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Near infrared light detection is fundamental for sensing in various application fields. In this paper, we detail the properties of InGaAs/AlGaAs multiple quantum well (MQW) photodetectors (PDs) monolithically integrated by direct epitaxy on 300 mm Si(001) substrates. A MQW high crystalline quality is achieved using 300 mm Ge/Si pseudo-substrates with a low threading dislocation density of 4 × 107 cm−2 from electron channeling contrast imaging measurements. The localized states in the MQW stack are investigated using temperature-dependent photoluminescence. Two non-radiative recombination channels are identified. The first one is due to delocalized excitons generated by potential’s fluctuations because of the InGaAs/AlGaAs interfacial roughness (with an activation energy below 4 meV). The second one is due to exciton quenching because of the presence of numerous threading dislocations. A low dark current density of 2.5 × 10−5 A/cm2 is measured for PDs on Ge/Si substrates, i.e., a value very close to that of the same PDs grown directly on GaAs(001) substrates. A responsivity of 36 mA/W is otherwise measured for the photodiode on Ge/Si at room temperature and at −2 V.

On-chip avalanche photodetectors (APDs) are attractive for a sensitive detection of high-speed data light signals with low intensities. Silicon-germanium (Si-Ge) APDs are leading candidates to build reliable short-reach optical links. Appeal for Si-Ge APDs stems from larger (lower) gain-bandwidth (excess noise) at reduced voltages, CMOS-compliant production, and monolithic integration compared to their III-V alternatives [1] - [5] . Typically, Si-Ge APDs are metal-semiconductor-metal (MSM) [3] , separate absorption charge multiplication (SACM) [4] , or p-i-n [5] devices - each of them having their own advantages and drawbacks [1] . Although many Si-Ge APDs have appealing performances on their own, they are usually operated with other electronic components such as amplification stages, impeding low power consumption and low-cost detection on Si chips.

We present our latest advances in the development of compact photodetectors based on p-i-n silicon-germanium-silicon hetero-structures. We demonstrate credible high-speed performances, showing that those devices are likely to become key building blocks in next-generation photonic interconnects.

The demonstration of a germanium-based photodiode with a 3 dB bandwidth of 265 GHz and compatibility with silicon photonics and CMOS fabrication offers a cost-effective route to faster channel data rates for optical communications.

Integrated silicon nanophotonics has progressed a lot over past decades with great promises for many surging applications in optoelectronics, information and communication technologies, sensing or health monitoring. Enabling low-cost, dense integration, and compatibility with modern semiconductor nanofabrication processes, silicon nanophotonics deliver compact and high-performance devices on single chips. A variety of nanophotonic functionalities, both passive and active, are nowadays available on semiconductor substrates, leveraging the maturity of open-access silicon foundries and epitaxial germanium integration. It encompasses essential functions such as light generation and amplification, fast electro-optical modulation, and reliable conversion of optical into electrical signals. Germaniumbased optical photodetectors are main building blocks within the library of integrated silicon nanophotonics, with performances that are nowadays on par with their III-V-based counterparts. Germanium photodetectors integrated at the end of waveguides are attractive for next-generation on-chip interconnections, because of their compactness, bandwidth and speed, energy consumption and cost. In this work, we present our latest advances on silicon-germanium p-i-n waveguide-integrated photodetectors based on lateral silicon-germanium-silicon heterojunctions. Our hetero-structured photodetectors were fabricated on top of 200-mm silicon-on-insulator substrates using industrial-scale fabrication processes compatible with complementary metal-oxide-semiconductor technology. Silicon-germanium p-i-n photodetectors operated under low bias voltages exhibited low dark-currents (~100 nA), cut-off frequencies beyond 50 GHz, and photo-responsivities of about 1.2 A/W. Photodetector sensitivities of -14 dBm and -11 dBm were achieved for communication data rates of 10 Gbps and 25 Gbps, respectively. P-i-n photodetectors with lateral heterojunction operated in an avalanche regime offered an additional degree of freedom to improve device performances. High-speed and low-noise characteristics were obtained in our p-i-n photodetectors upon avalanche operation, with a gain-bandwidth product of 210 GHz and a low carrier impact ionization ratio of about 0.25. The measured sensitivity of avalancheoperated devices was -11 dBm for 40 Gbps signal detection. As demonstrated in the reported achievements, heterostructured p-i-n photodetectors are thus suitable communication devices in future intra-data center links or high-speed optical interconnects.

Optical photodetectors are at the forefront of photonic research since the rise of integrated optics. Photodetectors are fundamental building blocks for chip-scale optoelectronics, enabling conversion of light into an electrical signal. Such devices play a key role in many surging applications from communication and computation to sensing, biomedicine and health monitoring, to name a few. However, chip integration of optical photodetectors with improved performances is an on-going challenge for mainstream optical communications at near-infrared wavelengths. Here, we present recent advances in heterostructured silicon-germanium-silicon p-i-n photodetectors, enabling high-speed detection on a foundry-compatible monolithic platform.

Integrated silicon nanophotonics has rapidly established itself as intriguing research field, whose outlets impact numerous facets of daily life. Indeed, nanophotonics has propelled many advances in optoelectronics, information and communication technologies, sensing and energy, to name a few. Silicon nanophotonics aims to deliver compact and high-performance components based on semiconductor chips leveraging mature fabrication routines already developed within the modern microelectronics. However, the silicon indirect bandgap, the centrosymmetric nature of its lattice and its wide transparency window across optical telecommunication wavebands hamper the realization of essential functionalities, including efficient light generation/amplification, fast electro-optical modulation, and reliable photodetection. Germanium, a well-established complement material in silicon chip industry, has a quasi-direct energy band structure in this wavelength domain. Germanium and its alloys are thus the most suitable candidates for active functions, i.e. bringing them to close to the silicon family of nanophotonic devices. Along with recent advances in silicon–germanium-based lasers and modulators, short-wave-infrared receivers are also key photonic chip elements to tackle cost, speed and energy consumption challenges of exponentially growing data traffics within next-generation systems and networks. Herein, we provide a detailed overview on the latest development in nanophotonic receivers based on silicon and germanium, including material processing, integration and diversity of device designs and arrangements. Our Review also emphasizes surging applications in optoelectronics and communications and concludes with challenges and perspectives potentially encountered in the foreseeable future.

In this paper, we present a statistical characterization results for a high-speed germanium photo-detector structure that calls for no additional process steps than a regular modulator. The photodiodes in question are waveguide PIN SiGeSi photodiodes with targeted bandwidths on the range of 50GHz and a responsivity of more than 0.8A/W at 1310nm. The design logic, mainly intended to reduce the transit time while conserving a high detection area will be explained in details.

As the use of nanoparticles is expanding in many industrial sectors, pharmaceuticals, cosmetics among others, flow-through characterization techniques are often required for in-line metrology. Among the parameters of interest, the concentration and mass of nanoparticles can be informative for yield, aggregates formation or even compliance with regulation. The Suspended Nanochannel Resonator (SNR) can offer mass resolution down to the attogram scale precision in a flow-through format. However, since the readout has been based on the optical lever, operating more than a single resonator at a time has been challenging. Here we present a new architecture of SNR devices with piezoresistive sensors that allows simultaneous readout from multiple resonators. To enable this architecture, we push the limits of nanofabrication to create implanted piezoresistors of nanoscale thickness (∼100 nm) and implement an algorithm for designing SNRs with dimensions optimized for maintaining attogram scale precision. Using 8-in. processing technology, we fabricate parallel array SNR devices which contain ten resonators. While maintaining a precision similar to that of the optical lever, we demonstrate a throughput of 40 »000 particles per hour - an order of magnitude improvement over a single device with an analogous flow rate. Finally, we show the capability of the SNR array device for measuring polydisperse solutions of gold particles ranging from 20 to 80 nm in diameter. We envision that SNR array devices will open up new possibilities for nanoscale metrology by measuring not only synthetic but also biological nanoparticles such as exosomes and viruses.

International audience; Lately, germanium based materials attract a lot of interest as they can overcome some limits inherent to standard Silicon Photonics devices and can be used notably in Mid-Infra-Red sensing applications. The quality of epitaxially grown intrinsic and doped materials is critical to reach the targeted performances. One of the main challenges in the field remains the fabrication of efficient group-IV laser sources compatible with the microelectronics industry, seen as an alternative to the complexity of integration of III-V lasers on Si. The difficulties come from the fact that the group-IV semiconductor bandgap has to be transformed from indirect to direct, using high tensile strains or by alloying germanium with tin. Here, we review recent progresses on critical germanium-based photonic components such as waveguides, photodiodes and modulators and discuss the latest advances towards germanium-based lasers. We show that novel optical germanium-On-Insulator (GeOI) substrates fabricated by the Smart Cut™ technology is a key feature for future Si - Complementary Metal Oxide Semiconductor (CMOS) - compatible laser demonstration. This review hints at a future photonics platform based on germanium and Silicon.

Vertical GaAs p–i–n photodetectors epitaxially grown on GaAs(001), Ge/Si(001), and Si(001) substrates are reported. The performances of such photodetectors were investigated as a function of threading dislocation density in the stacks. A low dark current at room temperature, below 100 pA up to −9 V for all photodetectors, was evidenced. The absorption coefficients of GaAs were extracted from the spectral response of those p–i–n structures between 400 nm and 1100 nm. A responsivity of 0.17 A/W at 850 nm was obtained for a GaAs p–i–n structure grown directly on Si as compared to the value of 0.23 A/W obtained for the GaAs substrate. Such responsivity shows that III–V integration on Si is an efficient way of fabricating high performance optical sensors with low cost large scale productivity.

International audience; Hetero-structured silicon-germanium-silicon photodetectors operating under low-reverse-voltages with high responsivity, fast response, and low dark-current levels are reported. A bit-error-rate of 10-9 is experimentally achieved for conventional data rates of 10, 20, and 25 Gbps, providing optical power sensitivities of-13.9,-12.7, and-11.3 dBm.

International audience; Near-infrared germanium (Ge) photodetectors monolithically integrated on top of silicon-on-insulator substrates are universally regarded as key enablers towards chip-scale nanophotonics, with applications ranging from sensing and health monitoring to object recognition and optical communications. In this work, we report on the highdata-rate performance pin waveguide photodetectors made of a lateral hetero-structured silicon-Ge-silicon (Si-Ge-Si) junction operating under low reverse bias at 1.55 mu m. The pin photodetector integration scheme considerably eases device manufacturing and is fully compatible with complementary metal-oxide-semiconductor technology. In particular, the hetero-structured Si-Ge-Si photodetectors show efficiency-bandwidth products of similar to 9 GHz at -1 V and similar to 30 GHz at -3 V, with a leakage dark current as low as similar to 150 nA, allowing superior signal detection of high-speed data traffic. A bit-error rate of 10(-9) is achieved for conventional 10 Gbps, 20 Gbps, and 25 Gbps data rates, yielding optical power sensitivities of -13.85 dBm, -12.70 dBm, and -11.25 dBm, respectively. This demonstration opens up new horizons towards cost-effective Ge pin waveguide photodetectors that combine fast device operation at low voltages with standard semiconductor fabrication processes, as desired for reliable on-chip architectures in next-generation nanophotonics integrated circuits.

International audience; A new Si/Ge/Si heterojunction based waveguide photodetector has been demonstrated in order to reduce the fabrication cost, increase the responsivity, and improve process robustness. State of the art characteristics in terms of dark current, responsivity and bandwidth have been obtained. Furthermore, such photodetectors were characterized in avalanche mode in order to improve the sensitivity and reduce the overall power consumption of the optical circuit

Silicon photonics has generated in recent years a strong interest for a large range of applications from optical telecommunications to microelectronics. The main advantages of this technology are the reduction of photonic system costs and the increase of the number of functionalities on the same chip, notably by combining photonics and electronics. Numerous advances in silicon photonics have occurred, with the demonstration of high speed Si modulators, Ge photodetectors and hybrid laser on silicon [1]. The photodetector is one of the main building blocks for the implementation of fast silicon photonics integrated circuits. The required considerations for the design of such a device are the bandwidth, the power consumption and the responsivity. Germanium is now considered as the ideal candidate for fully integrated receivers on SOI substrates and based on CMOS-like processes. High speed and high responsivity Ge photodetectors have already reported on literature [2-4]. However, they suffer from relatively high dark currents as compared to their III-V homologues. The increase of bias voltage directly leads to higher bandwidth but also to a higher dark current mainly through tunneling, as a consequence of Ge low band-gap. Furthermore, Ge on Si suffers from crystal defects due to the lattice mismatch between Si and Ge. In this paper, we report on lateral pin photodiodes with thick Ge layers as the active media. Germanium is then integrated at the end of the Si waveguide, using the butt-coupling configuration to totally absorb light after few microns propagation at wavelength ranging from 1.3µm to 1.55µm (fig.1). Reliable detection characteristics have been obtained, including a bandwidth over 50GHz under zero-bias (fig.1), an internal responsivity higher than 0.5A/W at a wavelength of 1.55 µm and a dark current of about 10nA under -1V. 40Gb/s open eye diagrams were also obtained under zero-bias, showing the possibility of fabricating Ge-based low power and ultra-fast receivers. Some recent demonstrations of multiple-wavelength circuits and 40Gbit/s optical link, fabricated on a 300-mm microelectronics pilot line will also be presented {4]. Fig. 1: Schematic view of lateral Ge photodetector integrated in Si waveguide. SEM view of Ge photodetector cross-section.Normalized optical response as a function of frequency for lateral pin Ge photodiode under zero-bias. References: [1] L. Vivien and L. Pavesi, Handbook of silicon photonics, CRC & Taylor Press (2013) [2] L. Vivien et al., Opt. Express 20, 1096-1101 (2012). [3] C.T. DeRose et al., Opt. Express 19(25), 24897-24904 (2011). [4] S. Liao et al., Opt. Express 19(11), 10967-10972 (2011). [5] D. Marris-Morini et al., Opt. Express 22, 6674-6679 (2014)

International audience; This paper reports hollow MEMS plate oscillators for the characterization of liquid samples, with a one-fold improvement in both Q-factor and Allan deviation compared to previous alike structures, and fluidic constriction larger than 1μm. These new characteristics make the devices amenable for the first time to liquid weighing with a 100 Hz.(g.L-1)-1 sensitivity and a few g.L-1 detection floor.

Silicon photonics is becoming a technology of choice for optical communications. Compatibility with cmos manufacturing process is one key of success since it allows taking advantage of the production capacities of foundries; i.e. big volume and low cost manufacturability [1]. Germanium is the ideal candidate to build the integrated high performance photodiodes needed for receiver circuits [2]. Meanwhile, pure Ge epitaxy is not common in cmos processes and its integration within a silicon platform is not straightforward. In particular, germanium is very sensitive to wet etch processes. Post Ge-epitaxy dopant activation is also difficult due to thermal budget limitations. In this work, we propose a novel photodetector architecture which is integrated in a silicon photonic platform in a cost effective and robust manner.

International audience; Silicon is the mainstream material in the electronic industry and it is rapidly expanding its dominance into the field of photonics. Indeed, silicon photonics has been the subject of intense research activities to pave the way for next generation of energy-efficient high-speed computing, information processing and communications systems. The trend is to use optics in intimate proximity to the electronic circuit, which implies a high level of optoelectronic integration. Over the last decade, the field of silicon photonics has advanced at a remarkable pace. Recent advances in integrated germanium receiver will be presented including the developments of a new Ge-based detector integration and avalanche Ge structures.

Silicon photonics research can be dated back to the 1980s. However, the previous decade has witnessed an explosive growth in the field. Silicon photonics is a disruptive technology that is poised to revolutionize a number of application areas, for example, data centers, high-performance computing and sensing. The key driving force behind silicon photonics is the ability to use CMOS-like fabrication resulting in high-volume production at low cost. This is a key enabling factor for bringing photonics to a range of technology areas where the costs of implementation using traditional photonic elements such as those used for the telecommunications industry would be prohibitive. Silicon does however have a number of shortcomings as a photonic material. In its basic form it is not an ideal material in which to produce light sources, optical modulators or photodetectors for example. A wealth of research effort from both academia and industry in recent years has fueled the demonstration of multiple solutions to these and other problems, and as time progresses new approaches are increasingly being conceived. It is clear that silicon photonics has a bright future. However, with a growing number of approaches available, what will the silicon photonic integrated circuit of the future look like? This roadmap on silicon photonics delves into the different technology and application areas of the field giving an insight into the state-of-the-art as well as current and future challenges faced by researchers worldwide. Contributions authored by experts from both industry and academia provide an overview and outlook for the silicon waveguide platform, optical sources, optical modulators, photodetectors, integration approaches, packaging, applications of silicon photonics and approaches required to satisfy applications at mid-infrared wavelengths. Advances in science and technology required to meet challenges faced by the field in each of these areas are also addressed together with predictions of where the field is destined to reach.

Silicon-based photonics has generated a strong interest in the last years, mainly for optical telecommunications and optical interconnects in microelectronic circuits and industrial breakthroughs have been even performed by companies like IBM, Luxtera, INTEL, and ST Microelectronics. The main future rationales are the reduction of photonic system costs, the increase of the number of functionalities on the same integrated chip by combining photonics and electronics, and the decrease of power consumption. During the DACINCT workshop, we will present recent results on ultrafast optical modulators based on carrier depletion effect and germanium photodetectors integrated in silicon on insulator (SOI) waveguides. Both optoelectronic devices have been fabricated on a CMOS 300mm platform. The achieved performances constitute a new milestone towards new generations of several Tb/s chips merging electronics and photonics.

Silicon photonics integrated circuits development considerably spread in the last past years, and telecommunications and datacom applications are now clearly seen as its targets. With the increasing need of data rates, Si photonics components will have to offer very high speed as well as very low power consumption at lowest costs. The recent developments in photodetection have led to high speed and high responsivity waveguide integrated Ge photodetectors [1-3], with various configurations: butt coupling vs. evanescent coupling, vertical vs. lateral PIN junction. Nevertheless, Germanium absorption beyond 1550nm is limited, and long devices are needed, thus prohibiting Ge based photodiode use in the L-band (1565-1625) used in tele-communication. In this paper, we report on our latest development on very low dark current and high speed lateral PIN germanium photodetectors integrated with Si waveguides fabricated on 200mm and 300mm wafer size, for telecom and datacom applications .

Recent advances in silicon photonics have aided the development of on-chip communications. Power consumption, however, remains an issue in almost all integrated devices. Here, we report a 10 Gbit per second waveguide avalanche germanium photodiode under low reverse bias. The avalanche photodiode scheme requires only simple technological steps that are fully compatible with complementary metal oxide semiconductor processes and do not need nanometre accuracy and/or complex epitaxial growth schemes. An intrinsic gain higher than 20 was demonstrated under a bias voltage as low as -7 V. The Q-factor relating to the signal-to-noise ratio at 10 Gbit per second was maintained over 20 dB without the use of a trans-impedance amplifier for an input optical power lower than -26 dBm thanks to an aggressive shrinkage of the germanium multiplication region. A maximum gain over 140 was also obtained for optical powers below -35 dBm. These results pave the way for low-power-consumption on-chip communication applications.

We demonstrate the feasibility of producing advanced silicon photonic devices for future data communication nodes at 40Gbps using CMOS compatible processes in a 300mm wafer fab. Basic building blocks are shown together with various wavelength division multiplexing solutions. All the devices presented are integrated on 220nm SOI or locally grown epitaxial germanium.

Development of fast silicon photonics integrated circuit is mainly driven by the reduction of the power consumption. As a result, photodetectors with high efficiency, high speed and low dark current are needed to reduce the global link consumption. Germanium is now considered as the ideal candidate for fully integrated receivers based on SOI substrate and CMOS-like processes. We report on low power and high speed waveguide-integrated Ge photodetectors. Butt coupled lateral PIN structure photodiodes have been fabricated by Germanium selective growth and ion implantation at the end of silicon waveguide. Three types of photodiodes are reported, with dark current as low as 6nA at 1V reverse bias, optical bandwidth over 40GHz at zero bias and responsivity up to 0.8A/W at a wavelength of 1550nm. Such devices are suitable for data rate over 40Gbps and can be easily integrated with other photonic devices to fabricate wafer scale integrated circuits for datacom and telecom applications.

A new Optical-High-Frequency test structure and dedicated test bench have been developed to characterize a Germanium-on-Silicon photodiode intended to be used as an integrated noise source, a first step to high frequency transistor noise figure on-wafer extraction. Continuous wave signals have been measured from these 1550 nm photodiodes, with RF power higher than -20 dBm at 109 GHz.

Under the FP7 HELIOS project a 16 channel 10G transceiver based on a separate integrated transmitter incorporating hybrid lasers and modulators on silicon and a separate receiver both for 1550nm wavelength range has been demonstrated. An MZM (ITLMZ) chip consisting of a single mode hybrid III-V/silicon laser, a silicon Mach-Zehnder (MZ) modulator and an optical output coupler exhibited 10G operation with high BER. A 200GHz 16 channel receiver with polarization management was obtained with a 2D grating coupler, 2xAWGs and 16 Ge photodiodes. Polarization Dispersion Loss (PDL) was below 1dB, Bandwidth (BW) above 20GHz, receiver sensitivity in the order of 0.08 A/W

Silicon photonics has generated an outstanding interest for optical communications in electronic systems. This papers reviews recent results of advanced high performance generic building blocks that can be used for a broad range of applications requiring up to 40Gb/s. Described building blocks are waveguides, laser sources by III–V/Si heterogeneous integration, fast silicon modulators and germanium photodetectors.

A 200GHz 16 channel receiver with polarization management was obtained with a 2D grating coupler, 2xAWGs and 16 Ge photodiodes. PDL was below 1dB, BW above 20GHz, receiver sensitivity in the order of 0.08 A/W.

We report a Germanium lateral pin photodiode integrated with selective epitaxy at the end of silicon waveguide. A very high optical bandwidth estimated at 120GHz is shown, with internal responsivity as high as 0.8A/W at 1550nm wavelength. Open eye diagram at 40Gb/s was obtained under zero-bias at wavelength of 1.55μm.

40Gbit/s optical modulators based on carrier depletion effect and germanium photodetectors integrated in silicon waveguides have been demonstrated at a wavelength of 1.55µm.

International audience; For the sub-32 nm node, porous SiCOH dielectrics (p-SiCOH) are integrated using dual damascene patterning by etching trenches and vias into the porous material. One challenge is to control the process conditions to minimize the plasma-induced damage of p-SiCOH materials at the bottom and at the sidewall of the trenches. Ellipsometric Porosimetry has been adapted to characterize the plasma-treated materials for both horizontal and vertical surfaces. Since surface modifications can cause adsorption and desorption delays and hydrophobicity loss, porosimetry measurements operated with multi-solvent and kinetic protocols are required. Quantitative measurements of vertically patterned materials are demonstrated using periodic structures of porous material and a Scatterometric Porosimetry analysis. Results show a good sensitivity of the measurement to the different process conditions but also highlight a different impact of the plasma processes on patterned materials compared with blanket films.

We demonstrated 40 Gbit/s optical link by coupling a silicon (Si) optical modulator to a germanium (Ge) photo-detector from two separate photonic chips. The optical modulator was based on carrier depletion in a pn diode integrated in a 950-µm long Mach-Zehnder interferometer. The Ge photo-detector was a lateral pin diode butt coupled to a silicon waveguide. The overall loss, which is mainly due to coupling (3 grating couplers times ~4 dB) was estimated to be lower than 18 dB. That also included modulator loss (4.9-dB) and propagation loss (1 dB/cm). Both optoelectronic devices have been fabricated on a 300-mm CMOS platform to address high volume production markets.

We investigate the most appropriate way to optically characterize the materials and predict the spectral responses of metal-dielectric filters in the visible range. Special attention is given to thin silver layers that have a major impact on the filter's spectral transmittance and reflectance. Two characterization approaches are compared, based either on single layers, or on multilayer stacks, in approaching the filter design. The second approach is preferred, because it gives the best way to predict filter characteristics. Meanwhile, it provides a stack model and dispersion relations that can be used for filter design optimization.

This paper reports on high-performance waveguide-integrated germanium photodiodes for optical communications applications. 200 mm wafers and production tools were used to fabricate the devices. Yields over 97% were obtained for three different compact photodiodes (10×10 μm and intrinsic region width of 0.5, 0.7, and 1 μm) within the same batch of three wafers. Those photodiodes exhibit low dark currents under reverse bias with median values of 74, 62, and 61 nA for intrinsic widths of 0.5, 0.7, and 1 μm, respectively, over a full wafer. Responsivities up to 0.78 A/W at 1550 nm and zero bias were measured. Zero bias operation is possible for 25 and 40 Gbps with receiver sensitivity estimated to −13.9 and −12.3 dBm, respectively.

40Gbit/s optical modulators based on carrier depletion effect and germanium photodetectors integrated in silicon waveguides have been demonstrated at a wavelength of 1.55µm.

We report performances of active and passive devices in a Silicon-Photonic library on a 300mm-CMOS-platform, showing highly uniform behavior of passive WDM devices, Mach-Zehnder modulators and germanium photo-detectors with state of the art performances.

This paper reports on high speed Ge photodetectors integrated in Si waveguides which present very low dark current (25nA @-1V). 40Gbit/s operation under zero bias was reported at a wavelength of 1.55μm.

International audience; On-chip light detection is universally regarded as a key functionality that enables myriad of applications, including optical communications, sensing, health monitoring or object recognition, to name a few. Silicon is widely used in the microelectronics industry. However, its electronics bandgap precludes the fabrication of high-performance photodetectors that operate at wavelengths longer that 1.1 µm, a spectral range harnessed by optical communication windows of low fiber attenuation and dispersion. Conversely, Germanium, a group-IV semiconductor as Silicon, with a cutoff wavelength of ~1.8 µm, yields efficient light detection at near-infrared wavelengths. Germanium-based photodetectors are mature building blocks in the library of silicon nanophotonic devices, with a low dark-current, a fast response, a high responsivity and low power consumption with an established fabrication flow. In this work, we report on the design, fabrication and operation of waveguide pin photodetectors that advantageously exploit lateral Silicon/Germanium/Silicon heterojunctions. Devices were fabricated on 200 mm silicon-on-insulator substrates using standard microelectronics production tools and processes. This photodetector architecture takes advantage of the compatibility with contact process steps of silicon modulators, thereby offering substantially reduced fabrication complexity for transmitters and receivers, while providing improved optical characteristics. More specifically, at a low-bias reverse voltage of-1 V, we experimentally achieved dark-currents lower that 10 nA, a device photo-responsivity up to 1.1 A/W, and large 3-dB opto-electrical bandwidths over 50 GHz. In addition, high-speed data rate transmission measurements via eye diagram inspection have been conducted, with pin photodetector operation at the conventional 10 Gbps up to the future 40 Gbps link speeds.

Photodetectors are cornerstone components in integrated optical circuits and are essential for applications underlying modern science and engineering. Structures harnessing conventional crystalline materials are typically at the heart of such devices. In particular, group-IV semiconductors such as silicon and germanium open up more possibilities for high-performing on-chip photodetection thanks to their favorable electrical and optical properties at near-infrared wavelengths and processing compatibility with modern chip manufacturing. However, scaling the performance of silicon-germanium photodetectors to technologically relevant levels and benefiting from improved speed, reduced driving bias, enhanced sensitivity, and lowered power consumption arguably remains key for densely integrated photonic links in mainstream shortwave infrared optical communications. Here we report on a reliable 40 Gbps direct detection of chip-integrated silicon-germanium avalanche p-i-n photo receiver driven with low-bias supplies at 1.55 µm wavelength. The avalanche photodetection scheme calls upon fabrication steps commonly used in complementary metal-oxide-semiconductor foundries, alleviating the need for complex epitaxial wafer structures and/or multiple ion implantation schemes. The photo receiver exhibits an internal multiplication gain of 120, a high gain-bandwidth product up to 210 GHz, and a low effective ionization coefficient of ∼ 0.25 . Robust and stable photodetection at 40 Gbps of on–off keying modulation is achieved at low optical input powers, without any need for receiver electronic stages. Simultaneously, compact avalanche p-i-n photodetectors with submicrometric heterostructures promote error-free operation at transmission bit rates of 32 Gbps and 40 Gbps, with power sensitivities of − 12.8 d B m and − 11.2 d B m , respectively (for 10 − 9 error rate and without error correction coding during use). Such a performance in an on-chip avalanche photodetector is a significant step toward large-scale integrated optoelectronic systems. These achievements are promising for use in data center networks, optical interconnects, or quantum information technologies.