Silicon Avalanche Photodetectors Research Articles

Modeling the Impact of Fabrication Variabilities on the Performance of Silicon Avalanche Photodetectors

Modeling the Impact of Fabrication Variabilities on the Performance of Silicon Avalanche Photodetectors

Visible-Light Integrated PIN Avalanche Photodetectors With High Responsivity and Bandwidth

Integrated photodetectors are key building blocks of scalable photonics platforms. Many recent improvements have been made for integrated avalanche photodetectors (APDs) operating at infrared telecommunications wavelengths, but their visible-spectrum counterparts remain relatively unexplored. Here, we demonstrate PIN-doped silicon APDs for visible light detection, monolithically integrated with a silicon nitride photonics circuit via end-fire coupling. An in-depth study of multiple PIN doping profiles reveals different optimal designs based on the desired operating regimes. At −49 dBm input power, they show 0.25 A/W (0.8 A/W) responsivity at reverse bias as low as 0.5 V (5.5 V), with corresponding dark current of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$&lt; $</tex-math></inline-formula> 3 pA (50 pA). We also report fast RF response with an optimal 3 dB bandwidth of 11 GHz and gain-bandwidth product of 142 GHz, with all devices yielding open eye diagrams at 25 Gbps or above. Coupled with CMOS-compatible fabrication, our APDs will enable scalable photonics applications in sensing, communications, and quantum technologies at visible wavelengths.

Towards Integrated Single Photon Avalanche Detectors for Visible Light (Invited)

Integrated avalanche photodetectors (APDs) are essential and ubiquitous devices in quantum photonics applications. While free-space APDs are a mature technology, the development of integrated APDs for visible light is still in its infancy. In this invited talk, we review our work on integrated photodetectors – the Germanium photodetector for O band, and the first integrated silicon (Si) APD for visible light. A unique feature of the integrated Si APD system for visible light is the end-fire coupling between the silicon nitride (SiN) waveguide and the Si APD in the same layer. This allows for broadband and high-efficiency coupling of light from the SiN waveguide to the Si APD for light detection, without the drawbacks of conventional interlayer coupling. Our work on integrated Si APDs based on Geiger-mode and our progress towards achieving single photon detection for visible light is discussed in the talk.

A Near-Infrared CMOS Silicon Avalanche Photodetector with Ultra-Low Temperature Coefficient of Breakdown Voltage.

Silicon avalanche photodetector (APD) plays a very important role in near-infrared light detection due to its linear controllable gain and attractive manufacturing cost. In this paper, a silicon APD with punch-through structure is designed and fabricated by standard 0.5 μm complementary metal oxide semiconductor (CMOS) technology. The proposed structure eliminates the requirements for wafer-thinning and the double-side metallization process by most commercial Si APD products. The fabricated device shows very low level dark current of several tens Picoamperes and ultra-high multiplication gain of ~4600 at near-infrared wavelength. The ultra-low extracted temperature coefficient of the breakdown voltage is 0.077 V/K. The high performance provides a promising solution for near-infrared weak light detection.

AlGaInP optical source integrated with fiber links and silicon avalanche photo detectors in fiber optic systems

This study has clarified aluminium gallium indium phosphide (AlGaInP) optical source integrated with fiber links and silicon avalanche photodetectors in fiber optic systems. The output spectral power, rise time, signal frequency and resonance frequency for AlGaInP laser diode. The laser diode rise time, output spectral power and resonance/signal frequencies versus injection current and ambient temperatures are sketched. The silica doped germanium fiber link pulse broadening and the signal fiber bandwidth are investigated against temperature variations. The signal per noise ratio is related to Q value and bit error rate (BER) at the receiving point (Si avalanche photodetector (APD)) are sketched with temperature.

Multispectral fluorescence lifetime imaging device with a silicon avalanche photodetector.

We report the design, development, and characterization of a novel multi-spectral fluorescence lifetime measurement device incorporating solid-state detectors and automated gain control. For every excitation pulse (∼1 µJ, 600 ps), this device records complete fluorescence decay from multiple spectral channels simultaneously within microseconds, using a dedicated UV enhanced avalanche photodetector and analog to digital convert (2.5 GS/s) in each channel. Fast (<2 ms) channel-wise dynamic range adjustment maximizes the signal-to-noise ratio. Fluorophores with known lifetime ranging from 0.5-6.0 ns were used to demonstrate the device accuracy. Current results show the clear benefits of this device compared to existing devices employing microchannel-plate photomultiplier tubes. This is demonstrated by 5-fold reduction of lifetime measurement variability in identical conditions, independent gain adjustment in each spectral band, and 4-times faster imaging speed. The use of solid-state detectors will also facilitate future improved performance and miniaturization of the instrument.

Температурная зависимость чувствительности кремниевых фотоумножителей в режиме пофотонной регистрации ультрафиолетового излучения

In the context of the development of a new detecting camera for the Cherenkov gamma-ray telescope TAIGA-IACT, the temperature dependences of the dark count rate and the efficiency of ultraviolet photon detection of two silicon avalanche photodetectors: OnSemi / SensL MicroFJ-60035 and Hamamatsu VUV4 S13371-6050CQ-02 at a wavelength of 277 nm were experimentally investigated. It is shown that the main characteristics of these detectors correspond to those declared by the manufacturers. Front-end readout electronics was developed and tested. Conclusions are drawn about the applicability of such detectors in the detecting cameras of Cherenkov gamma-ray telescopes.

Reliability of Silicon Avalanche Photodetector in Geiger Mode

Due to high gain, Avalanche Photodetector (APD) in Geiger mode can detect single-photon signal. In this paper, a method for assessing the reliability of silicon APDs in Geiger mode is proposed, including the rapid estimation of APD fault activation energy (Ea), the analysis of APD failure mechanisms and assessment of lifetime. The test time and temperature interval were optimized using Arrhenius formula according to the stress limit and failure activation energy. Compared to 980,000h, the expected lifetime of our samples, the test time is greatly shortened, proving the high efficiency of our method. The main cause of fail may be the increase of surface leakage current, which will be verified in subsequent tests. Failure rate increases with time in wear out phase, and strongly depends on the structure of the device. Therefore, it is of great significance to improve the device design.

DEVICE FOR BINARY DATA TRANSMITTING AND RECEIVING OVER A FIBEROPTIC COMMUNICATION CHANNEL

When transferring data over optical fiber communication channels, it is required to provide data security and the authenticity of their source. To limit the access to the data for a third party, there can be applied quantum-cryptographical systems which are supposed to transfer every data bit by means of low power optical signals containing radiation photons the number of which could be in the range from 10 to 1, however, are far from being perfect and suffer from shortcomings, the main of which being a large number of errors due to the depolarization effect of optical radiation. The aim of this work was, therefore, to create device for sending and receiving confidential data which could provide complete security of transferred data, inherent to quantum-cryptographical communication systems at the same time could have a low number of such errors.A device for quantum-cryptographic communication system with a photon counter applied as a receiving module has been proposed. The possibility to use silicon avalanche photodetectors operating in the photon counting mode for confidential information transmission systems and defining authenticity of the source of transmitted information has been shown.I develop modern optical fiber communication system incorporating avalanche photodetector photon counter as a receiving module, that allow to detect unauthorized access to information and violation of its integrity and speed up the exchange of information in comparison with well-known quantum-cryptographical communication systems.

Performance Optimization and Improvement of Silicon Avalanche Photodetectors in Standard CMOS Technology

This paper discusses design optimization for silicon avalanche photodetectors (APDs) fabricated in standard complementary metal-oxide-semiconductor (CMOS) technology in order to achieve the highest possible performance. Such factors as PN junctions, guard ring structures, active areas, and back-end structures are considered for the optimization. CMOS-APDs reflecting varying aspects of these factors are fabricated and their performances are characterized. In addition, their characteristics are analyzed with technology computer-aided-design simulations and equivalent circuit models. From these investigations, dominant factors that influence the CMOS-APD performance are identified. Furthermore, three different techniques enabling further performance improvements of CMOS-APDs are investigated, which are spatial-modulation, carrier-acceleration, and multijunction techniques. The state-of-the-art CMOS-APDs’ structures and performances are presented and compared, and the best optimized CMOS-APD is proposed. These results should be extremely useful for realizing optimal silicon APDs in standard CMOS technology for various applications.

First CMOS Silicon Avalanche Photodetectors With Over 10-GHz Bandwidth

This letter reports on the first silicon avalanche photodetectors (APDs) with over 10-GHz bandwidth. Three types of APDs based on P+/N-well junction are realized in standard complementary metal–oxide–semiconductor (CMOS) technology. For bandwidth improvement, the CMOS-compatible APDs (CMOS-APDs) are designed to be smaller active area, and a spatially-modulated avalanche photodetector (SM-APD) is also proposed in order to further reduce the bandwidth limiting factor of the CMOS-APDs. Current–voltage characteristics, responsivities, and photodetection frequency responses of the three APDs are measured and compared, and the photodetection bandwidth characteristics are analyzed with an equivalent circuit model to identify the origin of the bandwidth improvement. The proposed small-area CMOS-APD provides 10-GHz bandwidth with high responsivity, and the SM-APD achieves 12-GHz bandwidth, which is the largest bandwidth ever reported for silicon photodetectors in standard CMOS technology.

Effects of Parasitic Resistance on the Performance of Silicon Avalanche Photodetectors in Standard CMOS Technology

We investigate the effects of parasitic resistance on the performance of silicon avalanche photodetectors (APDs) fabricated in the standard complementary metal–oxide–semiconductor (CMOS) technology. Two types of CMOS-APDs based on the P+/N-well junction having two different parasitic resistances are realized, and their current–voltage characteristics, responsivities, avalanche gains, photodetection frequency responses, and electrical reflection coefficients are measured and compared. In addition, the effect of parasitic resistance on the photodetection bandwidth is analyzed with an equivalent circuit model. It is clearly demonstrated that the parasitic resistance has great effects on the gain and photodetection bandwidth of CMOS-APDs.

Bandwidth Improvement of CMOS-APD With Carrier-Acceleration Technique

We present a silicon avalanche photodetector (APD) based on multiple P + /N-well junctions fabricated in standard complementary metal-oxide-semiconductor (CMOS) technology. In order to overcome the photodetection-bandwidth limitation of the CMOS-APD based on P + /N-well junction, carrier-acceleration technique is proposed. With this technique, the photogenerated carriers in the charge-neutral N-well region are accelerated by the extrinsic electric field. To induce the extrinsic electric field inside N-well, the CMOS-APD is designed with multiple junctions to reduce the distance between two different N-well biasing contacts. Its performance is simulated and measured with different bias voltages applied to N-well, and it is demonstrated that the CMOS-APD with the carrier-acceleration technique provides higher photodetection bandwidth.

An integrated platform for simultaneous multi-well field potential recording and Fura-2-based calcium transient ratiometry in human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes

IntroductionHuman induced pluripotent stem cell-derived cardiomyocytes are available from various sources and they are being evaluated for safety testing. Several platforms are available offering different assay principles and read-out parameters: patch-clamp and field potential recording, imaging or photometry, impedance measurement, and recording of contractile force. Routine use will establish which assay principle and which parameters best serve the intended purpose. MethodsWe introduce a combination of field potential recording and calcium ratiometry from spontaneously beating cardiomyocytes as a novel assay providing a complementary read-out parameter set. Field potential recording is performed using a commercial multi-well multi-electrode array platform. Calcium ratiometry is performed using a fiber optic illumination and silicon avalanche photodetectors. Data condensation and statistical analysis are designed to enable statistical inference of differences and equivalence with regard to a solvent control. ResultsSimultaneous recording of field potentials and calcium transients from spontaneously beating monolayers was done in a nine-well format. Calcium channel blockers (e.g. nifedipine) and a blocker of calcium store release (ryanodine) can be recognized and discriminated based on the calcium transient signal. An agonist of L-type calcium channels, FPL 64176, increased and prolonged the calcium transient, whereas BAY K 8644, another L-type calcium channel agonist, had no effect. Both FPL 64176 and various calcium channel antagonists have chronotropic effects, which can be discriminated from typical “chronotropic” compounds, like (±)isoprenaline (positive) and arecaidine propargyl ester (negative), based on their effects on the calcium transient. DiscussionDespite technical limitations in temporal resolution and exact matching of composite calcium transient with the field potential of a subset of cells, the combined recording platform enables a refined interpretation of the field potential recording and a more reliable identification of drug effects on calcium handling.

Optical-Power Dependence of Gain, Noise, and Bandwidth Characteristics for 850-nm CMOS Silicon Avalanche Photodetectors

We investigate the effects of incident optical powers on the performance of 850-nm silicon avalanche photodetectors (APDs) realized with P + /N-well junctions in standard CMOS technology. The current-voltage characteristics, responsivities, avalanche gains, noise power spectral densities, excess noise factors, electrical reflection coefficients, and photodetection frequency responses of the fabricated CMOS-APD are measured for different incident optical powers. In addition, the photodetection frequency responses at different incident optical powers are modeled with equivalent circuits and the influence of the optical power on photodetection bandwidth is analyzed. From these, we show that, near the avalanche breakdown voltage, the CMOS-APD avalanche gain and excess noise factor increase and photodetection bandwidth decreases with decreasing incident optical power. These results should be very useful for realizing high-performance CMOS integrated optical receivers for various optical-interconnect applications.

Operation of Multi-Pixel Photon Counters Down to Liquid Helium Temperatures

We are investigating the possibility of using Silicon Avalanche Photo Detectors (APD), both in proportional and in Geiger mode, to readout inorganic scintillators operated at cryogenic temperatures. Such detectors, that need to operate close to liquid helium (LHe) temperatures and in a magnetic field of a few Tesla, have been proposed by our group as a way to build an active polarized target to be used for neutrino physics, for the search of axions and CP violation, as suggested by some theoretical papers. In the present work we investigate in some details the performance of Hamamatsu Multi-Pixel Photon Counters (MPPCs) down to LHe temperature to verify the temperature range of usability of these devices.

A High-Speed and Low-Breakdown-Voltage Silicon Avalanche Photodetector

A silicon avalanche photodetector with a low breakdown voltage of -6.78 V is demonstrated by narrowing down the intrinsic layer width of interdigitated p-i-n junctions to ~ 150 nm. It reaches the physical limit of avalanche breakdown in which the performance degradation caused by the Zener tunneling process is negligible. Dark current at -4 V is measured, and a responsivity (gain) exceeding 1.424 A/W (110) at -6.75 V is obtained with an 850-nm laser illumination. The intrinsic bandwidth is determined to be 10 GHz, suggesting our device is applicable for a 10-Gb/s high-speed optical receiver application and beyond.

SNR characteristics of 850-nm OEIC receiver with a silicon avalanche photodetector

We investigate signal-to-noise ratio (SNR) characteristics of an 850-nm optoelectronic integrated circuit (OEIC) receiver fabricated with standard 0.25-µm SiGe bipolar complementary metal-oxide-semiconductor (BiCMOS) technology. The OEIC receiver is composed of a Si avalanche photodetector (APD) and BiCMOS analog circuits including a transimpedance amplifier with DC-balanced buffer, a tunable equalizer, a limiting amplifier, and an output buffer with 50-Ω loads. We measure APD SNR characteristics dependence on the reverse bias voltage as well as BiCMOS circuit noise characteristics. From these, we determine the SNR characteristics of the entire OEIC receiver, and finally, the results are verified with bit-error rate measurement.

Narrow Band Source of Transform-Limited Photon Pairs via Four-Wave Mixing in a Cold Atomic Ensemble

We observe narrow band pairs of time-correlated photons of wavelengths 776 and 795 nm from nondegenerate four-wave mixing in a laser-cooled atomic ensemble of ^{87}Rb using a cascade decay scheme. Coupling the photon pairs into single mode fibers, we observe an instantaneous rate of 7700 pairs per second with silicon avalanche photodetectors, and an optical bandwidth below 30 MHz. Detection events exhibit a strong correlation in time [g((2))(τ = 0) ≈ 5800] and a high coupling efficiency indicated by a pair-to-single ratio of 23%. The violation of the Cauchy-Schwarz inequality by a factor of 8.4 × 10(6) indicates a strong nonclassical correlation between the generated fields, while a Hanbury Brown-Twiss experiment in the individual photons reveals their thermal nature. The comparison between the measured frequency bandwidth and 1/e decay time of g((2)) indicates a transform-limited spectrum of the photon pairs. The narrow bandwidth and brightness of our source makes it ideal for interacting with atomic ensembles in quantum communication protocols.

Area-Dependent Photodetection Frequency Response Characterization of Silicon Avalanche Photodetectors Fabricated With Standard CMOS Technology

We investigate the area-dependent characteristics of photodetection frequency responses of 850-nm silicon avalanche photodetectors (APDs) fabricated with standard complementary metal-oxide-semiconductor (CMOS) technology. CMOS-compatible APDs (CMOS-APDs) based on a p+/n-well junction with four different device areas are used for the investigation, and we identify factors that influence photodetection frequency responses with the goal of achieving optimal photodetection bandwidth performance. Their current-voltage characteristics, electrical reflection coefficients, and photodetection frequency responses are measured, and the characteristics of the CMOS-APD photodetection frequency responses are analyzed using equivalent circuit models. From this, it is clarified how the four different factors of photogenerated-carrier transit time, device RC time constant, inductive-peaking effect, and parasitics contribute to the photodetection frequency responses and how their contribution changes with device areas. Among the four types of CMOS-APDs investigated in this study, the 10 × 10 μm2 CMOS-APD has the largest 3-dB photodetection bandwidth of 7.6 GHz.