diglyme and "in situ" synthesized anhydrous La(hfac)_3 have been compared in horizontal, hot-wall reactor. Gas phase "in situ" FTIR measurements have demonstrated that the La(hfac)_3 contre dot diglyme is stable up to 300℃ under Ar. Higher temperatures result in precursor demolition pathways which lead to carbon contaminated LaF_3 films. The Ar/O_2 mixture favors the polyether dissociation just above 250℃. LaF_3 films with no carbon contaminants are deposited in these conditions. In the alternative route, the anhydrous La(hfac)_3 has been synthesized in situ by vapour-solid reaction between Hhfac and powder of La_2O_3 in the source reservoir of an MOCVD reactor. "In situ" gas phase FTIR spectra provide evidence that anhydrous La(hfac)_3 can be transported in the MOCVD reactor. Thin LaF_3 films with no carbon contaminations have been deposited in the 400-500℃ range using either O_2 or Ar as reaction gas.