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International audience; The direct epitaxy of III-V lasers on Silicon (Si) substrates has been considered for decades as an important objective for the realization of integrated photonics chips. However, the difference in crystal structure, lattice-constant, thermal expansion coefficient as well as issues related to the reactivity of the Si surface have made this topic extremely challenging. For that reason, the direct epitaxy of lasers having good performance and decent lifetime on Si was considered as an almost unattainable dream, and many labs and companies have thus developed ways to circumvent this issue using hybridization techniques. However, major progress has been achieved recently thanks to a better understanding of the defect generation mechanisms, and systematic studies of their suppression [1], or at least the drastic reduction of their density into the active region of the device. In this presentation, we will discuss the challenges related to the growth of III-Vs on Si as well as the progress made lately in that field. We will then discuss the current state-of-the-art of mid-IR lasers grown on Si [2]. GaSb diode lasers (DLs) with GaInAsSb/AlGaAsSb quantum well active zones emitting near 2.3 µm exhibit record threshold current-densities near 200 A.cm-2. Their threshold current density is however sensitive to the threading-dislocation density that generate non radiative recombination [3,4]. In contrast, InAs/AlSb quantum cascade lasers emitting near 8 µm demonstrated performances similar to those on native InAs substrates, thanks to the short radiative lifetimes and the unipolar nature of the radiative process [5]. Finally, at intermediate wavelength (3.5 µm), InAs/GaInSb type-II interband cascade lasers also proved to be relatively insensitive to dislocations, which is ascribed to their particular band structure, their performance being similar to those achieved on native GaSb substrates [6]. These results open the route to active photonic integrated circuits operating in the mid-infrared for sensing applications [7].

International audience; MBE Growth of Mid-Infrared Lasers on Silicon Eric Tournié, M. Rio Calvo, L. Monge-Bartolome, A. Gilbert, A. Remis, M. Paparella, D. Andres Thomas, Z. Loghmari, R. Teissier, A. N. Baranov, L. Cerutti, and J.-B. RodriguezIES, University of Montpellier, CNRS, Montpellier, FranceAmong “More-than-Moore” strategies, the integration of optical devices with Silicon has attracted much attention. Indeed, mastering efficient light-emitting, energy harvesting, or light-engineering systems on silicon not only holds several advantages for present technologies (e.g., silicon photonics, photovoltaics, or sensors), but it could open novel paradigms in photonics, computing or energy harvesting and storage applications (e.g., integrated quantum photonics, all-optical neuromorphic computing, or solar water splitting). The epitaxial hybridization of III-V devices on Si however has long been hampered by the high defect density generated during the growth. One of the issues arises from the non-polar diamond crystal structure of Si, whereas III-V materials (but III-N compounds) have a polar zinc-blende crystal structure. This generally results in the nucleation of III-V anti-phase domains (APDs), and generates anti-phase boundaries (APBs) where main and anti-phase domains intersect. APBs create shorts and are device killers in most devices. After reviewing these issues and the current understanding , I will present strategies to eliminate APBs with a focus on the GaSb-on-Si case system. I will show how specific Si substrate preparation and III V-on-Si nucleation allow achieving APB-free GaSb-based layers and heterostructures on on-axis (001)Si substrates. More precisely, on a properly prepared Si surface, the different growth rates of the main and anti-phase domains results in the main domain overgrowing the APDs. Consequently, APBs are buried within the buffer layer after a thickness that depends on the residual Si miscut angle. Such “emerging-APB-free” GaSb-on-Si layers have been used as templates for the subsequent growth of a variety of mid-infrared lasers. The I – V characteristics of GaSb diode lasers emitting near 2.3 µm confirmed that APBs are no more an issue in these structures. Low threshold current-densities and high T0 characteristic of the devices have been obtained. Their threshold current density was however sensitive to the threading-dislocation density. In contrast, InAs/AlSb quantum cascade lasers emitting near 8 µm demonstrated performances similar to those on native InAs substrates, thanks the unipolar nature of the radiative process. Finally, at intermediate wavelength (3.5 µm), InAs/GaInSb type-II interband cascade lasers also proved to be relatively insensitive to dislocations, which is ascribed to their particular band structure. These results open the route to active photonic integrated circuits operating in the mid-infrared for sensing applications. Part of this work was sponsored by the French program on “Investments for the Future” (EquipEx EXTRA, ANR-11-EQPX-0016), the French ANR (ANR14-CE26-0014, ANR-16-CE24-0011) and the H2020 program of the European Union (project REDFINCH, GA 780240 ; OPTAPHI, GA 860808).References: I. Lucci et al., Phys. Rev. Mat. 2, 060401(R) (2018). https://doi.org/10.1103/PhysRevMaterials.2.060401 C. Cornet et al., Phys. Rev. Mat. 4, 053401 (2020). https://doi.org/10.1103/PhysRevMaterials.4.053401. M. Rio Calvo et al., Adv. Electron. Mat. 8(1), 202100777 (2022). https://doi.org/10.1002/aelm.202100777 M. Rio Calvo, L. Monge Bartolomé, et al., Optica, 7(4), 263 (2020). https://doi.org/10.1364/OPTICA.388383 Z. Loghmari et al., APL Phot. 5, 041302 (2020). https://doi.org/10.1063/5.0002376. L. Cerutti et al., Optica, 8(11), 1397 (2021). https://doi.org/10.1364/OPTICA.438272 E. Tournié et al., Light: Science & Applications. https://doi.org/10.1038/s41377-022-00850-4

International audience

Technological platforms offering efficient integration of III-V semiconductor lasers with silicon electronics are eagerly awaited by industry. The availability of optoelectronic circuits combining III-V light sources with Si-based photonic and electronic components in a single chip will enable, in particular, the development of ultra-compact spectroscopic systems for mass scale applications. The first circuits of such type were fabricated using heterogeneous integration of semiconductor lasers by bonding the III-V chips onto silicon substrates. Direct epitaxial growth of interband III-V laser diodes on silicon substrates has also been reported, whereas intersubband emitters grown on Si have not yet been demonstrated. We report the first quantum cascade lasers (QCLs) directly grown on a silicon substrate. These InAs/AlSb QCLs grown on Si exhibit high performances, comparable with those of the devices fabricated on their native InAs substrate. The lasers emit near 11 µm, the longest emission wavelength of any laser integrated on Si. Given the wavelength range reachable with InAs/AlSb QCLs, these results open the way to the development of a wide variety of integrated sensors.

International audience

В работе предложен зондовый метод, позволяющий визуализировать области выхода излучения из поверхности сколотых полупроводниковых лазеров с субволновым разрешением. Метод основан на детектировании в вакуумных условиях сдвига резонансной частоты зонда, связанной с нагревом балки либо кончика зонда излучением. Scanning probe method is proposed that allows to visualize regions of light emission on the cleavage surface of semiconductor lasers with a subwavelength resolution. The method is based on detecting under vacuum conditions of a shift in the resonant frequency of the probe related with the cantilever or probe tip heating by laser radiation.