Pulsed injection MOCVD of functional electronic oxides

A new source has been developed in LMGP and in Vilnius University for the g eneration of active gases for chemical vapour deposition of layers. The pri nciple is a sequential injection of micro amounts (few milligrams) of a sol ution of organic precursors into an evaporator, where a flash volatilizatio n occurs. The system is very dierent from the other liquid sources currentl y used for the MOCVD process, the main advantages are: For a fixed injection parameter, the thickness of the layer is only determi ned by the number of drops injected ('digital growth') The system uses a flash evaporation: only one source containing a solution of the dierent precursors In an organic solvent Is required for the synthes is of complex compounds, but, of course, it is possible to use one source f or each element. Multilayers or superlattices of complex compounds are obtained with several injection sources connected to the same reactor and working alternately. A wide variety of compounds and multilayers have already been grown using t his new CVD source. In the field of high-temperature superconductors, high- quality YBa2Cu3O7 epitaxial layers have been recently obtained on 3 inch La AlO3 single-crystal substrate(T-c=92.1 K, DeltaT(c)=0.15 K, J(c)(77K)=4-6 M A/cm(2) over the whole surface). This demonstrates that the large amount of carbon existing in the gas phase does not aect the properties of the super conductor. Copyright (C) 2000 John Wiley & Sons, Ltd.