Epitaxial Integration of III-V optoelectronic devices on Si – OPTOSI

The very objective of this project is the realization of III-V lasers directly grown on Si substrates and the evaluation of the potential for their massive integration on Si based technology.
Task 1 will perform the growth and related routine characterizations of III-V/Si platforms following the two complementary approaches presented above. Optimized conditions of the Si surface preparation and the III-V/Si nucleation layer will be sought to favour defect annihilation or confinement close to the interface. Besides, task 1 will determine the growth parameters to obtain high quality wafers in both LMM III-Sb/Si and LM GaP(N)/Si materials systems. Buffer layers will be exchange between partners to investigate independently the impact of material polarity and lattice mismatch.
Task 2 deals with thorough and detailed microstructure investigations and on studies of the optical and electronic properties of the templates and of the active nanostructures (quantum dots, quantum wells) grown on these templates. The results will be feedback to define new growth parameters in order to optimize these templates. In addition, GaP- and GaSb- based nanostructures designed to emit at the target wavelengths will be grown on the templates and thoroughly characterized and modelled.
Task 3 will be devoted to the modelling, growth, processing and characterization of the various III-V lasers on the platforms provided by Task 1 and according to the active zone designs delivered by Task 2. An important effort will address processing issues such as cavity formation or contact location for discrete devices. These III-V on Si lasers will be thoroughly investigated in order to benchmark them against standard InP lasers. Preliminary ageing tests will also be performed since the lifetime of III-V on Si lasers is a notorious issue. Note in this respect that the interconnect application will require much relaxed specifications as compared to usual telecom lasers.

GaSb-based laser epitaxially grown on Si and suited for telecom
GaP(N) based laser epitaxially grown on Si and emitting near 900 nm

OPTOSI aims at demonstrating the monolithic integration of III-V optoelectronic devices on Si wafers with an emphasis toward Si photonics applications. The work programme will be based on the investigation and evaluation of the direct molecular-beam epitaxy (MBE) growth of III-V compounds onto Si substrates following two complementary routes:
1. the metamorphic, lattice-mismatched (LMM) route using an approach based on the unique strain-relaxation properties of III-Sb materials grown on highly mismatched substrates. Relaxation occurs by formation of a network of misfit dislocations confined near the interface which leads to low threading defect densities.
2. the quasi lattice-matched (QLM) route relying on GaP-based materials which can be lattice matched to the Si substrate and offer the perspective to bypass the issue of the relaxation defect formation.

These III-V/Si platforms will be used as templates to grow III-Sb and GaP(As,N) based lasers in order to fully evaluate the potential of these approaches for future Si photonics. New nanostructures will be investigated in each technology in order to deeply enter into the 1.1 – 1.5 µm wavelength range, the III-Sb and GaP(N) routes approaching from the long- and short- wave range, respectively.

OPTOSI brings together 4 leading French Academic Partners (IES-Montpellier, FOTON-Rennes, LPN-Marcoussis, LPCNO-Toulouse) with complementary expertises covering the fields of material sciences, device physics and device technology. One industrial research partner (3-5 lab) supplements the consortium to evaluate the results in terms of industrial perspectives.

If successful, the project will offer a new route to the integration of III-V devices on Si, and it will have a large impact well beyond the Si-photonics field since it will open the way to the integration of any kind of III-V devices on Si, such as MOS transistors expected from the ITRS roadmap or high-efficiency solar cells.

The importance of the field is reflected by the fact that the next “Compound Semiconductor week”, a large professional event which aims at “defining the next steps for the compound semiconductor industry”, will be dedicated to integration of III-Vs with Si (http://www.cseurope.net).