'CONTRAT DOCTORAL PRIORITAIRE' Intégration par épitaxie de composants III-V sur circuits photoniques Si

par Marta Rio Calvo

Projet de thèse en Électronique

Sous la direction de Eric Tournie et de Jean-Baptiste Rodriguez.

Thèses en préparation à Montpellier , dans le cadre de I2S - Information, Structures, Systèmes , en partenariat avec IES - Institut d'Electronique et des Systèmes (laboratoire) depuis le 30-09-2017 .

  • Résumé

    Beaucoup de molécules présentent des signatures liées aux énergies de vibration et rotation dans l'infra-rouge moyen (MIR). La spectroscopie d'absorption par diode laser accordable (TDLAS) permet donc la détection de nombreuses espèces chimiques ou biologiques, ce qui est crucial pour beaucoup d'applications à fort impact sociétal (surveillance de l'environnement (gaz à effet de serre), diagnostic médical, suivi de procédés,...). Les lasers à semiconducteurs à base de GaSb sont parfaitement adaptés pour ces applications, et de nombreux dispositifs ont été démontré. Néanmoins, il y a un besoin de miniaturisation croissante et de réseaux des capteurs. Les roadmaps technologiques proposent de développer ces capteurs à partir de circuits photoniques intégrés (PICs) en technologie Si. Il convient donc d'intégrer les lasers à semiconducteurs III-V sur ces PICs. L'objectif de la thèse est fabriquer des lasers à base de GaSb sur les PICs Si. Il s'agira de réaliser l'épitaxie par jets moléculaires des structures, de les caractériser, de fabricquer les composants et de les tester. Une étape préliminaire consistera à optimiser les lasers sur substrat Si.

  • Titre traduit

    Epitaxial integration of III-V devices on Si photonic circuits

  • Résumé

    Most molecules exhibit absorption fingerprints in the mid-infrared (MIR) wavelength range, due to rotational/vibrational energies of molecules. Tunable-diode laser absorption spectroscopy thus allows detection and concentration measurements of many biological and chemical species. This is of crucial interest for many societal applications such as health monitoring and diagnosis, detection of biological compounds, monitoring of toxic gases emitted by industries, or of greenhouse gas emission responsible for global warming, to name but a few. Exploiting MIR absorption spectroscopy requires the adequate MIR sources which should operate in continuous mode at room temperature, and emit a few mW of single-frequency output power. Such sources have been demonstrated in the past, and consist mainly in III-V antimony-based laser for the 1.8 – 3 µm wavelength range [1], and III-V interband cascade lasers [2] or quantum cascade lasers [3] for longer wavelength. In the past decade, discrete lasers have been demonstrated which cover the whole MIR wavelength range. However, there is an increasing need for smaller and smarter sensors. The objective is to develop miniaturized, connected sensors in view of establishing non-invasive, connected sensor grids. The technology trend indicates that these sensors will surely rely on Si photonic integrated circuits (PICs) where lasers and/or photodetectors are coupled to Si/SiO2 or Si/SiGe-based circuits which will allow transferring part of the complex III-V technology needed to get single mode operation to the well-established Si technology [4]. One of the main challenges is the integration of III-V devices. The most advanced approach today is undoubtedly the heterogeneous integration of III-V devices on a silicon platform which has been pioneered in the telecom wavelength range [5, 6] and is aimed at being extended to the MIR range [7, 8]. III-V heterostructures are first grown on their native substrates. Subsequently they are either processed into individual dies which are individually bonded onto the Si platform, or the whole III-V substrate is bonded to the Si platform before processing individual integrated devices. Thanks to several US and European projects, much progress has been made in the last decade on the heterogeneous integration of InP-based telecom lasers and optoelectronic devices [5, 6]. While this bonding approach has been quite successful the bonding process is not straightforward to implement to achieve efficient electrical injection and low thermal resistance. In addition, hybrid routes are particularly unfriendly in terms of environment, health and safety due to steps like polishing-off the III-V wafers. There is thus a need for another integration scheme based on the direct hetero-epitaxy of III V material on Silicon, as envisioned by the Silicon chip industry [9]. Epitaxial integration of III-V lasers on Si wafers has shown much progress in the past few years [10]. We have demonstrated CW operation of GaSb-based laser diodes grown on off-axis Si wafers in the 1.5 µm [11] and 2.0 µm [12] range. These results will form the bedrock of the project. In this PhD thesis the candidate will develop the growth of GaSb-laser directly on on-axis Si PICs in order to directly integrate laser sources with the dedicated optical functions. The PhD candidate will be involved in several of the following tasks: circuit design, growth by molecular-beam epitaxy of the devices, material characterization, laser processing, laser characterization. [1] For a review see, e.g., E. Tournié, A.N. Baranov, Advances in Semiconductor Lasers, edited by J.J. Coleman, A.C. Brice and C. Jagadish, in Semiconductors and Semimetals, vol. 86, pp. 183 – 226 (2012). [2] For a review see, e.g., I. Vurgaftman et al., J. Phys D: Applied Physics, 48, 123001 (2015). [3] For a review see Y. Yao et al., Nat. Phot.6, 432 (2012). [4] See, e.g., http://www.i-micronews.com/mems-sensors/8252-the-gas-sensor-market-is-about-to-change.html [5] For a review see, e.g., G.H. Duan et al., IEEE J. Light . Technol. 33, 976 (2015). [6] For a review see, e.g., T. Komljenovic et al., IEEE J. Light. Technol. 34 (1), 20 (2016). [7] G. Roelkens et al., IEEE J. Selected Topics in Quantum Electronics 20 (4), 8201511 (2014). [8] M. Muneeb et al., Opt. Expr. 24 (9), 9465 (2016). [9] http://www.iqep.com/research/IIIVonSi.asp [10] E. Tournié, J.B. Rodriguez, L. Cerutti, H.Y. Liu, J. Wu, and S.M. Chen, MRS Bulletin 41 (3), 218 (2016). [11] A. Castellano, L. Cerutti, G. Narcy, J.B. Rodriguez, A.Garreau, F. Lelarge,and E. Tournié, 19th International Conference on Molecular-Beam Epitaxy (MBE2016), 4 – 9 September 2016, Montpellier (France). [12] J.R. Reboul, L. Cerutti, J.B. Rodriguez, P. Grech, and E. Tournié, Appl. Phys. Lett. 99, 121113 (2011).