ANTIPODE

ANTIPODE is a fundamental research project which aims to deeply understand the formation of III-V/Si semiconductor interfaces in order to better control the defect generation at the interface during epitaxial growth. The project proposes to investigate three different III-V semiconductor materials, not only because they are all highly relevant for photonic applications (from UV to IR), but also because they allow to span the nucleation strain from compressive to tensile and close to zero. Although quite different, these three semiconductor materials exhibit a common 3D nucleation growth mode during the very-early stage of the growth on silicon substrates. This project mainly dedicated to state of the art characterization and modeling tools, aims to provide a unified and helpful understanding of III-V/Si semiconductor interfaces and their electronic properties. On December 10, 2012 IBM announced a breakthrough optical communication technology which has been verified in a manufacturing environment. This technology breakthrough allows the integration of different optical components side-by-side with electrical circuits on a single silicon chip, for the first time, in standard 90nm semiconductor fabrication. Despite the very promising results obtained with this “combined front-end” optical on-chip integration, the development of laser sources on chip is still the limiting issue in this integration scheme. To increase the level of photonics integration in a mid-term perspective, one of the most powerful and economical way is to perform the direct epitaxy of III-V semiconductors on the silicon chip. This idea has been widely studied in the early 80’s, where III-V on silicon devices were realized at an advanced level especially by growing the well-known GaAs directly on silicon. In these works, crystalline defects were found to be generated mainly at the III-V/Si heterointerface, and propagating in the volume. This route was revisited recently by three leading French laboratories which demonstrated advanced III-V optical functionalities/emitters on silicon with the growth of respectively the GaSb/AlSb (at IES Montpellier), GaP/AlP (at FOTON Rennes) and GaN/AlN (at CRHEA Valbonne) materials systems on Si. The heteroepitaxy of these materials on Si at the “front-end” level would be a very promising industrial solution provided that the III-V optical active area remains very close to the III-V/Si interface (typically below 300 nm) to increase the level of integration. In this context, the common strategies to manage the defects limitation engineering are not pertinent, as they require thick III-V buffer layers. The only solution is to control the defects generation at the III-V/Si interface and limit their propagation. From their previous experience, IES, FOTON and CRHEA acknowledge the same fact: the overall III-V materials quality is fully determined by the quality of the interface, i.e. by the initial Si surface, and the first III-V monolayers. Partners of the ANTIPODE project will study the initial stages of III-V/Si nucleation by MBE. To this end, they will benefit from the control of the initial Si surface (UHVCVD-MBE growth cluster), state-of-the-art advanced structural/electronic characterizations in three internationally recognized laboratories (HRTEM or STEM-HAADF available at CEMES-Toulouse and LPN-Marcoussis, synchrotron XRD or STM-BEEM available at IPR-Rennes) and theoretical support (atomic relaxation models, DFT, local charges and dipole). The ANTIPODE project is built around the three following objectives: O-I - understanding the 3D nucleation mechanism of III-V semiconductors on silicon (including generation of defects during coalescence) and the strain relaxation mechanisms. O-II - understanding the nature and role of the interfacial charges (in both III-V/Si interfaces and III-V defects interfaces) on the growth and defects generation. O-III - understanding of the influence of the initial silicon surface.