Growth of SmFeAsO1-x F x and NdFe1-x Co x AsO thin films by metal-organic chemical vapor deposition and post diffusion processes

Iron-based '1111' polycrystalline superconducting thin films have been successfully grown on (100) LaAlO₃ substrates by metal-organic chemical vapor deposition and an ex situ diffusion process. The viability of the method to grow NdFe_1-xCo_xAsO and SmFeAsO_1-xF_x compounds is presented. The x-ray diffraction, scanning electron microscopy and electrical measurements show that the formation of the superconducting quaternary phase is possible by this method. The different behaviors of electrical resistance as a function of temperature are explained and discussed in terms of the amount of 'doping' in the different ReFeAsO compounds as well as in terms of the spurious phases that appear together with the superconducting phase.