PhysIcAl properties of hybrid semimetal/semicoNductor III-V/Si maTerials – PIANIST

The monolithic integration of III-V semiconductors having excellent structural and optical properties on the low cost and technology mature silicon substrate was long ago considered as an unattainable holy grail for many materials and devices scientists. The situation changed recently with the various demonstrations of efficient III-V/Si devices for photonics and energy. Among the defects generated during the III-V crystal growth on the Si substrate, the so-called Antiphase Boundaries (APBs), were always considered as non-radiative recombination centres, that limit the devices (e.g. lasers or photovoltaic cells) performances. Recent results obtained within the present GLOSSI consortium seriously challenge this view. These results indicate that APBs are 2D vertical homovalent singularities that have many interesting fundamental physical properties which could be used for photonic devices or energy applications.
PIANIST is a fundamental PRC research project, which aims to control and explore the optoelectronic and transport properties of hybrid semimetals/semiconductors III-V/Si nano-materials, and assess their potential for ground-breaking industrial innovations in the field of photonics and green energy materials. The PIANIST project will focus on three main objectives:
O1: Explore the unusual optoelectronic properties of homovalent singularities nanostructures in III-V semiconductors grown on Si
O2: Clarify the impact of the homovalent singularities and dislocations on the remarkable transport properties of III-V/Si epitaxial layers.
O3: Propose new III-V/Si devices for photonics and energy taking advantage of the physical properties of these buried nano-materials
To reach the three objectives, the project, organized with 4 scientific Tasks, will need important materials developments (Task 1) by internationally-recognized laboratories in the field, for III-Sb/Si (MBE@IES) and III-P/Si (MBE-UHVCVD@I-FOTON). The choice of III-Sb and III-P materials was motivated by the observation of strong similarities on homovalent singularities properties between the two materials, despite very different bandgap, growth and structural properties, which allows a generalization of the concepts developed in the project, through the design of specific samples to characterize optoelectronic or transport properties. Importantly, I-FOTON and IES have the ability to grow GaAs/Si or InP/Si epilayers. The project will also need advanced structural characterizations, available through Transmission Electron Microscopy at C2N or Scanning Tunneling Microscopy at IPR. The ultimate structural properties will be cross-checked by advanced X-Ray Diffraction at C2N, IES, and I-FOTON. Temperature and power dependent PL experiments will be performed and analysed at IES and I-FOTON to clarify the electron-phonons interactions. Cathodoluminescence (CL) and time-resolved (TRCL) mappings will be carried out at C2N and Raman scattering mappings at IPR to explore the exciton-lattice coupling. Transport properties will then be investigated by a multiscale approach using Hall measurements (IPR), micro-4 probe measurements (IPR), conductive AFM (IES&C2N), KPFM (i-FOTON), and Ballistic electron emission microscopy (BEEM at IPR). The local optical and electrical probes used to reach the objective O1 and O2 will need the control of the lateral size of antiphase domains to extract quantitative information. Finally, these experimental studies will be supported theoretically by atomistic DFT calculations (i-FOTON) to describe the electronic structure, vibrational properties and dielectric constants of III-V/Si homovalent stoichiometric or non-stoichiometric singularities. On this basis, the transport mechanism and optoelectronic properties will be clarified. Novel concepts of photoelectric devices (Task 4) targeted in objective O3 will naturally emerge from the physical properties determined in Tasks 2 (Optoelectronic properties) & Task 3 (Transport properties).