Nanomaterials Growth Unit

• Pulsed laser deposition of epitaxial thin films and characterisation of different materials (mainly oxides), looking at strain and relaxation mechanisms, and the microstructural and functional properties of ultrathin films (metal-insulating transitions, ferroelectric, ferromagnetic, oxide ionic conducting, thermoelectric, transparent conducting, resistive switching, etc.)

• MOCVD growth of 2D layers of transition metal dichalcogenides

• Structural characterisation by RHEED and advanced XRD, and high temperature electronic transport properties

• Fundamental aspects of interfacial phenomena in layered oxide materials and multilayers for their use as components in ionic and protonic solid oxide fuel cells (SOFCs), as well as in resistive switching devices

• Accurate structural characterization of epitaxial thin films making use of advanced X-ray diffraction techniques (reciprocal space mapping under non-ambient conditions and external stimuli: gas change, voltage, illumination)

Our unit produces films by means of pulsed laser deposition and MOCVD techniques and works in close collaboration with many ICN2 research groups, as well as with external teams. A recently developed two-laser PLD setup allows co-ablation of two targets for deposition of films with composition gradient, as well as new mixed composition materials. Our unit carries out advanced structural characterisation of thin films, primarily by X-ray diffraction as well as working on the development of advanced methods for the characterisation by X-ray diffraction of epitaxial thin films. These include in-plane diffraction, GIXRD analysis, as well as 3D reciprocal space mapping. This microstructure research is complemented with HRTEM characterisation.

We are particularly interested in surface and interfacial phenomena, such as oxygen exchange kinetics. For this purpose we have developed a time-resolved XRD technique that monitors the subtle chemical expansion produced in transition metal oxide thin films when changing their oxygen stoichiometry. We aim to perform in-situ and in-operando characterisation by XRD in different solid state electrochemical devices. These studies have also been extended to in-situ structural studies of ferroelectric materials, and resistive switching, as well as photostricitive materials.

We have also continued working on the development of a thin film MOCVD process for the growth of high-quality ultrathin transition metal dichalcogenides, starting with MoS₂, in collaboration with the ICN2 group led by Prof. José A. Garrido.

Last year, we started working in collaboration of Prof. Gustau Catalan’s group on the fabrication of single-crystal free-standing membranes of perovskite oxides by using water-soluble sacrificial epitaxial layers in an attempt to implement functional oxides in a new generation of electronic devices. Currently, we are engaged in the fabrication of free-standing membranes of different ferroic oxide materials to analyse the intrinsic characteristics of strain-free ultrathin films.

CERCAGINYS is the access platform to the around 200 facilities of all the 41 CERCA institutes.