Low Noise and High Photodetection Probability SPAD in 180 nm Standard CMOS Technology

A square shaped, low noise and high photo-response single photon avalanche diode suitable for circuit integration, implemented in a standard CMOS 180 nm high voltage technology, is presented. In this work, a p+ to shallow n-well junction was engineered with a very smooth electric field profile guard ring to attain a photo detection probability peak higher than 50% with a median dark count rate lower than 2 Hz/μm2 when operated at an excess bias of 4 V. The reported timing jitter full width at half maximum is below 300 ps for 640 nm laser pulses

Compact CMOS active quenching/recharge circuit for SPAD arrays

Avalanche diodes operating in Geiger mode are able to detect single photon events. They can be employed to photon counting and time-of-flight estimation. In order to ensure proper operation of these devices, the avalanche current must be rapidly quenched, and, later on, the initial equilibrium must be restored. In this paper, we present an active quenching/recharge circuit specially designed to be integrated in the form of an array of single-photon avalanche diode (SPAD) detectors. Active quenching and recharge provide benefits like an accurately controllable pulse width and afterpulsing reduction. In addition, this circuit yields one of the lowest reported area occupations and power consumptions. The quenching mechanism employed is based on a positive feedback loop that accelerates quenching right after sensing the avalanche current. We have employed a current starved inverter for the regulation of the hold-off time, which is more compact than other reported controllable delay implementations. This circuit has been fabricated in a standard 0.18 μm complementary metal-oxide-semiconductor (CMOS) technology. The SPAD has a quasi-circular shape of 12 μm diameter active area. The fill factor is about 11%. The measured time resolution of the detector is 187 ps. The photon-detection efficiency (PDE) at 540 nm wavelength is about 5% at an excess voltage of 900 mV. The break-down voltage is 10.3 V. A dark count rate of 19 kHz is measured at room temperature. Worst case post-layout simulations show a 117 ps quenching and 280 ps restoring times. The dead time can be accurately tuned from 5 to 500 ns. The pulse-width jitter is below 1.8 ns when dead time is set to 40 ns.Ministerio de Economía y Competitividad TEC2012-38921-C02, IPT-2011-1625-430000, IPC-20111009 CDTIJunta de Andalucía TIC 2338-2013Office of Naval Research (USA) N00014141035

Evolution and Recent Developments of the Gaseous Photon Detectors Technologies

The evolution and the present status of the gaseous photon detectors technologies are reviewed. The most recent developments in several branches of the field are described, in particular the installation and commissioning of the first large area MPGD-based detectors of single photons on COMPASS RICH-1. Investigation of novel detector architectures, different materials and various applications are reported, and the quest for visible light gaseous photon detectors is discussed. The progress on the use of gaseous photon detector related techniques in the field of cryogenic applications and gaseous or liquid scintillation imaging are presented.Comment: NDIP 2017 Proceedings, review, submitted to Nuc. Inst. Methods

Silicon Photomultiplier for the Plug & Imaging PET system: Physics, Technological Challenges and Application to Modern Nuclear Medicine

We propose the design of a Silicon Photomultiplier at the 180 nm GLOBALFOUNDRIES BCDLITE CMOS technology node. We perform a characterization of the device, in comparison with other results obtained a CMOS technology node and we investigate the limits and strengths of this approach. Finally we show possible future applications of the SiPM in Nuclear Medicine, in particular to digital positron emission tomography systems

SPAD Figures of Merit for Photon-Counting, Photon-Timing, and Imaging Applications: A Review

Single-photon avalanche diodes (SPADs) emerged as the most suitable photodetectors for both single-photon counting and photon-timing applications. Different complementary metal-oxide-semiconductor (CMOS) devices have been reported in the literature, with quite different performance and some excelling in just few of them, but often at different operating conditions. In order to provide proper criteria for performance assessment, we present some figures of merit (FoMs) able to summarize the typical SPAD performance (i.e., photon detection efficiency, dark counting rate, afterpulsing probability, hold-off time, and timing jitter) and to identify a proper metric for SPAD comparisons, when used either as single-pixel detectors or in imaging arrays. The ultimate goal is not to define a ranking list of best-in-class detectors, but to quantitatively help the end-user to state the overall performance of different SPADs in either photon-counting, timing, or imaging applications. We review many CMOS SPADs from different research groups and companies, we compute the proposed FoMs for all them and, eventually, we provide an insight on present CMOS SPAD technologies and future trends

Single-Photon Avalanche Diodes in a 0.16 μm BCD Technology With Sharp Timing Response and Red-Enhanced Sensitivity

CMOS single-photon avalanche diodes (SPADs) have recently become an emerging imaging technology for applications requiring high sensitivity and high frame-rate in the visible and near-infrared range. However, a higher photon detection efficiency (PDE), particularly in the 700-950 nm range, is highly desirable for many growing markets, such as eye-safe three-dimensional imaging (LIDAR). In this paper, we report the design and characterization of SPADs fabricated in a 0.16 mu m BCD (Bipolar-CMOS-DMOS) technology. The overall detection performance is among the best reported in the literature: 1) PDE of 60% at 500 nm wavelength and still 12% at 800 nm; 2) very low dark count rate of < 0.2 cps/mu m(2) (in counts per second per unit area); 3) < 1% afterpulsing probability with 50 ns dead-time; and 4) temporal response with 30 ps full width at half-maximum and less than 50 ps diffusion tail time constant

A 64x64 SPAD array for portable colorimetric sensing, fluorescence and X-ray imaging

We present the design and application of a 64x64 pixel SPAD array to portable colorimetric sensing, and fluorescence and x-ray imaging. The device was fabricated on an unmodified 180 nm CMOS process and is based on a square p+/n active junction SPAD geometry suitable for detecting green fluorescence emission. The stand-alone SPAD shows a photodetection probability greater than 60% at 5 V excess bias, with a dark count rate of less than 4 cps/µm2 and sub-ns timing jitter performance. It has a global shutter with an in-pixel 8-bit counter; four 5-bit decoders and two 64-to-1 multiplexer blocks allow the data to be read-out. The array of sensors was able to detect fluorescence from a fluorescein isothiocyanate (FITC) solution down to a concentration of 900 pM with a SNR of 9.8 dB. A colorimetric assay was performed on top of the sensor array with a limit of quantification of 3.1 µM. X-rays images, using energies ranging from 10 kVp to 100 kVp, of a lead grating mask were acquired without using a scintillation crystal

Enhancing the fill-factor of CMOS SPAD arrays using microlens integration

Arrays of single-photon avalanche diode (SPAD) detectors were fabricated, using a 0.35 μm CMOS technology process, for use in applications such as time-of-flight 3D ranging and microscopy. Each 150 x 150 μm pixel comprises a 30 μm active area diameter SPAD and its associated circuitry for counting, timing and quenching, resulting in a fill-factor of 3.14%. This paper reports how a higher effective fill-factor was achieved as a result of integrating microlens arrays on top of the 32 x 32 SPAD arrays. Diffractive and refractive microlens arrays were designed to concentrate the incoming light onto the active area of each pixel. A telecentric imaging system was used to measure the improvement factor (IF) resulting from microlens integration, whilst varying the f-number of incident light from f/2 to f/22 in one-stop increments across a spectral range of 500-900 nm. These measurements have demonstrated an increasing IF with fnumber, and a maximum of ~16 at the peak wavelength, showing a good agreement with theoretical values. An IF of 16 represents the highest value reported in the literature for microlenses integrated onto a SPAD detector array. The results from statistical analysis indicated the variation of detector efficiency was between 3-10% across the whole f-number range, demonstrating excellent uniformity across the detector plane with and without microlenses

Recent advances and future perspectives of single-photon avalanche diodes for quantum photonics applications

Photonic quantum technologies promise a revolution of the world of information processing, from simulation and computing to communication and sensing, thanks to the many advantages of exploiting single photons as quantum information carriers. In this scenario, single-photon detectors play a key role. On the one hand, superconducting nanowire single-photon detectors (SNSPDs) are able to provide remarkable performance on a broad spectral range, but their applicability is often limited by the need of cryogenic operating temperatures. On the other hand, single-photon avalanche diodes (SPADs) overcome the intrinsic limitations of SNSPDs by providing a valid alternative at room temperature or slightly below. In this paper, we review the fundamental principles of the SPAD operation and we provide a thorough discussion of the recent progress made in this field, comparing the performance of these devices with the requirements of the quantum photonics applications. In the end, we conclude with our vision of the future by summarizing prospects and unbeaten paths that can open new perspectives in the field of photonic quantum information processing