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The introduction of selective area growth (SAG) in a mature semi‐insulating buried heterostructure (SIBH) platform for the realization of photonic integrated circuits on monolithic InP has been demonstrated. A thorough determination of the relations between quantum well thickness, transition energies, and mask geometries is performed on dedicated wafers by means of extensive micro‐X‐Ray diffraction and microphotoluminescence measurements. Based on those results, SAG is used to grow, with a single epitaxy step, AlGaInAs multiple quantum wells heterostructures, to tailor the active regions of Fabry–Pérot and distributed feedback (DFB) lasers emitting in the O‐Band. SIBH DFB lasers are realized, exhibiting threshold currents < 7.2 mA (at 25 °C), and emitting over 100‐nm spectral range in the O‐Band. [ABSTRACT FROM AUTHOR]

The integration of III-V multi-junction solar cells on Si substrates is currently one of the most promising possibilities to combine high photovoltaic performance with a reduction of the manufacturing costs. In this work, we propose a prospective study for the realization of an InP/InGaAs tandem solar cell lattice-matched to InP on a commercially available Si template by direct MOVPE growth. The InP top cell and the InGaAs bottom cell were firstly separately grown and optimized using InP substrates, which exhibited conversion efficiencies of 13.5% and 11.4%, respectively. The two devices were then combined in a tandem device by introducing an intermediate InP/AlInAs lattice-matched tunnel junction, showing an efficiency of 18.4%. As an intermediate step towards the realization of the tandem device on Si, the InP and InGaAs single junction solar cells were grown on top of a commercial InP/GaP/Si template. This transitional stage enabled to isolate and evaluate the effects of the growth of III-V on Si on the photovoltaic performance through the comparison with the aforementioned devices on InP. Each cell was electrically characterized by external quantum efficiency and dark and illuminated current-voltage under solar simulator. The material quality was also analyzed by means of X-ray diffraction, Atomic-Force Microscopy, Transmission Electron and Scanning Electron Microscopy. The III-V on Si devices showed efficiencies of 3.6% and 2.0% for the InP and InGaAs solar cells, respectively. [ABSTRACT FROM AUTHOR]

Solar cells are complex devices, being constituted of many layers and interfaces. The study and the comprehension of the mechanisms that take place at the interfaces is crucial for efficiency improvement. This paper applies Kelvin probe force microscopy (KPFM) to study materials and interfaces with nanometer scale imaging of the surface potential in the dark and under illumination. KPFM measurements are highly sensitive to surface states and to the experimental measurement environment influencing the atomic probe operating conditions. Therefore, in order to develop a quantitative understanding of KPFM measurements, we have prepared a dedicated structured sample with alternating layers of InP:S and InP:Fe whose doping densities were determined by secondary-ion mass spectroscopy. We have performed KPFM measurements and shown that we can spatially resolve 20 nm thick InP layers, notably when performed under illumination which is well-known to reduce the surface band-bending. [ABSTRACT FROM AUTHOR]

Featured Application: Compact lasers integrated onto SOI for optical communications. The tremendous demand for low-cost, low-consumption and high-capacity optical transmitters in data centers challenges the current InP-photonics platform. The use of silicon (Si) photonics platform to fabricate photonic integrated circuits (PICs) is a promising approach for low-cost large-scale fabrication considering the CMOS-technology maturity and scalability. However, Si itself cannot provide an efficient emitting light source due to its indirect bandgap. Therefore, the integration of III-V semiconductors on Si wafers allows us to benefit from the III-V emitting properties combined with benefits offered by the Si photonics platform. Direct epitaxy of InP-based materials on 300 mm Si wafers is the most promising approach to reduce the costs. However, the differences between InP and Si in terms of lattice mismatch, thermal coefficients and polarity inducing defects are challenging issues to overcome. III-V/Si hetero-integration platform by wafer-bonding is the most mature integration scheme. However, no additional epitaxial regrowth steps are implemented after the bonding step. Considering the much larger epitaxial toolkit available in the conventional monolithic InP platform, where several epitaxial steps are often implemented, this represents a significant limitation. In this paper, we review an advanced integration scheme of AlGaInAs-based laser sources on Si wafers by bonding a thin InP seed on which further regrowth steps are implemented. A 3 µm-thick AlGaInAs-based MutiQuantum Wells (MQW) laser structure was grown onto on InP-SiO2/Si (InPoSi) wafer and compared to the same structure grown on InP wafer as a reference. The 400 ppm thermal strain on the structure grown on InPoSi, induced by the difference of coefficient of thermal expansion between InP and Si, was assessed at growth temperature. We also showed that this structure demonstrates laser performance similar to the ones obtained for the same structure grown on InP. Therefore, no material degradation was observed in spite of the thermal strain. Then, we developed the Selective Area Growth (SAG) technique to grow multi-wavelength laser sources from a single growth step on InPoSi. A 155 nm-wide spectral range from 1515 nm to 1670 nm was achieved. Furthermore, an AlGaInAs MQW-based laser source was successfully grown on InP-SOI wafers and efficiently coupled to Si-photonic DBR cavities. Altogether, the regrowth on InP-SOI wafers holds great promises to combine the best from the III-V monolithic platform combined with the possibilities offered by the Si photonics circuitry via efficient light-coupling. [ABSTRACT FROM AUTHOR]

Featured Application: Compact on-chip widely tunable lasers and semiconductor optical amplifiers on heterogeneously integrated III-V/SOI platforms for optical communications. Heterogeneously integrated III-V/Si lasers and semiconductor optical amplifiers (SOAs) are key devices for integrated photonics applications requiring miniaturized on-chip light sources, such as in optical communications, sensing, or spectroscopy. In this work, we present a widely tunable laser co-integrated with a semiconductor optical amplifier in a heterogeneous platform that combines AlGaInAs multiple quantum wells (MQWs) and InP-based materials with silicon-on-insulator (SOI) wafers containing photonic integrated circuits. The co-integrated device is compact, has a total device footprint of 0.5 mm2, a lasing current threshold of 10 mA, a selectable wavelength tuning range of 50 nm centered at λ = 1549 nm, a fiber-coupled output power of 10 mW, and a laser linewidth of ν = 259 KHz. The SOA provides an on-chip gain of 18 dB/mm. The total power consumption of the co-integrated devices remains below 0.5 W even for the most power demanding lasing wavelengths. Apart from the above-mentioned applications, the co-integration of compact widely tunable III-V/Si lasers with on-chip SOAs provides a step forward towards the development of highly efficient, portable, and low power systems for wavelength division multiplexed passive optical networks (WDM-PONs). [ABSTRACT FROM AUTHOR]

We present a complete characterization of reflective electroabsorption modulators (EAMs) monolithically integrated with semiconductor optical amplifiers (SOAs), components that are capable of operating beyond 50 Gb/s in the C-band. The devices are based on GaInAsP multiple quantum wells on InP substrate, leveraging semi-insulating buried heterostructure waveguide definition and butt-joint integration technologies. Different device configurations, based on 80- and 150-μm long EAMs, are fabricated and characterized in both static and dynamic modes. The frequency response of the 80 μm long EAM is still flat at 26.5 GHz (setup upper limit) whereas the 150 μm long EAM exhibits a 3-dB cutoff bandwidth of 23 GHz. A zero-chirp is achieved for EAM reverse bias voltages between −1.2 and –1.5 V depending on the wavelength. Under large-signal modulation, the frequency chirp induced by the shorter EAM is almost half that of the longer EAM, with their respective peak values being +1.5/−2 and +3.2/−3.7 GHz (rising/falling edges) at 1545 nm (−1.3 V bias, 2.6 V voltage swing). We obtained high dynamic extinction ratios of ∼14.5 and ∼8 dB from the longer and the shorter EAMs, respectively, when they are operated at 25 Gb/s using non-return-to-zero coding. Finally, we achieved 12 and 16 km colorless transmissions in the C-band (between 1530 and 1545 nm) over a standard single-mode fiber without equalization using the 150- and the 80 μm EAMs, respectively, with 4.5 and 2.5 dB dispersion penalties at a bit error rate of 10–3. [ABSTRACT FROM AUTHOR]

In this work, we present the fabrication process of a $3~\mu \text{m}$ -thick AlGaInAs-based vertical p-i-n laser diode structure grown on a directly bonded InP-SiO2/Si (InPoSi) substrate. High-quality epitaxial growth on InPoSi is reported. Based on these structures, the fabrication process of Fabry-Perot broad lasers is presented. Device performance is compared to the ones obtained from the same growth run on an InP substrate as a reference. High electrical properties of the n and p contacts are demonstrated. Lasing operation in the pulse regime is shown up to 50°C. Threshold current densities as low as 0.4 kA/cm2 at 20°C are obtained for the laser on InPoSi, comparable to the ones obtained for the reference on InP substrate. [ABSTRACT FROM AUTHOR]

Heterogeneous integration of III-V materials onto silicon photonics has experienced enormous progress in the last few years, setting the groundwork for the implementation of complex on-chip optical systems that go beyond single device performance. Recent advances on the field are expected to impact the next generation of optical communications to attain low power, high efficiency and portable solutions. To accomplish this aim, intense research on hybrid lasers, modulators and photodetectors is being done to implement optical modules and photonic integrated networks with specifications that match the market demands. Similarly, important advances on packaging and thermal management of hybrid photonic integrated circuits (PICs) are currently in progress. In this paper, we report our latest results on hybrid III-V on Si transmitters, receivers and packaged optical modules for high-speed optical communications. In addition, a review of recent advances in this field will be provided for benchmarking purposes. [ABSTRACT FROM AUTHOR]

InP/InGaAs and InGaAs/InP interfaces in heterostructures grown by metalorganic vapor-phase epitaxy (MOVPE) have been studied by transmission electron microscopy (TEM). Cross-sectional TEM 002 dark field images of the direct (InP-InGaAs) and inverted (InGaAs-InP) interfaces revealed a great difference in abruptness. Whereas the direct interface is always well defined and flat, the inverted one is compositionally graded and shows surface undulations. InP--InGaAs heterostructures were studied for different layer thicknesses and phosphine flow rates. The results indicate that this effect originates more from the substitution of arsenic by phosphorus atoms in subsurface InGaAs monolayers rather than from As carryover to the InP layer. The strong As--P exchange observed over several InGaAs monolayers is related to the large difference in chemical bond strength between Ga--As and Ga--P. This is supported by comparison with InP/InA1As/InP and InP/In[SUB1-x]Ga[SUBx]As[SUBy]P[SUB1-y]/InP (0.1

The extension of a photonic integrated circuit foundry process flow is proposed by integrating selective area growth to enable bandgap tuning for each individual active building block. The process adaptations and the impact on performance are reviewed in terms of morphology requirements and topology reduction. This platform extension enables bandgap tuning for a set of active devices to cover the wavelength range from 1453 to 1651 nm. Integration is demonstrated in combination with active–passive butt-joint technology to create the most comprehensive range of generic building blocks. Performance and limitations of the range of achievable band edges within the same monolithic wafer are studied for amplifiers and extended cavity lasers. [ABSTRACT FROM AUTHOR]

Monolithic two‐terminal III‐V on Si dual‐junction solar cells, designed for low concentration applications, were fabricated by means of surface‐activated direct wafer bonding. The III‐V top cell is a heterojunction formed by an n‐Ga0.5In0.5P emitter and a p‐Al0.2Ga0.8As base. An efficiency of 21.1 ± 1.5% at one sun and 23.7 ± 1.7% at 10 suns is demonstrated, which to our knowledge is the best dual‐junction two‐terminal III‐V on Si tandem cell efficiency reported to date under verified reference conditions. The I‐V characterization of these 1‐cm2 tandem cells under concentration required the development of a new method using a single‐source multiflash solar simulator and not perfectly matched component cells, also known as pseudo‐isotypes, formed by Si single‐junction cells and optical filters. In addition, the spectrum of the pulsed solar simulator was measured using a high‐speed CMOS spectrometer, allowing the calculation of the spectral mismatch correction factor. Merging these two techniques results in the hybrid corrected pseudo‐isotype (HCPI) characterization method, which shows a fast and accurate performance with a simplified procedure based on a single‐source solar simulator. Pseudo‐isotypes are easily adaptable to new cell designs by simply using a different filter, hence allowing the characterization of new multijunction solar cell architectures. [ABSTRACT FROM AUTHOR]

Multijunction solar cells based on III–V compounds are one of the most effective possibilities to achieve high efficiencies for space and terrestrial applications. In this work, AlInAs:C/InP:S tunnel junctions are fabricated using MOVPE. Type‐II interface band alignment of AlInAs/InP heterostructure is ideal for increasing the photogenerated carriers tunneling. Furthermore, wide bandgaps ensure a high transmission of the incident light. The J–V characteristics of the final devices show very good results in terms of tunneling peak current density (1000 A cm−2) and specific resistance at low applied bias, making them compatible for photovoltaic applications. [ABSTRACT FROM AUTHOR]

We report on a fully integrated hybrid III-V on a silicon distributed feedback laser integrated with a ring resonator. We demonstrate an enhanced extinction ratio up to 5 dB at 25 Gb/s of the distributed feedback laser when the ring-resonator is finely tuned. We validated the transmitter with a 20-km transmission with only 2.5-dB penalty and 20-dB power budget. [ABSTRACT FROM AUTHOR]

Monolithic photonic integrated circuits (PIC) transmitters using the prefixed optical phase switching concept for BPSK modulation format have been shown promising at 1.55 μm band. These devices could also be crucial for short reach connections and access networks. With this aim, we are studying basic quantum well designs for a laser and an electro-absorption modulator switch to be integrated by selective area growth into PICs at 1.3 μm. Photocurrent measurements and band offset modeling have been performed to determine the MQW stack well-fitted for this application. Broad area laser measurements have also been checked on these structures to verify the material lasing properties. A 6 nm thick well with low barrier seems to be the best trade-off between absorption and shift for 1.3 μm EAM and it also gives good lasing properties. [ABSTRACT FROM AUTHOR]

We demonstrate a 56-GBd pulse-amplitude modulation-4 compact InP transmitter module integrating a distributed feedback laser and an electro-absorption modulator, which exhibits 50-GHz bandwidth, >13-dB extinction ratio and up to 1.5-mW output power. Successful amplifier-free 112-Gb/s transmission is performed over 2 km using low complexity three-taps equalization. We also study the tradeoff between receiver bandwidth, equalizer length and performance, and show successful signal recovery with bandwidths as low as 18 GHz when increasing the equalizer length. [ABSTRACT FROM PUBLISHER]

We report on the thermal design and the characterization of InP-based 1.55 μm wavelength large diameter (∼100 μm) optically pumped vertical external cavity surface emitting lasers (OP-VECSELs). The device is thermally optimized for high power ( > 70 mW) room-temperature (RT) continuous-wave (CW) single-mode operation. Efficient bottom heat dissipation in the 1/2-VCSEL chip is obtained thanks to the use of a hybrid metal– metamorphic GaAs/AlAs mirror integrated to the InP-based active region, and to subsequent soldering on a SiC substrate. A single-mode output power of 77mW is obtained under CW-RT laser operation, limited by the pump power. Moreover thermal simulations and characterizations of the 1/2-VCSEL chip show that even higher power could be obtained at higher pumping levels, using a CVD diamond substrate. [ABSTRACT FROM AUTHOR]

Presents information on a study which focused on the breakdown voltage of a triple channel high-electron mobility transistor (HEMT) structure on InP for large-signal high-speed applications. Structure of the multichannel Camel transistor; Device fabrication and experimental results; Conclusion.

Hybrid integration of III–V materials onto silicon by wafer bonding technique is one of the mature and promising approaches to develop advanced photonic integrated devices into the silicon photonics platform (SPP). Epitaxial regrowth of III–V materials on InP thin seed layer bonded to an oxidized silicon wafer has shown its potential to extend the III–V mature multiregrowth technologies into the SPP. In the approach, an epitaxial InP layer grown on a 4 in. InP wafer is directly bonded onto a SiO2/Si 200 mm wafer. After InP substrate removal, the new template (InPoSi) is evaluated for epitaxial regrowth: an eight periods strain‐compensated AlGaInAs multiquantum wells (MQW) heterostructure surrounded by two InP cladding layers is grown by metal‐organic vapor phase epitaxy (MOVPE) simultaneously on the InPoSi substrate and on an InP substrate as a reference. For the first time, in situ reflectance and curvature measurements are carried out on InPoSi, enabling the assessment of surface roughness and thermal strain of the III–V materials during growth. High material quality is obtained as attested by X‐ray diffraction, photoluminescence, atomic force microscopy, and transmission electron microscopy. [ABSTRACT FROM AUTHOR]

Several all-optical switching devices based on quantum well microcavity structures have been studied in view of their possible use for all-optical regeneration of telecommunication signals. Experiments and modeling show that the saturation energy is inversely proportional to a scaling factor describing the enhancement of the intracavity intensity at the Fabry-Perot resonance. As a result the saturation energy is approximately proportional to the number of quantum wells in the device and can be kept small by a proper cavity design. [ABSTRACT FROM AUTHOR]

The design, fabrication, and characterization of an amplifying transverse magnetic (TM)-mode optical waveguide isolator operating at a wavelength of 1300 nm are presented. The magneto-optical Kerr effect induces nonreciprocal modal absorption in a semiconductor optical amplifier with a laterally magnetized ferromagnetic metal contact. Current injection in the active structure compensates for the loss in the forward propagation direction. Monolithic integration of this optical isolator configuration with active InP-based photonic devices is straightforward. The combination of AlGaInAs/InP active material and the metal alloy Co50Fe50 results in greatly improved performance. 99 dB/cm TM mode isolation and significantly reduced insertion loss are demonstrated. [ABSTRACT FROM AUTHOR]

Short-wavelength infrared image sensors based on p-i-n photodiode arrays present a tremendous interest in applications such as passive and active imagery for laser detection/warning, hot spot or detection for lasers sensors, enhanced vision systems or low light level sensors. The capability to work at room temperature with dark current equivalent to silicon-based devices is another motivation for the fast development of this technology. This paper presents several modules and camera based on InGaAs photodiode arrays from the III-VLab. First, we describe the electro-optics performance in terms of dark signal, sensitivity, and particularly the visible extension capability. We also present a nucless logarithmic sensor based on a 1/2 video graphics array (VGA) format at a pitch of 25 μm initially designed for visible CMOS camera chip. We will also present the next generation of focal plane arrays based on a VGA format of 640×512 pixels with a pitch of 15 μm. This array will be associated to a CTIA readout circuit and also to an innovative CMOS logarithmic wide dynamic range ROIC, developed by New Imaging Technologies. This VGA logarithmic device developed for automotive safety will involve visible extension capability in a European project named 2Wide_sense. [ABSTRACT FROM AUTHOR]