Epitaxy and remote epitaxy of ZnS and Zn1-xCdxS thin films with wurtzite crystal phase
Versailles, Yvelines
CDD
Temps-plein
Il y a 2 mois
Offer DescriptionFor many decades now, research on semiconductor thin films has been very active, has opened original fields of investigation in fundamental physics, and has enabled unique opportunities for applications in electronics, photonics, sensors, actuators, energy, and health. From the material point of view, this requires to fabricate epitaxial layers as perfect as possible since device performances largely depend on the crystalline quality of the materials used to fabricate them. In addition, semiconductors can be synthetized in other crystal phases than the standard one (phase of lowest energy), with different physical properties. This is known as polytypism, and this area of research offers great opportunities to tailor the properties of electronic materials like silicon or germanium.The first objective of the proposed PhD thesis is to fabricate and characterize ZnS and Zn1-xCdxS thin films in the hexagonal wurtzite phase, with thicknesses of a few tens of nanometers. ZnS commonly crystallizes in the cubic phase (zinc blende, ZB) but, growing on the suitable substrate, the epitaxy can lead to a hexagonal crystalline structure (wurtzite, WZ). The materials will be elaborated by using Metal-Organic Chemical Vapor Deposition (MOCVD), which is an industrial technique commonly employed in microelectronics. The morphology and the structural properties of the grown layers will be accurately characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), X-Ray diffraction and scanning transmission electron microscopy (STEM). In particular, the observation and study of the crystalline phase will be the focus of our attention.The second objective is to explore what is called "remote epitaxy" [1] where the thin film will be grown through a 2D material (graphene in this project) previously transferred on the substrate. Graphene suppresses strong chemical bonds, and hence the interaction with the deposited film is given by quasi Van-der-Waals bonds. However, the electrostatic potential of the underneath substrate is not totally screened, allowing for a coupling between the film and the substrate. That is believed to ensure a kind of epitaxy with respect to the underlying crystalline structure. But still, there are many fundamental open questions about this new process and its validity. Studying the remote epitaxy of WZ-ZnS films on ionic II-VI substrates will be unique in the community and of strong interest for the field.The PhD thesis is part of a national project funded by French National Agency for Research (ANR) and led by C2N Palaiseau.RequirementsResearch Field Physics Education Level Master Degree or equivalentSkills/QualificationsKnowledge: condensed matter, crystallography, physics of semiconductors.Skills: experimental work, communication (the PhD student will participate to national and international conferences), team-working, good English, ability to follow safety rules (possibly some work in cleanroom).Languages ENGLISH Level GoodResearch Field PhysicsAdditional InformationWork Location(s)Number of offers available 1 Company/Institute CNRS, University of Versailles, University Paris-Saclay Country France City Versailles Postal Code 78035 Street 45 avenue des Etats-Unis GeofieldWhere to apply E-mailvincent.sallet@uvsq.frContact CityVersailles WebsiteStreet45 avenue des Etats-Unis Postal Code78035 E-Mailvincent.sallet@uvsq.fr Phone+33139254488STATUS: EXPIRED