SIlicoN PHOtonics with diluted NItride Coherent integration – SINPHONIC

The SINPHONIC project aims to demonstrate the ability to integrate laser devices on silicon (Si) substrate within a very large scale (one of the last scientific locks for the development of optoelectronic integrated circuits on Si chip) with III-V semiconductors-based nanostructures.
One way which is followed in the SINPHONIC project, is to use monolithic and coherent (lattice-matched) crystalline growth of III-V semiconductors (well-known for their good optical properties) directly on Si. Particularly, the GaP0.97N0.03 III-V alloy, which is lattice-matched on Si, allows avoiding lattice mismatch related defects which degrade laser performances. Moreover, a LED device has been demonstrated by the young researchers within this consortium on GaP substrate. Decreasing of the defects density generated near the III-V-Si heterointerface in the SINPHONIC project should open the way for efficient electrical injection through the GaP interface. This would demonstrate the compatibility of these structures with the well-known CMOS technology on Si, for very large scale integration.
The present project relies on a new and unique in Europe equipment, available at FOTON-INSA laboratory: a LPCVD-MBE growth cluster. This cluster includes a LPCVD growth chamber dedicated to the growth of Si and its dopants, which is connected under ultra high vacuum to a MBE growth chamber for the III-V semiconductors in the GaP and diluted nitride family, with associated dopants. Heterogeneous growth are realised without air contamination, which allows keeping unpolluted epi-ready surface. We propose in the SINPHONIC project the achievement of GaPN/GaP/Si pseudo-substrates (doped or undoped), with a defect density compatible with the realization of laser sources, and the demonstration of efficient light emitter on Si.
Si homoepitaxial layer is first deposited, which aims to burry defects coming from chemical or thermal preparation of Si. During this step, impact of step bunching on the quality of subsequent epitaxial layers will be studied by RHEED and AFM observations. The ability to use nominal (001) Si substrate will be carefully examined, in order to check the compatibility with microelectronics industry. After ultra-high vacuum transfer to the MBE chamber, a thin GaP nucleation layer is then deposited (thinner than the critical thickness). Combined structural characterizations means will support the project (TEM, SEM, AFM, X-ray scattering) for a better understanding of first steps of GaP-Si heterogeneous growth. In addition to the conventional stacking faults and micro-twins created during the growth, anti-phase boundaries (which come from polar on non-polar growth) will be studied. Defects density will be controlled and limited as far as possible. The project will partly rely on an original method using X-ray diffraction, from lab or synchrotron sources, giving statistical information on sample anti-phase domains.
GaPN alloy which is lattice-matched and optically active on Si will then be deposited on GaP/Si. In addition to the previously cited structural characterizations, will join advanced optical characterizations (Photoluminescence (PL), Photoluminescence excitation, time-resolved PL) and electronic structure calculations (abinitio calculations, tight-binding) which allow determination of the origin of optical emission on Si: localization of excitons by clustering effects, contribution of nitrogen atoms to material bandgap, or screening of defects coming from the GaP/Si heterogeneous interface with nitrogen atoms accumulation. Finally, the SINPHONIC project will propose the realization of light emitters on Si, which will validate the overall good quality of the structures for laser devices and their electrical injection.