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Silicon photonics (SiPh) has emerged as a photonic integrated circuit (PIC) platform, especially for high volume applications. Integrated laser sources, however, remain a challenge. SiPh foundries have existed for more than 10 years but still don’t offer a qualified process with integrated lasers. Direct heteroepitaxy of group III-V materials on silicon is still immature and suffers from reliability issues. Heterogeneous and hybrid integration techniques, however, have been pursued in research and by industry and present a practical near-term solution for laser integration. Heterogenous approaches based on wafer bonding involve the bonding of bare III-V epitaxial material to silicon on insulator (SOI), co-fabrication, and evanescent light coupling. The laser active medium is thermally isolated from the silicon substrate by the buried oxide layer limiting the laser efficiency at high temperature. Hybrid integration approaches, such as the butt coupling of fabricated III-V lasers to SOI waveguides, may address the thermal issue. However, the main limitation for butt coupling is the significant mode mismatch of the waveguides that imposes a strict alignment requirement.In this thesis the novel 3D hybrid integration technique for SiPh, addressing the aspects of thermal performance and alignment tolerance, was proposed and demonstrated for the first time. This approach is based on the flip-chip integration of indium phosphide (InP) reflective semiconductor optical amplifiers (RSOAs) containing total internal reflection turning mirrors for surface emission. Light is coupled to the SOI waveguides through surface grating couplers. This technique yields increased alignment tolerance compared to butt coupling. Flip-chip integration also allows the RSOA chip to be bonded P-side down directly to the silicon substrate. In this way, the heat generated in the active region can dissipate more efficiently in the silicon. 3D hybrid integration can be carried out at wafer level in a backend step for high throughput manufacturing, and also allow for the integration of InP PICs on silicon interposers for large-scale electronic-photonic integration.A tunable laser was demonstrated with 3D hybrid integration demonstrating a side-mode suppression ratio up to 43 dB. Greater than 4 mW of optical power was coupled into SiPh waveguide and more than 20 nm wavelength tuning range was achieved. A linewidth of 1.5 MHz and relative intensity noise of -132 dB/Hz were demonstrated. A low thermal impedance of 6.2 ℃/W was extracted experimentally from a 3D hybrid laser that was bonded to the silicon substrate, demonstrating a factor of three improvement over a laser that was bonded above the SOI layer. To improve coupling efficiency, various advanced silicon surface grating couplers as well as dilute waveguide RSOAs were investigated. Coupling efficiency up to 85\% can be achieved while also maintaining an alignment tolerant implementation.

This chapter reviews the status of heterogeneous integration of silicon waveguides and photodetectors. The most commonly used available fabrication technologies, namely germanium growth and III/V-silicon wafer bonding, are described. Design constraints common to both platforms, as well as the key differences between them, are discussed. An overview of demonstrated devices on both platforms is presented.

Recent research in the field of photovoltaic and solar cell fabrication has shown the potential to significantly enhance light absorption in thin-film solar cells by using surface texturing and nanostructure coating techniques. In this paper, for the first time, we propose a new method for nano sandwich type thin-film solar cell fabrication by combining the laser amorphization (2nd solar cell generation) and laser nanofibers generation (3rd solar cell generation) techniques. In this novel technique, the crystalline silicon is irradiated by megahertz frequency femtosecond laser pulses under ambient conditions and the multi-layer of amorphorized silicon and nano fibrous layer are generated in the single-step on top of the silicon substrate. Light spectroscopy results show significant enhancement of light absorption in the generated multi layers solar cells (Silicon Oxide nanofibers / thin-film amorphorized silicon). This method is single step and no additional materials are added and both layers of the amorphorized thinfilm silicon and three-dimensional (3D) silicon oxide nanofibrous structures are grown on top of the silicon substrate after laser irradiation. Finally, we suggest how to maximize the light trapping and optical absorption of the generated nanofibers/thin-film cells by optimizing the laser pulse duration.

In this study we report for the first time a method for direct patterning of silicon oxide on a silicon substrate by irradiation with a femtosecond laser of Mega Hertz pulse frequency under ambient condition. Embossed lines of silicon oxide with around 3~4 µm width and less than 100 nm height were formed by controlling the parameters such as laser pulse power and frequency rate. A Scanning Electron Microscope (SEM), an optical microscopy and a Micro-Raman and Energy Dispersive X-ray (EDX) spectroscopy were used to analyze the silicon oxide layer.

We demonstrate a hybrid silicon tunable laser with wide tunability and rapid switching speed for applications in sensing and optical networks. By implementing an optimized carrier injection phase shifter design, the filters of the silicon laser cavity may be efficiently controlled, enabling both fine and broad wavelength tuning across a 56 nm range, in addition to a rapid 10 ns switching time. The laser emits up to 10 dBm output power, and the linewidth is near 200 kHz. The fast wavelength switching demonstrated here may be employed in data center and access networks, while the potential for rapid wavelength sweeping is attractive for optical sensing and imaging applications.

We study the influence of the intra-cavity ring on dynamics, phase noise and timing jitter of a long-ring-cavity colliding pulse mode-locked laser using a delay differential equation (DDE) model. The results of dynamic show that the intra-cavity filter can suppress harmonics of 2 GHz cavity. We also find a reduction of phase noise and timing jitter compared to the fundamental 20 GHz ring laser, which is in good agreement with experimental result.

This chapter discusses in detail the physics behind the different silicon-based photodetector technologies. It analyses the challenges and perspectives of silicon-based photosensors with a brief overview of hybrid and three-dimensional (3D) sensor technology.

Owing to the introduction of wide-bandgap power devices, recent power modules operate at higher temperatures. This increased module temperature leads to significant reliability problems, which render thermal monitoring very important. Several thermal sensors have been used in power modules; however, each of these sensors has drawbacks such as limited maximum temperature, nonlinearity, power source requirement, or limited miniaturization. This paper proposes a new temperature sensor that utilizes the piezoelectric effect. A new piezoelectric material (PZT-PZNM) with a high Curie temperature (260 °C) is soldered onto a direct bonded copper substrate. When the power module is operating at a high temperature, the substrate deflects and induces thermal stress, which is converted into an electric voltage via a piezoelectric mechanism. The voltage can be maximized by optimizing the location of the PZT-PZNM; the best location was determined to be away from the power devices. This observation confirms that the piezoelectric temperature sensor has a negligible influence on the performance of the power devices. Moreover, the sensor volume was miniaturized (approximately 74% reduction compared with preliminary work) to ensure that it can be readily integrated into power modules. The developed piezoelectric sensor demonstrates excellent linearity ( R 2 = 0.99, approximately) up to 250 °C, which is sufficient for monitoring temperature in both silicon and silicon carbide power modules.

Future silicon wafers are getting thinner in semiconductor industry to satisfy the requirement of miniaturizing package size in mobile device applications. Development of thin wafers is the mutual goal of current semiconductor researches. In this paper, a novel method incorporating the convenience of laser ablation and speed of plasma etching is proposed to replace traditional mechanical dicing saw for thin wafer cutting. The main idea is to use laser to create patterns on the silicon wafer coated with water soluble protection material and the unprotected area is exposed to the high-density plasma which is later etched through. This study includes development of the water-soluble protecting mask material, design of inductively coupled plasma (ICP) and microwave plasma sources, pattern scribing utilizing ultrafast laser, and trial of an etching (Bosch) process associated with the high-density plasma chamber to create high aspect ratio trench. The polyvinyl alcohol (PVA) based protecting material has excellent solubility and is extremely easy to be rinsed by water. With appropriately added chemicals, optical absorption is improved for laser ablation. A 532 nm 10 pico-second laser is used to perform surface scribing with minimal recast and heat affected zone (HAZ) at the edges. Good plasma homogeneity is demonstrated in the designed 12″ microwave and ICP chambers. With the protection coating the silicon wafer can be etched at 7.2 µm/min rate and 10.11 etch selectivity by the microwave and ICP sources in the chamber. Finally, etching process trials are performed, and the results show that deep and high aspect ratio trenches (~15 µm wide, ~95 µm deep) can be achieved which is fully acceptable for wafers under 100 µm thickness.

In this work, we report a simple and efficient purification technique of solar grade silicon wafers suitable for high efficiency and low-cost silicon solar cells. This gettering method requires the elaboration of silicon nanowire thin layer followed by an annealing treatment and removing impurity loaded silicon nanowires. ICP-AES analysis shows a significant decrease in the metallic impurity concentration resulting considerable enhancement in the silicon purity grade. Electrical characterizations reveal a global decrease of the majority carrier concentration and a substantial improvement of the minority carrier lifetime. Furthermore, the application of this novel gettering process induces an enhancement in the silicon solar cell electrical parameters. These results give evidence of the effectiveness of the proposed purification method to produce efficient solar cells starting from low-quality silicon wafers.

This paper summarizes the recent advances of integrated hybrid InP/SOI lasers and transmitters based on edge coupling. First, we review the different integration methods between III–V material and silicon. Then, we focus on using an external III–V chip coupled via edge coupling to our silicon photonic integrated circuit. The paper reports on the results of wavelength tunable lasers containing one or two ring resonators as well as an integrated reflectivity tunable mirror. We demonstrate that a wide thermal tuning range, exceeding the C band, with a high side mode suppression ratio above 35 dB can be achieved. Design of external silicon cavities enables the realization of a broad range of on-chip functionalities as well as advanced hybrid transmitters. Parallel wavelength tunable cavities and compact variable optical attenuator-controlled arrayed waveguide gratings on silicon are integrated with a reflective semiconductor optical amplifiers, creating fast wavelength switching lasers. Furthermore, integrated transmitters that combine silicon modulators with tunable hybrid III–V/Si lasers are reported. The integrated transmitter for on–off keying signal generation exhibits more than 30 nm wavelength tunability and excellent bit-error-rate performance up to 40 Gb/s. A multichannel integrated transmitter is then reported with combined silicon-based arrayed waveguide gratings laser cavity and multiple ring modulators. Finally, an advanced wavelength-tunable hybrid III–V/Si transmitter with two microring modulators nested in a Mach–Zehnder interferometer is demonstrated for quadrature phase-shift keying generation where a BPSK signal is generated by each ring.

We propose a tunable dual-wavelength heterogeneous quantum dot laser diode. The tunable dual-wavelength laser consists of a quantum dot semiconductor optical amplifier as the optical gain medium and an external cavity fabricated from silicon photonics technology as the wavelength tunable filter. We successfully demonstrated dual-wavelength lasing oscillation by tuning the difference frequency from approximately 34 to 400 GHz.

Here, we report design and simulations of a vertical photodetector based on amorphous Ge2Sb2Te5 ( $a$ -GST) for silicon platform at telecommunication wavelength (1550 nm). In our investigations, it is found that $a$ -GST on silicon platform can be used as a waveguide photodetector with good responsivity and low dark current. Optimization of the structure is done to improve absorption, photocurrent, and corresponding electrical current at cathode. Our investigations reveal that ~150 nm is optimized thickness of $a$ -GST material for high responsivity (~48 A/W) when integrated on top of a single-mode silicon-on-insulator waveguide. This responsivity is comparable with existing avalanche photodiodes. With optimized dimensions, a good ratio of photocurrent to dark current is obtained. To the best of our knowledge, this is the first report on $a$ -GST-based photodetector.

The impacts of heavy-ion induced radial ionization profiles in integrated silicon photonic waveguides are investigated. Drude theory is applied to the case of a highly excited silicon waveguide to obtain relations for relevant optical properties to the heavy ion induced electron-hole pair density. 3-D finite-difference time-domain simulations are used to ascertain transmission characteristics through a variety of ionization profiles. Transient free-carrier absorption and phase shifts due to transient free-carrier dispersion are identified as potential single event effect degradation mechanisms for photonic integrated circuits operated in space.

A silicon heterostructure photovoltaic system fielded for 10 years has been investigated in detail. The system has shown degradation, but at a rate similar to an average Si system, and still within the module warranty level. The power decline is dominated by a nonlinear V oc loss rather than more typical changes in I sc or Fill Factor. Modules have been evaluated using multiple techniques including: dark and light I – V measurement, Suns- V oc, thermal imaging, and quantitative electroluminescence. All techniques indicate that recombination and series resistance in the cells have increased along with a decrease of factor 2 in minority carrier lifetime. Performance changes are fairly uniform across the module, indicating changes occur primarily within the cells.

Two-dimensional materials are compatible with silicon complementary metal-oxide semiconductor processes. As such, the integration of two-dimensional materials with silicon-based semiconductors could lead to an amalgamation of the beneficial properties of both silicon and the two-dimensional material thereby facilitating improved performance. Single-layer transition metal dichalcogenide materials like MoS2, MoTe2 and WS2 are characterized by direct band gaps and possess high emission efficiencies. These materials are, therefore, perfectly suited for ameliorating the optical emission inadequacies of silicon-based-materials. In this study, we integrate WS2 with a silicon-based silicon-nitride waveguide to modulate a 532-nm pump light source, and successfully modulate and amplify an optical signal at 640 nm. Compared to other modulators based on two-dimensional materials, e.g., graphene, the proposed WS2-based modulator theoretically incurs lower losses and exhibits higher contrast levels and signal-to-noise ...

The photovoltaics market has been growing rapidly in the past decade or so, driven by policy support, growing economies of scale, and technological improvements. Continued advances in photovoltaics...

Many biomedical sensing applications require high electrical sensitivity as well as a method to control and implement them into biological applications. This requires a material to have both conductive and biocompatible properties. Many conductive materials fail in these applications due to their lack of biocompatibility, and many biocompatible materials have very low conductivity. A method to control the conductivity of fibrous silicon through the laser processing of silicon covered with a thin film of gold (1μm) is detailed in this article. An Nd:YAG pulsed nanosecond laser was utilized to process the thin film at a line spacing of 0.025mm at different overlaps (number of laser beams scanning through the same path), for increasing the surface to volume ratio and biocompatibility of the single crystalline silicon. The biocompatibility assessment has shown positive results with traces of the elements necessary for the formation of hydroxyapatite. Samples processed at a lower power showed higher concentrations of these trace elements, suggesting an increase in biocompatibility. Overall, this research offers preliminary findings as to the direction and future work that can be done with porous silicon to offer a cost effective and efficient method of enhancing the conductivity and biocompatibility for biomedical sensing and conductive tissue engineering applications. Keywords: Laser materials processing, Biosensor, Nanofibrous structures, Nanofabrication, Silicon-based sensor

This paper presents a method for fabrication of flexible silicon sensor chips using temporary bonding, backside thinning, debonding, and flexible packaging. Flexibility of silicon chips requires ultrathin thickness, which imposes a challenge to debonding of thinned silicon chips from carrier wafers because of the fragility of silicon. To address this problem, temporary bonding using polypropylene carbonate (PPC), a heat-depolymerizable polymer material, as bonding adhesive is developed. PPC allows damage-free detachment of ultrathin silicon chips from carrier wafers by heating after backside thinning. The method is demonstrated and applied to the fabrication of silicon stress sensor chips with thickness down to $30~\mu \text{m}$ . The measurement results show that the ultrathin silicon chips have good flexibility and function well. The processes are optimized, and the detailed parameters are reported. The preliminary results demonstrate the feasibility of the method, and show its potential application in the fabrication of flexible ultrathin silicon sensors.

One of the current challenges in photonics is developing high-speed, power-efficient, chip-integrated optical communications devices to address the interconnects bottleneck in high-speed computing systems. Silicon photonics has emerged as a leading architecture, in part because of the promise that many components, such as waveguides, couplers, interferometers and modulators, could be directly integrated on silicon-based processors. However, light sources and photodetectors present ongoing challenges. Common approaches for light sources include one or few off-chip or wafer-bonded lasers based on III-V materials, but recent system architecture studies show advantages for the use of many directly modulated light sources positioned at the transmitter location. The most advanced photodetectors in the silicon photonic process are based on germanium, but this requires additional germanium growth, which increases the system cost. The emerging two-dimensional transition-metal dichalcogenides (TMDs) offer a path for optical interconnect components that can be integrated with silicon photonics and complementary metal-oxide-semiconductors (CMOS) processing by back-end-of-the-line steps. Here, we demonstrate a silicon waveguide-integrated light source and photodetector based on a p-n junction of bilayer MoTe2, a TMD semiconductor with an infrared bandgap. This state-of-the-art fabrication technology provides new opportunities for integrated optoelectronic systems.

Several trace gases such as H2O, CO, CO2, NO, N2O, NO2 and CH4 strongly absorb in the mid-IR spectral region due to their fundamental rotational and vibrational transitions. In this work, we propos...

Silicon carbide (SiC) power devices have been investigated extensively in the past two decades, and there are many devices commercially available now. Owing to the intrinsic material advantages of SiC over silicon (Si), SiC power devices can operate at higher voltage, higher switching frequency, and higher temperature. This paper reviews the technology progress of SiC power devices and their emerging applications. The design challenges and future trends are summarized at the end of the paper.

As an alternative approach to conventional lithography based fabrication, simple methodology of ultrafast laser writing followed by chemical processing for fabrication of silicon microstructures is studied and presented. Laser fluence and number of pulses dependent laser-matter interaction study reveals several concurrent extreme nonlinearities that influence the structural morphology in both longitudinal and transverse directions. High intensity femtosecond pulse propagation produces inevitable structural features, such as quasi aperiodic surface textures, V-shaped craters, re-casted melt and debris. To minimize such undesired effects, isotropic and anisotropic chemical etching processes have been systematically optimized. Such hybrid protocols resulted into definite microstructures, with surface quality comparable to those obtained from other lithographic fabrication methods. The proposed methodology is expected to provide control over desired feature sizes, for large-scale and cost-effective fabrication of microstructures for many optoelectronics applications.

In this paper we review the silicon microfabrication process that has been developed for various life science applications over the last several years. Silicon microfabrication is a key enabling technology in the developing personalized point of care or point of need systems. Silicon microfabrication allows for accurate control of fine features and it can combine active and passive components within a single chip. It is also very reliable, repeatable and it benefits from cost reduction due to mass production capabilities Depending on the application, we have fabricated devices with either a single silicon etch or a two-step approach. Single step etches are typically 250–280μm deep. Two-step etching, the shallow features are 50μm while deeper are 250μm. We have developed an optimized deep silicon etch process that gives very straight profiles with minimum loss of critical dimension (CD) for different features. The minimum CD is 3μm while the largest features are 500μm wide The etching was done an SPTS Rapier DRIE system. We describe the working principles of the various components in the system including PCR and micropillar filters. The filter has been used for high performance liquid chromatography (HPLC). It exhibits very low broadening of the components travelling through it and separation of a mixture of coumarin dyes is efficiently performed in a very short time. A micro PCR chamber with thermal isolation to the surrounding silicon is characterized and DNA amplification is achieved.

The hallmark of silicon photonics is in its low loss at the telecommunications wavelength, economic advantages and compatibility with CMOS design and fabrication processes. These advantages are however impeded by its relatively low Kerr coefficient that constrains the power and size scaling of nonlinear all-optical silicon photonic devices. Graphene, with its unprecedented high Kerr coefficient and uniquely thin-film structure, makes a good nonlinear material to be easily integrated onto all-optical silicon photonic waveguide devices. We study the design of all-optical graphene-on-silicon (GOS) waveguide modulators, and find the optimized performance of MW cm−2 in optical pump intensities and sub-mm device lengths. The improvements brought by the integration of graphene onto silicon photonic waveguides could bring us a step closer to realising compact all-optical control on a single chip.

The accurate detection of ultraviolet light (UV) has been playing important roles in a variety of fields such as industrial and agricultural production, environmental monitoring and protection, defense and aerospace industries. Semiconductor materials have been widely used in fabricating various photodectors. As a representative of the first generation semiconductor materials, silicon has been applied to fabricate UV photodetector for a long time. For example, the first solid UV detectors were based on UV-enhanced silicon photodiode. Nevertheless, silicon-based photodiodes usually exhibit responses to visible light, which will cause serious disturbances for the detection of UV. Furthermore, crystal silicon is an indirect bandgap semiconductor, which decides that its conversion efficiency and therefore responsivity during the optoelectronic process would be low. All these shortcomings make the effort on developing novel UV photodetectors being both important and necessary. In the past years, great progresses have been achieved in preparing high-quality compound semiconductors with direct and wide bandgaps, and this provides a good opportunity for developing high-performance UV photodectors. As a III-V compound semiconductor with a direct and wide bandgap (~3.4 eV), gallium nitride (GaN) possesses the properties of high electronic mobility and heat conductivity, good chemical and thermal stability, and excellent anti-irradiation capability, and therefore is thought to be one of the most suitable materials for preparing UV detectors. Currently, high-quality GaN thin films are usually prepared by heteroepitaxy technology utilizing sapphire wafers as substrates. However, sapphire is an insulator, which can be used only as a mechanical support instead of a functional substrate and might bring additional technical difficulty in device integration. Such a problem might be solved by using silicon substrate, provided that the large lattice and thermal mismatch between silicon and GaN can be conquered, or it will cause serious problems relating to the device performance and operation stability. A proved method is through introducing nanostructured silicon substrates to construct GaN/Si heterojunction, by which the mismatches could be greatly diminished through a three-dimensional stress release mode at the GaN and silicon interface. Silicon nanoporous pillar array (Si-NPA) is a silicon hierarchical structure characterized by a regular array of well separated, micron-sized and highly nanoporous silicon pillars, and it has been proved an ideal template for preparing silicon-based heterstructures with high-quality interfaces. Here we will report that utilizing Si-NPA as substrates, GaN/Si-NPA nanoheterojunctions were prepared by growing GaN nanocrystallites using a chemical vapor deposition method. Through changing the deposition time, the surface morphology, chemical constitution, and electrical and photoluminescent properties of GaN/Si-NPA can be tuned effectively, and this provided a solid foundation for optimizing the device performance of the subsequently developed UV photodetectors. Through preparing ITO top transparent electrodes and silver back electrodes on these nanoheterojunctions, prototype UV photodectors with a device structure of ITO/GaN/Si-NPA/ sc -Si/Ag were prepared and the photodetection properties were studied. It was shown that high-quality UV detection can be realized without applying any bias, with the response and recovery time being ~0.12 s and ~0.24 s, respectively. For the monochromatic UV light with a wavelength of 340 nm, a responsivity of ~0.15 mA/W was achieved. These results might have provided a novel route for developing Si-based GaN UV photodetectors.

We develop a process of fabricating silicon waveguides and devices using a bulk silicon substrate. The fabrication process mainly consists of one silicon dry etching and one silicon wet etching. The use of silicon wet etching makes the process simple and inexpensive. Because of the anisotropic nature of silicon wet etching, the bulk-silicon-based (BSB) waveguide made by the process consists of an inverted-trapezoidal core on a rectangular pedestal and a trapezoidal base beneath the pedestal. In addition, geometrically smooth BSB waveguide bends can be achieved when the radii of curvature of the bends are sufficiently large. The propagation loss of the BSB waveguide depends on wet etching conditions and it is 4.0 or 0.79 dB/cm for transverse-magnetic polarization. It is confirmed that the minimum radius of curvature of the BSB waveguide bend is 500 μm. The BSB waveguides and bends are expected to be used to implement low-cost sensors with simple geometry.

Optical interconnection using photons as information carriers is one of the trends in silicon integrated circuits. However, the realization of silicon-based optical interconnection must be dependent of efficient silicon-based light sources that are compatible with current IC manufacturing processes. In this paper, our research results of silicon-based light sources in recent years are summarized with special emphasis on the latest progress in silicon-based luminescent materials and devices, including silicon quantum dots, silicon crystal defects, silicon-based nitrogen oxide films and silicon-based oxide semiconductor films.

The aim of this work is to study the possibility of reducing the labor consumption and cost of high-power silicon transistor manufacturing without compromise in transistor low thermal resistance. To this end we experimentally explored replacing Au-Si solder with lead-silver solder or other solders for silicon chip soldering in transistor housings. This will reduce gold consumption and increase the efficiency of high-power transistor silicon chip installation due to the use of batch soldering technology. We also studied the effect of different silicon wafer back side treatment and thinning methods on the thermal resistance of the transistors. To improve the soldering quality we applied preliminary Ti–Ni metallization of the reverse side of the silicon wafer. We experimentally assessed the effect of outer housing layer materials and back side chip metallization. For lead-silver soldering of silicon chips, the best housing is that with a nickel outer layer rather than with a gold-plated one, because the resultant thermal resistance is lower and the absence of gold makes the technology cheaper. We obtained a 0.6 K/W thermal resistance for a 24 mm2 chip area.

Impurity-mediated near-infrared (NIR) photoresponse in silicon is of great interest for photovoltaics and photodetectors. In this paper, we have fabricated a series of n+/p photodetectors with hyperdoped silicon prepared by ion-implantation and femtosecond pulsed laser. These devices showed a remarkable enhancement on absorption and photoresponse at NIR wavelengths. The device fabricated with implantation dose of 1014 ions/cm2 has exhibited the best performance. The proposed method offers an approach to fabricate low-cost broadband silicon-based photodetectors.

This paper presents temperature sensitivity analysis of a silicon-polymer hybrid photonic micro-ring resonator. Photonic micro-ring resonators have hailed for their potential used in the next generation optical communications. However, like any other optical devices, temperature fluctuations alter the functionality of the micro-ring resonator. Hence, this paper provides a proposal for solution to minimize the temperature sensitive effect on the resonance characteristics. The temperature sensitivity effect of the pure silicon micro-ring resonaltor has been investigated. It is shown that the pure silicon micro-ring resonator is very sensitive to temperature. We added a negative thermo-optic polymer material with the positive thermo-optic silicon material to investigate the efeect of temperature sensitivity. Simulation tool Lumerical solution has been used to simulate the ring resonator. A polymer material of LFR is used to analyze the temperature effects. The hybrid composition of silicon-polymer were as 30%-70%, 40%-60%, 50%-50% and 60%-40% to investigate the temperature effect. The simulation was carried out using a ring size of 5 um, 10 um, 15 um and 20 um. The results show that the temperature insensitive ring resonator is possible with a 42% LFR polymer mixwd with 58% silicon.

A 3D integrated hybrid silicon laser was realized for high-thermal performance by integrating silicon photonic (SiPh) chips and indium phosphide (InP) chips. The optical gain is provided by the InP chip with a total internal reflection mirror for surface emission. The surface grating couplers on the SiPh chip couples light into a silicon waveguide. The InP chips were flip-chip bonded P-side down to metal pads on the silicon chips. Two lasers are reported. For laser A, the InP chip was bonded on the top cladding oxide of the silicon waveguide. For laser B, the InP chip was bonded to the silicon substrate in an etched recess. Both lasers demonstrate milliwatt-level light coupled into the silicon waveguide. Laser B demonstrated three times better thermal performance with a measured thermal impedance of 6.2 °C/W.

Amorphous silicon nitride has become the state-of-the-art antireflection coating for silicon solar cells. Optimization of silicon nitride films requires consideration of both the film's optical and electrical properties. It is commonly assumed that silicon-rich silicon nitride films (films with high refractive index) provide better surface passivation, compared to that obtained by films with lower indices. However, silicon-rich films are usually very absorptive in the short (and even medium) wavelength range. Development of low absorption silicon nitride films, that provide good surface passivation, is therefore highly valuable. In this study we compare nine different industrial silicon nitride films, all with similarly low refractive index of 2.09 ± 0.01 measured at 633 nm. We demonstrate that these films exhibit very different electrical, chemical, and optical properties despite their similar refractive index values and correlate these differences with the specific deposition conditions. As a result of this investigation, we have developed industrial thermally stable low-absorbing silicon nitride films that provide excellent surface passivation, with surface saturation current density of 7 fA/cm2 on both n- and p-type wafers. We demonstrate that the developed low absorption films provide surface passivation with equal quality to that obtained by industrial silicon-rich silicon nitride films.

A room temperature silicon co-integrated light source module was realized by using a selective area metal bonding method, which is able to evanescently couple the light from InGaAsP multi-quantum well laser diodes into silicon waveguide. The module consists of a four-wavelength InGaAsP-Si hybrid laser array and a $4\times1$ silicon multimode interference (MMI) optical coupler on silicon-on-insulator platform. Its output wavelength can be accurately tuned around 1550 nm through controlling the width of the slotted silicon waveguides. The MMI specifically engineered for $C$ -band can be patterned and formed just by photolithography and inductively coupled plasma. The ease in fabrication makes this type of devices a promising candidate for wavelength division multiplex in future optical communication system.

On-chip nanophotonics offer high throughput, yet energy-efficient communication, traits that can prove critical to the continuance of multicore chip scalability. In this paper we investigate and propose silicon nanophotonic components that are embedded entirely in the silica (SiO2) substrate, i.e., reside subsurface, as opposed to die on-surface silicon nanophotonics of prior-art. Among several offered advantages, such Siliconin-Silica (SiS) nanophotonic structures empower the implementation of non-obstructive interconnect geometries that deliver an improved power-performance balance, as demonstrated experimentally. First, using exhaustive simulations based on commercial-grade optical software-based tools, we show that such SiS structures are feasible, and derive their geometry characteristics and design parameters. As a second step, utilizing SiS optical channels and filters, we then design two distinct SiS-based nanoPhotonic Network-on-Chip (PNoC) mesh-diagonal links topologies as a means of demonstrating our proof of concept. In further pushing the performance envelope, we next develop (1) an associated contention-aware adaptive routing function, and (2) a parallelized photonic channel allocation scheme, with both coupled to SiS-based PNoCs as elements, to respectively replace under-performing routing and flow-control photonic protocols currently utilized. An extensive experimental evaluation, including utilizing traffic benchmarks gathered from full-system chip multiprocessor simulations, shows that our methodology boosts network throughput by up to 59:7%, reduces communication latency by up to 78:7%, while improving the throughput-to-power ratio by up to 31:6% when compared to the state-of-the-art.

Silicon photonics has been developed successfully with a top-down fabrication technique to enable large-scale photonic integrated circuits with high reproducibility, but is limited intrinsically by the material capability for active or nonlinear applications. On the other hand, free-standing nanowires synthesized via a bottom-up growth present great material diversity and structural uniformity, but precisely assembling free-standing nanowires for on-demand photonic functionality remains a great challenge. Here we report hybrid integration of free-standing nanowires into silicon photonics with high flexibility by coupling free-standing nanowires onto target silicon waveguides that are simultaneously used for precise positioning. Coupling efficiency between a free-standing nanowire and a silicon waveguide is up to ~97% in the telecommunication band. A hybrid nonlinear-free-standing nanowires–silicon waveguides Mach–Zehnder interferometer and a racetrack resonator for significantly enhanced optical modulation are experimentally demonstrated, as well as hybrid active-free-standing nanowires–silicon waveguides circuits for light generation. These results suggest an alternative approach to flexible multifunctional on-chip nanophotonic devices., Precisely assembling free-standing nanowires for on-demand photonic functionality remains a challenge. Here, Chen et al. integrate free-standing nanowires into silicon waveguides and show all-optical modulation and light generation on silicon photonic chips.

This paper presents a comprehensive overview of the development and utilization of a micromachined silicon-on-insulator (SOI) fabrication process that has enabled the development of terahertz (THz) frequency superconducting-insulator-superconducting (SIS) and hot-electron bolometer (HEB) mixers, broadband directional couplers, on-wafer probes, as well as several multipliers. Through the detailed presentation of these circuits, it is demonstrated that ultrathin silicon is able to provide the required characteristics to enable the heterogeneous integration of multiple device technologies that is likely to be required for future THz system-on-chip (T-SoC) development.

We report on the development of a multipixel hot electron bolometer (HEB) receiver fabricated using silicon membrane technology. The receiver comprises a $2\,\times \,2$ array of four HEB mixers, fabricated on a single chip. The HEB mixer chip is based on a superconducting NbN thin-film deposited on top of the silicon-on-insulator (SOI) substrate. The thicknesses of the device layer and handling layer of the SOI substrate are 20 and 300 μm, respectively. The thickness of the device layer is chosen such that it corresponds to a quarter-wave in silicon at 1.35 THz. The HEB mixer is integrated with a bow-tie antenna structure, in turn designed for coupling to a circular waveguide, fed by a monolithic drilled smooth-walled horn array.

In order to decrease the dispersion of the silicon vertical slot waveguide, we propose a multilayered hybrid silicon vertical waveguide structure. This multilayered waveguide is formed by three low-refractive-index regions interleaved with two narrow silicon rails. Simulation shows that the optical field in the central low-index region is enhanced. After optimization, the dispersion of the waveguide can be limited within ±300 ps/nm/km from 1450 to 1950 nm. This multilayered waveguide has potential in on-chip nonlinear optical applications, such as in all-optical signal processing.

In this article we address the nanoscale engineering of the effective index of silicon on insulator waveguides by using plasmonic metasurface resonances to realize a graded index lens. We report the design, implementation, and experimental demonstration of this plasmonic metasurface-based graded index lens integrated on a silicon waveguide for operation in the near-infrared domain. The 2D-graded index lens consists of an array of gold cut wires fabricated on the top of a silicon waveguide. These gold cut wires modify locally the effective index of the silicon waveguide and allow the realization of this gradient lens. The reported solution represents a promising alternative to the bulky or multilayered metamaterials approach in the near IR domain. This enabling technology may have found its place in silicon photonic applications by exploiting the plasmonic resonances to control the light at nanoscale.

We propose a platform based on III−V compound semiconductor nanopillars monolithically integrated with silicon photonics. Nanopillars were grown in a process free of metal catalysts onto silicon at low temperature, and a bottom-up process was applied to define the photonic integrated circuit. Stimulated and spontaneous emissions from the nanopillars are direct coupled to silicon waveguides.

High-speed, high-efficiency photodetectors play an important role in optical communication links that are increasingly being used in data centres to handle higher volumes of data traffic and higher bandwidths, as big data and cloud computing continue to grow exponentially. Monolithic integration of optical components with signal-processing electronics on a single silicon chip is of paramount importance in the drive to reduce cost and improve performance. We report the first demonstration of micro- and nanoscale holes enabling light trapping in a silicon photodiode, which exhibits an ultrafast impulse response (full-width at half-maximum) of 30 ps and a high efficiency of more than 50%, for use in data-centre optical communications. The photodiode uses micro- and nanostructured holes to enhance, by an order of magnitude, the absorption efficiency of a thin intrinsic layer of less than 2 µm thickness and is designed for a data rate of 20 gigabits per second or higher at a wavelength of 850 nm. Further optimization can improve the efficiency to more than 70%. Light-trapping nanoscale holes are exploited to improve the speed and efficiency of silicon photodiodes with intrinsic layers less than 2 μm thick.

In this paper, the design, fabrication, and high-frequency characterization of three types of nontraditional through-silicon via (TSV) technologies are discussed. First, the integration of TSVs within a silicon microfluidic heat sink is presented; TSVs are fabricated within a pin-fin heat sink, and the frequency response of TSVs within a deionized-water-filled silicon pin-fin heat sink is experimentally analyzed. Second, to electrically shield the signal transmission of such TSVs, coaxially shielded TSVs consisting of multiple ground TSVs surrounding a single signal TSV are demonstrated. It is experimentally shown that as the number of ground TSVs increases, shielding is improved. Finally, a partial air-isolation technique is proposed to reduce TSV loss and capacitance at high frequencies.