This study presents the integration of an Interband Cascade Laser (ICL) source emitting at 4 µm onto a silicon-germanium photonic platform, achieved through the Micro-Transfer Printing (µTP) technique. To our knowledge, this study reports the first demonstration of an integrated mid-infrared laser on SiGe.

The dislocation dynamics in epitaxially strained GaSb/AlSb/GaSb heterostructures grown on a Si(001) substrate via molecular beam epitaxy have been studied by means of scanning transmission electron microscopy. The 100 nm-thick AlSb layer - intentionally inserted as dislocation filter - is partially relaxed by bending pre-existing threading dislocations of the GaSb buffer into the interface with AlSb, creating a complex network of misfit dislocations. In addition to the expected misfit dislocation lines along the orthogonal (110) directions, irregular curved lines are also detected. Plan-view lamellae of the as-grown heterostructure were annealed in-situ in the microscope at temperatures well above the growth temperature to observe the propagation and interaction of the dislocations in real time. It was found that the (thermally activated) motion of misfit dislocations occurs independently of their Burgers vectors within the interface plane, which is not one of the primary slip systems of zincblende crystal structure, and without affecting the threading dislocation configuration in the filter layer. This unusual dislocation motion at this later stage of plastic relaxation (already 50% of lattice mismatch is relieved in the as-grown heterostructure AlSb layer) can only be explained by a non-conservative dislocation climb process on the one hand, and a vacancy-assisted slip on the other hand as it was recently discovered using molecular dynamics modeling. The results provide deeper insights into the thermal activation of dislocations in epitaxially strained systems and reveal potential for re-examining the conditions of those epi-layers as dislocation filters.

Quantum spin Hall transport in InAs/GaInSb-based two-dimensional topological insulators can be limited by parasitic bulk and edge contributions. We demonstrate that these limitations are effectively mitigated through electrostatic control in dual-gated InAs/GaInSb/InAs trilayer quantum wells grown on AlSb quasi-substrates. In macroscopic Hall bars exceeding the phase coherence length, a multi-probe analysis reveals an insulating bulk and a constant edge resistance over a wide electric-field range. In microscopic devices with edge lengths below the phase coherence lengths, the edge resistance remains robust and quantized accross a broad field range, revealing the intrinsic resilience of helical edge channels to electric-field perturbations. Only beyond a threshold value, parasitic edge contributions emerge. These results establish dual gating as a reliable strategy to suppress parasitic conduction while stabilizing helical edge transport, providing a versatile and reproducible platform for tunable topological transport in III-V quantum spin Hall systems.

We successfully fabricated interband cascade lasers (ICLs) emitting at 4.7 mu m on GaSb, GaAs, and Si substrates, demonstrating threshold current densities between 212 and 288 A/cm2 in pulsed operation at room temperature. While ICLs on mismatched substrates exhibited higher series resistance, they showed lower thermal resistance, suggesting that reducing series resistance could improve device performance. All lasers operated in continuous-wave mode up to 30 degrees C, and aging tests on ICLs grown on Si over 500 hours showed no performance degradation. These results confirm the tolerance of ICLs to dislocations, even at longer wavelengths.

A single mode distributed feedback (DFB) interband cascade laser (ICL) grown on a (001) Si substrate has been developed. The designed DFB ICL with a grating on top of the ridge emits at a wavelength near 3.4 μm, suited for methane gas sensing, and operates in continuous wave up to 35 °C, with a maximum output power of 4 mW/facet at 15 °C and a side mode suppression ratio of 20 dB in the whole operating range. Methane detection has been demonstrated by integrating the DFB ICL on Si with a quartz-enhanced photoacoustic spectroscopy setup, a step forward in the development of integrated photonic gas sensors on silicon platforms.

Overcoming the limitations of the von Neumann architecture requires new computational paradigms capable of solving complex problems efficiently. Quantum and neuromorphic computing rely on unconventional materials and device functionalities, yet achieving resilience to imperfections and reliable operation remains a major challenge. This has motivated growing interest in topological materials that provide robust and low-power operation while preserving coherence. However, integrating coherent topological transport with non-volatile memory functionality in a single reconfigurable device has remained challenging. In this work, we demonstrate a topological field-effect memristor based on inverted InAs/GaInSb/InAs trilayer quantum wells operating in the quantum spin Hall regime. The intrinsic floating-gate behavior allows one to reconfigure the transistor functionality into memristive functionality with broad electric-field tunability. Unlike other memristor implementations, one resistance state is governed entirely by dissipationless, coherent transport through helical edge channels, while the other arises from incoherent bulk conduction. By combining electrically tunable coherent and incoherent transport with memory functionality, our device realizes a prototypical topological electronic element that integrates coherent transport and adaptive memristive behavior, paving the way for hybrid quantum-neuromorphic architectures.

The quantum spin Hall effect (QSHE), a hallmark of topological insulators, enables dissipationless, spin-polarized edge transport and has been predicted in various two-dimensional materials. However, challenges such as limited scalability, low-temperature operation, and the lack of robust electronic transport have hindered practical implementations. Here, we demonstrate the QSHE in an InAs/GaInSb/InAs trilayer quantum well structure operating at elevated temperatures. This platform meets key criteria for device integration, including scalability, reproducibility, and tunability via electric field. When the Fermi level is positioned within the energy gap, we observe quantized resistance values independent of device length and in both local and nonlocal measurement configurations, confirming the QSHE. Helical edge transport remains stable up to T = 60 kelvin, with further potential for higher-temperature operation. Our findings establish the InAs/GaInSb system as a promising candidate for integration into next-generation devices harnessing topological functionalities, advancing the development of topological electronics.

Abstract The monolithic integration of III‐Vs on Silicon (Si) is of great interest for the development of active photonic integrated circuits (PICs). The main challenge is to achieve a high‐quality epitaxy of the III‐V on the Si substrate, as the differences between the materials are responsible for the formation of crystal defects, in particular threading dislocations (TDs) and antiphase domains (APDs) delineated by antiphase boundaries (APBs), which degrade the device's performance. A new technique is demonstrated to achieve thin APBs‐free GaSb buffer layers grown on Si substrates. The original idea presented in this paper is to introduce a GaAs layer into the buffer to promote faster burial of APDs. Two strategies are compared; the first one involves the complete APDs burying in GaAs before growing GaSb, while the second one uses a thin GaAs layer before burying the APDs in the GaSb layer. APB‐free buffer layers as thin as 215/400 nm have been obtained using the first method, which represents a factor of 2/4 thickness reduction compared to the previous results for both 0.5° and 0.2° miscut angles.

We propose a strategy to monolithically integrate active III-V lasers and passive dielectric devices, where the passive waveguides are fabricated after the MBE growth of the III-V semiconductors on a planar Si substrate. This avoids any airgap at the active/passive interface, replaced by a thin dielectric interface layer which improves the light coupling efficiency. We demonstrate GaSb DLs butt-coupled to SiN waveguides with ∼23% transmission after 2 mm SiN, corresponding to ∼35% transmission at the active/passive interface. We propose several routes to further increase the transmission factor. This strategy eliminates the need for trenches or pockets, which have been shown to cause poor quality material near the dielectric stack facet and to affect the laser lifetime. This strategy thus paves the way for an optimized route to monolithically integrate active and passive photonic devices with a high light coupling efficiency.

GaSb-based interband cascaded lasers (ICLs) have now become a leading laser source to cover the mid-infrared (mid-IR) spectral range (3-6 µm). In the last decade, the success of the silicon photonics industry thanks to its optical properties, low cost and easy commercialization of its large wafers size. However, this requires all Sb-based optoelectronics functions on a Si platform. We will discuss about our recent results on single mode distributed feedback interband cascade lasers (ICL) directly grown on Si emitting between 3 and 4 µm.

We present a multiprobe transport analysis that effectively separates bulk and edge currents in large Hall bar devices with standard geometries. Applied to transport measurements on all possible four-probe configurations of six-probe Hall-bar devices made of inverted three-layer InAs/(Ga, In)Sb quantum wells (QWs), our analysis not only reveals the presence of dissipative edge currents in the topological gap, but also allows the temperature dependence of bulk and edge conductivity to be evaluated separately. The temperature dependence of the edge conductivity for Hall-bar channels from 10 to 70 mu m in the range of 1.5 to 45 K is consistent with the theoretical expectation of weakly interacting helical edge electrons with backscattering due to localized magnetic moments of charge impurities. We argue that these charge impurities are naturally associated with intrinsic Ga-antisite defects, which act as double acceptors in InAs/(Ga,In)Sb-based QWs.

We report on Sb-based interband cascade lasers simultaneously grown on GaSb, GaAs and Si substrates. 8 µm x 2 mm devices exhibited similar threshold currents around 40 mA at 20°C and achieved continuous-wave (CW) operation up to 65°C on GaSb, GaAs and Si substrates despite a dislocation density of ∼ 4.108 cm-2 for both mismatched substrates. In the CW regime the output power of the devices emitting at 3.3 µm exceeded 30 mW/facet at 20°C. ICLs on GaAs and Si were subsequently aged at 50°C with an injection current of 200 mA, i.e. five times the laser-threshold current. No degradation was observed after 500 h of CW operation, demonstrating the high performance of ICLs and their tolerance to dislocations.

In this talk we will review our recent demonstrations of mid-IR lasers grown on (001) Si or Ge substrates (diode lasers, interband cascade lasers, quantum cascade lasers) and compare their performance to those grown on their native substrates. We will demonstrate light coupling from lasers grown on patterned Si photonics wafers to passive SiN waveguides, with a coupling efficiency in line with simulations. Finally, we will discuss and evaluate strategies to enhance the coupling efficiency.

Interband cascade lasers typically have significantly lower threshold current and power consumption than quantum cascade lasers. They can also have advantages regarding costs and compactness with the photonic integration onto silicon substrates by epitaxial growth. This research introduces a novel examination of the relative intensity noise and the modulation dynamics of a silicon-based Fabry–Perot interband cascade laser emitting at 3.5 μm. The investigation delves into crucial parameters, such as relaxation oscillation frequency, differential gain, gain compression, and K-factor. The resonance patterns identified in relative intensity noise curves can provide essential insights for the thorough characterization of high-defect mid-infrared semiconductor structures intended for high-speed applications. Moreover, this study demonstrates the feasibility of reaching 10 Gbit/s free-space transmission using a silicon-based interband cascade laser in conjunction with an interband cascade infrared photodetector.

AbstractThe monolithic integration of III‐V semiconductors on Si emerges as a promising approach for realizing photonic integrated circuits. However, the performance and reliability of epitaxially grown devices on Si are hampered by the threading dislocation density (TDD) generated during the growth. In this study, the efficiency of a structure, combining III‐Sb‐based insertion layers and thermal annealing is evaluated, on the reduction of the emerging TDD in GaSb buffer layers grown on Si(001) substrates by molecular beam epitaxy. the impact of the thickness, composition, and number of the insertion layers is extensively explored. Then a detailed study of the annealing cycles with different conditions is conducted. A record TDD in the low 107 cm−2 for a 2.25 µm GaSb buffer grown on Si(001) is ultimately demonstrated.

We demonstrate the heterogeneous integration of GaInAsSb–GaSb photodiodes on 220 nm SOI photonic integrated circuits (PICs) using the micro-transfer-printing (μTP) technology, for operation in the short-wave infrared (SWIR) wavelength region. Utilizing an evanescent coupling scheme between a silicon waveguide and a III–V structure, the device exhibits a room temperature responsivity of 1.23 and 1.25 A/W at 2.3 and 2.45 μm, respectively. This enables the realization of photonic integrated circuits for SWIR applications.

The high-speed parameters of an interband cascade laser grown on silicon are analyzed through the prism of relative intensity noise. The evolution of the relaxation frequency allows deriving a modulation bandwidth in the GHz range.