Autostoichiometric vapor deposition of ferroelectrics - the stoichiometry of co-evaporations

Abstract

The stoichiometry control in MOCVD of multicomponent oxide ferroelectrics is studied by a comprehensive approach. Experimental results on the stoichiometry of chemically controlled co-evaporation are reported. The temperature dependence of the vapor pressures for single alkoxides Ta(O C_nH_2n+1)₅ and Nb(O C_nH_2n+1)₅ are compared with those of double alkoxides LiTa(O C_nH_2n+1)₆ and LiNb(OC_nH_2n+1)₆. The stoichiometry of evaporation processes for the double alkoxides under various conditions is studied by controlled sublimation along with the composition analysis of both the sublimate and the residue. It is found that the stoichiometry of co-evaporation depends on the relative partial pressure of the single alkoxides at the respective evaporation temperature.

Key Words:

• stoichiometry
• MOCVD
• LiTaO₃
• LiNbO₃
• precursor