Integration of III-Sbs with the Si technology
Staff: E. Tournié, M. Bahriz, L. Cerutti, J.B. Rodriguez.
PhD students: K. Madiomanana (2011 – 2015); A. Castellano (Alcatel-Lucent, 2013 – 2016); J. Tournet (PROMIS ITN, 2015 – 2018); M. Rio Calvo (2017 – 2020); L. Monge-Bartolome (REDFINCH project, 2018 – 2021).
Other collaboration: G. Patriarche, C2N, Palaiseau (France); A. Trampert, Paul-Drude-Inst., Berlin (Germany).
Past collaboration: G. Roelkens, U.Ghent, (Belgium).
Combining the maturity of the silicon technology with the optical and electrical properties of the III-V semiconductors is under active consideration for developing novel optoelectronic devices, like photonic integrated circuits (PICs) or high-frequency transistors. The main foreseen applications are datacom, integrated sensors and multi-junction solar-cells.
The most mature approach today to integrate III-Vs on Si is the heterogeneous integration. III-V heterostructures are first grown on their native substrates before being bonded as individual dies or as a whole wafer onto the Si platform. Still, on a longer term large scale integration of photonic circuits will more surely rely on the direct epitaxial growth of III-Vs on Si, i.e. the monolithic integration of optoelectronic devices on silicon as put forward on the road map of all electronics majors.
In the last decade, nanoMIR has been active in the two approaches, heterogeneous and monolithic integration, with more effort toward monolithic integration.
Regarding heterogeneous integration, we designed and grew dedicated III-Sb mid-IR lasers and photodetectors to be heterogeneously integrated on CMOS compatible platforms. Integration was performed by U. Ghent or by INL Lyon and CEA-LETI, depending on the project. Spectrometers or wavelength meters have been fabricated in collaboration with U. Ghent (Fig. 1). This activity is currently in stand-by.
Regarding monolithic integration, we investigate the direct growth of III-Sb compounds on Si substrates. We started with growth on offcut Si substrates to avoid the formation of antiphase domains and boundaries (APBs), a type of defect which generates shorts in devices and which should absolutely be avoided. After demonstrating cw operation of mid-IR laser diodes emitting near 2 µm (Reboul et al., Appl. Phys. Lett. 99 (2011) 121113) we returned to more fundamental studies of the initial growth stages. We have first established a simple and reliable ex-situ Si-surface preparation prior to epitaxy, and we have performed an in-depth study of the microstructure and defect properties of GaSb/Si epitaxial layers in collaboration with C2N, CEMES, INSA-Rennes and PDI-Berlin. These results allowed optimizing the growth initiation on miscut Si substrates, and to understand the origin of most defects. The data are available in a number of papers published in Acta Materiala, Appl. Phys. Lett., J. Cryst. Growth and Phys. Rev. Mat. Elaborating on this background we have demonstrated cw operation of GaSb laser diodes emitting near 1.5 µm (Fig. 2) and the first ever quantum cascade lasers grown on silicon (Fig. 3). We have also demonstrated the successful operation of an InAs/InAsSb IR photodetector (Durlin et al., IR Phys. 96 (2019) 39) and of a GaSb solar cell (Tournet et al., Sol. Mat. 191 (2019) 444) grown on Si.
To go further, and to open wider possibilities in terms of applications, we are currently working toward the epitaxial integration of these devices on on-axis Si substrates. On one hand we collaborate with several groups providing III-V on Si templates. On the other hand, we have implemented in-house a new III-V-on-Si nucleation stage. Exciting results have been achieved which will be reported soon.
Finally, we just started working on integrating optoelectronic devices on Si photonics integrated circuits as well as on SiGe-based platforms. This topic will be carried out through a new ANR project starting early 2020.