The expertise of the group for the epitaxy of a wide range of semiconductor nanostructures allows together (i) to develop thematic explorations in material science (such as nucleation mechanisms or new forms of materials i.e. nanowires), (ii) to provide on demand samples for internal or external studies at the local, national and international levels, and (iii) to propose new kinds of nano-objects for new functionalities and potential applications.
Over the period, a special interest was paid to nanowire (NW) heterostructures, which open a way to grow quantum objects whatever the lattice mismatch with barrier material. In these structures, the quantum dot (QD) can be a thin slice of small gap material inserted in a narrow NW with a position, shape and size determined by the growth conditions, by contrast to the Stranski-Kratstanov QDs, which are due to a self-assembled process having the elastic strain relaxation as a driving force. This gives rise to a lot of new possibilities for the engineering of these QDs embedded into NWs : QDs of GaN, InGaN, GaAs, CdSe, CdTe, CdMnTe were inserted into NWs made of respectively AlN, GaN, AlGaAs, ZnSe, ZnTe barriers. Depending on the semiconductor compounds, the axial growth to achieve these NWs is a vapor-liquid-solid growth process, which is done either without any catalyst (nitrides), either with a self-catalyst (gallium for arsenides) or with a gold catalyst (II-VI materials). These nanowire based structures are optimized using both Molecular Beam Epitaxy (MBE) and Metal-Organic Chemical Vapor Deposition (MOCVD).
Besides this expertise, the control of the radial growth in these 1D structures was also developed ; it permits :
Moreover, the easy dispersion of NWs afterwards makes possible the study of structural, optical and electrical properties of single objects, which is one of the main research lines of our group.
We have developed the growth techniques for semiconductor nanowires based on different material systems such as III-N (InN, GaN, AlN], II-VI(,CdSe,ZnSe) and III-As (InAs, GaAs, AlAs). Currently, these nanowires have demonstrated single photon operation respectively in the UV and in the visible.... > suite
Our research aims to fabricate, study, and manipulate different forms of magnetic polarons embedded in semiconductors nanowires. One challenge is to make a link between the quantum limit (single magnetic impurity, single carrier), and ferromagnetic-like system involving an ensemble of magnetic impurities and several carriers confined in a quantum dot, or a one dimensional hole gas. It may open also new routes for semiconductor structures embedding ferromagnetic elements, in the search for higher ordering temperatures by wavefunction engineering, for controlled anisotropy by strain engineering, and for strong magneto-electric effects.
People : Edith Bellet-Amalric, Bruno Daudin, Henri Mariette Benoît Amstatt, Johann Coraux, Sébastien Founta Overview and results : Study of the growth and of structural and optical properties of GaN quantum dots (QDs) obeys several motivations, from both basic and applied research points... > suite
People : Régis ANDRE, Catherine BOUGEROL, Hervé BOUKARI, Henri MARIETTE, Serge TATARENKO. Thomas AICHELE, Laurent MAINGAULT, Rita NAJJAR, Ivan-Christophe ROBIN Results : CdSe/ZnSe self-organized QDs The case of CdSe differs from other strained materials such as Si/Ge or InAs/GaAs :... > suite