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Special Issue "Photon-Counting Image Sensors"

A special issue of Sensors (ISSN 1424-8220). This special issue belongs to the section "Physical Sensors".

Deadline for manuscript submissions: closed (12 February 2016)

Special Issue Editors

Guest Editor
Prof. Dr. Eric R. Fossum

Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire, USA, and co-founder, International Image Sensor Society
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Co-Guest Editor
Prof. Dr. Nobukazu Teranishi

University of Hyogo, Hyogo, Japan and Shizuoka University, Shizuoka, Japan, and co-founder, International Image Sensor Society
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Co-Guest Editor
Prof. Dr. Albert Theuwissen

Harvest Imaging, Bree, Belgium and Delft University of Technology, Delft, Netherlands, and co-founder, International Image Sensor Society
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Co-Guest Editor
Dr. David Stoppa

Smart Optical Sensors and Interfaces Unit, Bruno Kessler Foundation, Trento, Italy
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Co-Guest Editor
Prof. Dr. Edoardo Charbon

Chair of VLSI Design, Department of Microelectronics, Delft University of Technology, Delft, Netherlands
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Special Issue Information

Dear Colleagues,

The field of photon-counting image sensors is advancing rapidly with the development of various solid-state image sensor technologies including single photon avalanche detectors (SPADs) and deep-sub-electron read noise CMOS image sensor pixels. This foundational platform technology will enable opportunities for new imaging modalities and instrumentation for science and industry, as well as new consumer applications. Papers discussing various photon-counting image sensor technologies and selected new applications are presented in this all-invited Special Issue.

Prof. Dr. Eric R. Fossum
Prof. Dr. Edoardo Charbon
Dr. David Stoppa
Prof. Dr. Nobukazu Teranishi
Prof. Dr. Albert Theuwissen
Guest Editors

Submission

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are refereed through a peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Sensors is an international peer-reviewed Open Access monthly journal published by MDPI.

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Keywords

  • Photon-counting
  • Single photon detection
  • Image sensor
  • SPAD
  • avalanche photodetector
  • Deep sub-electron read noise
  • Quanta image sensor

Published Papers (22 papers)

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Research

Jump to: Review

Open AccessArticle Images from Bits: Non-Iterative Image Reconstruction for Quanta Image Sensors
Sensors 2016, 16(11), 1961; doi:10.3390/s16111961
Received: 8 September 2016 / Revised: 3 November 2016 / Accepted: 17 November 2016 / Published: 22 November 2016
PDF Full-text (2815 KB) | HTML Full-text | XML Full-text
Abstract
A quanta image sensor (QIS) is a class of single-photon imaging devices that measure light intensity using oversampled binary observations. Because of the stochastic nature of the photon arrivals, data acquired by QIS is a massive stream of random binary bits. The goal
[...] Read more.
A quanta image sensor (QIS) is a class of single-photon imaging devices that measure light intensity using oversampled binary observations. Because of the stochastic nature of the photon arrivals, data acquired by QIS is a massive stream of random binary bits. The goal of image reconstruction is to recover the underlying image from these bits. In this paper, we present a non-iterative image reconstruction algorithm for QIS. Unlike existing reconstruction methods that formulate the problem from an optimization perspective, the new algorithm directly recovers the images through a pair of nonlinear transformations and an off-the-shelf image denoising algorithm. By skipping the usual optimization procedure, we achieve orders of magnitude improvement in speed and even better image reconstruction quality. We validate the new algorithm on synthetic datasets, as well as real videos collected by one-bit single-photon avalanche diode (SPAD) cameras. Full article
(This article belongs to the Special Issue Photon-Counting Image Sensors)
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Open AccessArticle Noise Reduction Effect of Multiple-Sampling-Based Signal-Readout Circuits for Ultra-Low Noise CMOS Image Sensors
Sensors 2016, 16(11), 1867; doi:10.3390/s16111867
Received: 12 August 2016 / Revised: 28 October 2016 / Accepted: 1 November 2016 / Published: 6 November 2016
PDF Full-text (7142 KB) | HTML Full-text | XML Full-text
Abstract
This paper discusses the noise reduction effect of multiple-sampling-based signal readout circuits for implementing ultra-low-noise image sensors. The correlated multiple sampling (CMS) technique has recently become an important technology for high-gain column readout circuits in low-noise CMOS image sensors (CISs). This paper reveals
[...] Read more.
This paper discusses the noise reduction effect of multiple-sampling-based signal readout circuits for implementing ultra-low-noise image sensors. The correlated multiple sampling (CMS) technique has recently become an important technology for high-gain column readout circuits in low-noise CMOS image sensors (CISs). This paper reveals how the column CMS circuits, together with a pixel having a high-conversion-gain charge detector and low-noise transistor, realizes deep sub-electron read noise levels based on the analysis of noise components in the signal readout chain from a pixel to the column analog-to-digital converter (ADC). The noise measurement results of experimental CISs are compared with the noise analysis and the effect of noise reduction to the sampling number is discussed at the deep sub-electron level. Images taken with three CMS gains of two, 16, and 128 show distinct advantage of image contrast for the gain of 128 (noise(median): 0.29 erms) when compared with the CMS gain of two (2.4 erms), or 16 (1.1 erms). Full article
(This article belongs to the Special Issue Photon-Counting Image Sensors)
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Open AccessArticle A 72 × 60 Angle-Sensitive SPAD Imaging Array for Lens-less FLIM
Sensors 2016, 16(9), 1422; doi:10.3390/s16091422
Received: 31 May 2016 / Revised: 16 August 2016 / Accepted: 26 August 2016 / Published: 2 September 2016
PDF Full-text (16738 KB) | HTML Full-text | XML Full-text
Abstract
We present a 72 × 60, angle-sensitive single photon avalanche diode (A-SPAD) array for lens-less 3D fluorescence lifetime imaging. An A-SPAD pixel consists of (1) a SPAD to provide precise photon arrival time where a time-resolved operation is utilized to avoid stimulus-induced saturation,
[...] Read more.
We present a 72 × 60, angle-sensitive single photon avalanche diode (A-SPAD) array for lens-less 3D fluorescence lifetime imaging. An A-SPAD pixel consists of (1) a SPAD to provide precise photon arrival time where a time-resolved operation is utilized to avoid stimulus-induced saturation, and (2) integrated diffraction gratings on top of the SPAD to extract incident angles of the incoming light. The combination enables mapping of fluorescent sources with different lifetimes in 3D space down to micrometer scale. Futhermore, the chip presented herein integrates pixel-level counters to reduce output data-rate and to enable a precise timing control. The array is implemented in standard 180 nm complementary metal-oxide-semiconductor (CMOS) technology and characterized without any post-processing. Full article
(This article belongs to the Special Issue Photon-Counting Image Sensors)
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Open AccessArticle Development of Gated Pinned Avalanche Photodiode Pixels for High-Speed Low-Light Imaging
Sensors 2016, 16(8), 1294; doi:10.3390/s16081294
Received: 29 February 2016 / Revised: 8 August 2016 / Accepted: 10 August 2016 / Published: 15 August 2016
PDF Full-text (4160 KB) | HTML Full-text | XML Full-text
Abstract
This work explores the benefits of linear-mode avalanche photodiodes (APDs) in high-speed CMOS imaging as compared to different approaches present in literature. Analysis of APDs biased below their breakdown voltage employed in single-photon counting mode is also discussed, showing a potentially interesting alternative
[...] Read more.
This work explores the benefits of linear-mode avalanche photodiodes (APDs) in high-speed CMOS imaging as compared to different approaches present in literature. Analysis of APDs biased below their breakdown voltage employed in single-photon counting mode is also discussed, showing a potentially interesting alternative to existing Geiger-mode APDs. An overview of the recently presented gated pinned avalanche photodiode pixel concept is provided, as well as the first experimental results on a 8 × 16 pixel test array. Full feasibility of the proposed pixel concept is not demonstrated; however, informative data is obtained from the sensor operating under −32 V substrate bias and clearly exhibiting wavelength-dependent gain in frontside illumination. The readout of the chip designed in standard 130 nm CMOS technology shows no dependence on the high-voltage bias. Readout noise level of 15 e - rms, full well capacity of 8000 e - , and the conversion gain of 75 µV / e - are extracted from the photon-transfer measurements. The gain characteristics of the avalanche junction are characterized on separate test diodes showing a multiplication factor of 1.6 for red light in frontside illumination. Full article
(This article belongs to the Special Issue Photon-Counting Image Sensors)
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Open AccessArticle Single Photon Counting Performance and Noise Analysis of CMOS SPAD-Based Image Sensors
Sensors 2016, 16(7), 1122; doi:10.3390/s16071122
Received: 21 January 2016 / Revised: 4 July 2016 / Accepted: 12 July 2016 / Published: 20 July 2016
Cited by 3 | PDF Full-text (3125 KB) | HTML Full-text | XML Full-text
Abstract
SPAD-based solid state CMOS image sensors utilising analogue integrators have attained deep sub-electron read noise (DSERN) permitting single photon counting (SPC) imaging. A new method is proposed to determine the read noise in DSERN image sensors by evaluating the peak separation and width
[...] Read more.
SPAD-based solid state CMOS image sensors utilising analogue integrators have attained deep sub-electron read noise (DSERN) permitting single photon counting (SPC) imaging. A new method is proposed to determine the read noise in DSERN image sensors by evaluating the peak separation and width (PSW) of single photon peaks in a photon counting histogram (PCH). The technique is used to identify and analyse cumulative noise in analogue integrating SPC SPAD-based pixels. The DSERN of our SPAD image sensor is exploited to confirm recent multi-photon threshold quanta image sensor (QIS) theory. Finally, various single and multiple photon spatio-temporal oversampling techniques are reviewed. Full article
(This article belongs to the Special Issue Photon-Counting Image Sensors)
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Open AccessArticle Photon-Counting Arrays for Time-Resolved Imaging
Sensors 2016, 16(7), 1005; doi:10.3390/s16071005
Received: 18 February 2016 / Revised: 24 May 2016 / Accepted: 16 June 2016 / Published: 29 June 2016
Cited by 3 | PDF Full-text (9302 KB) | HTML Full-text | XML Full-text
Abstract
The paper presents a camera comprising 512 × 128 pixels capable of single-photon detection and gating with a maximum frame rate of 156 kfps. The photon capture is performed through a gated single-photon avalanche diode that generates a digital pulse upon photon detection
[...] Read more.
The paper presents a camera comprising 512 × 128 pixels capable of single-photon detection and gating with a maximum frame rate of 156 kfps. The photon capture is performed through a gated single-photon avalanche diode that generates a digital pulse upon photon detection and through a digital one-bit counter. Gray levels are obtained through multiple counting and accumulation, while time-resolved imaging is achieved through a 4-ns gating window controlled with subnanosecond accuracy by a field-programmable gate array. The sensor, which is equipped with microlenses to enhance its effective fill factor, was electro-optically characterized in terms of sensitivity and uniformity. Several examples of capture of fast events are shown to demonstrate the suitability of the approach. Full article
(This article belongs to the Special Issue Photon-Counting Image Sensors)
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Open AccessArticle Quantum Random Number Generation Using a Quanta Image Sensor
Sensors 2016, 16(7), 1002; doi:10.3390/s16071002
Received: 6 April 2016 / Revised: 13 June 2016 / Accepted: 23 June 2016 / Published: 29 June 2016
Cited by 1 | PDF Full-text (1260 KB) | HTML Full-text | XML Full-text
Abstract
A new quantum random number generation method is proposed. The method is based on the randomness of the photon emission process and the single photon counting capability of the Quanta Image Sensor (QIS). It has the potential to generate high-quality random numbers with
[...] Read more.
A new quantum random number generation method is proposed. The method is based on the randomness of the photon emission process and the single photon counting capability of the Quanta Image Sensor (QIS). It has the potential to generate high-quality random numbers with remarkable data output rate. In this paper, the principle of photon statistics and theory of entropy are discussed. Sample data were collected with QIS jot device, and its randomness quality was analyzed. The randomness assessment method and results are discussed. Full article
(This article belongs to the Special Issue Photon-Counting Image Sensors)
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Open AccessArticle X-ray Photon Counting and Two-Color X-ray Imaging Using Indirect Detection
Sensors 2016, 16(6), 764; doi:10.3390/s16060764
Received: 27 January 2016 / Revised: 26 April 2016 / Accepted: 23 May 2016 / Published: 26 May 2016
Cited by 2 | PDF Full-text (7276 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, we report on the design and performance of a 1 cm2, 90 × 92-pixel image sensor. It is made X-ray sensitive by the use of a scintillator. Its pixels have a charge packet counting circuit topology with two
[...] Read more.
In this paper, we report on the design and performance of a 1 cm2, 90 × 92-pixel image sensor. It is made X-ray sensitive by the use of a scintillator. Its pixels have a charge packet counting circuit topology with two channels, each realizing a different charge packet size threshold and analog domain event counting. Here, the sensor’s performance was measured in setups representative of a medical X-ray environment. Further, two-energy-level photon counting performance is demonstrated, and its capabilities and limitations are documented. We then provide an outlook on future improvements. Full article
(This article belongs to the Special Issue Photon-Counting Image Sensors)
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Open AccessArticle Particle and Photon Detection: Counting and Energy Measurement
Sensors 2016, 16(5), 688; doi:10.3390/s16050688
Received: 22 March 2016 / Revised: 19 April 2016 / Accepted: 4 May 2016 / Published: 12 May 2016
Cited by 1 | PDF Full-text (7706 KB) | HTML Full-text | XML Full-text
Abstract
Fundamental limits for photon counting and photon energy measurement are reviewed for CCD and CMOS imagers. The challenges to extend photon counting into the visible/nIR wavelengths and achieve energy measurement in the UV with specific read noise requirements are discussed. Pixel flicker and
[...] Read more.
Fundamental limits for photon counting and photon energy measurement are reviewed for CCD and CMOS imagers. The challenges to extend photon counting into the visible/nIR wavelengths and achieve energy measurement in the UV with specific read noise requirements are discussed. Pixel flicker and random telegraph noise sources are highlighted along with various methods used in reducing their contribution on the sensor’s read noise floor. Practical requirements for quantum efficiency, charge collection efficiency, and charge transfer efficiency that interfere with photon counting performance are discussed. Lastly we will review current efforts in reducing flicker noise head-on, in hopes to drive read noise substantially below 1 carrier rms. Full article
(This article belongs to the Special Issue Photon-Counting Image Sensors)
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Open AccessArticle Analysis of Subthreshold Current Reset Noise in Image Sensors
Sensors 2016, 16(5), 663; doi:10.3390/s16050663
Received: 26 January 2016 / Revised: 13 April 2016 / Accepted: 4 May 2016 / Published: 10 May 2016
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Abstract
To discuss the reset noise generated by slow subthreshold currents in image sensors, intuitive and simple analytical forms are derived, in spite of the subthreshold current nonlinearity. These solutions characterize the time evolution of the reset noise during the reset operation. With soft
[...] Read more.
To discuss the reset noise generated by slow subthreshold currents in image sensors, intuitive and simple analytical forms are derived, in spite of the subthreshold current nonlinearity. These solutions characterize the time evolution of the reset noise during the reset operation. With soft reset, the reset noise tends to m k T / 2 C P D when t , in full agreement with previously published results. In this equation, C P D is the photodiode (PD) capacitance and m is a constant. The noise has an asymptotic time dependence of t 1 , even though the asymptotic time dependence of the average (deterministic) PD voltage is as slow as log t . The flush reset method is effective because the hard reset part eliminates image lag, and the soft reset part reduces the noise to soft reset level. The feedback reset with reverse taper control method shows both a fast convergence and a good reset noise reduction. When the feedback amplifier gain, A, is larger, even small value of capacitance, C P , between the input and output of the feedback amplifier will drastically decrease the reset noise. If the feedback is sufficiently fast, the reset noise limit when t , becomes m k T ( C P D + C P 1 ) 2 2 q 2 A ( C P D + ( 1 + A ) C P ) in terms of the number of electron in the PD. According to this simple model, if CPD = 10 fF, CP/CPD = 0.01, and A = 2700 are assumed, deep sub-electron rms reset noise is possible. Full article
(This article belongs to the Special Issue Photon-Counting Image Sensors)
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Open AccessArticle The DEPFET Sensor-Amplifier Structure: A Method to Beat 1/f Noise and Reach Sub-Electron Noise in Pixel Detectors
Sensors 2016, 16(5), 608; doi:10.3390/s16050608
Received: 7 February 2016 / Revised: 12 April 2016 / Accepted: 18 April 2016 / Published: 28 April 2016
Cited by 1 | PDF Full-text (2860 KB) | HTML Full-text | XML Full-text
Abstract
Depleted field effect transistors (DEPFET) are used to achieve very low noise signal charge readout with sub-electron measurement precision. This is accomplished by repeatedly reading an identical charge, thereby suppressing not only the white serial noise but also the usually constant 1/f noise.
[...] Read more.
Depleted field effect transistors (DEPFET) are used to achieve very low noise signal charge readout with sub-electron measurement precision. This is accomplished by repeatedly reading an identical charge, thereby suppressing not only the white serial noise but also the usually constant 1/f noise. The repetitive non-destructive readout (RNDR) DEPFET is an ideal central element for an active pixel sensor (APS) pixel. The theory has been derived thoroughly and results have been verified on RNDR-DEPFET prototypes. A charge measurement precision of 0.18 electrons has been achieved. The device is well-suited for spectroscopic X-ray imaging and for optical photon counting in pixel sensors, even at high photon numbers in the same cell. Full article
(This article belongs to the Special Issue Photon-Counting Image Sensors)
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Open AccessArticle Noise Reduction Techniques and Scaling Effects towards Photon Counting CMOS Image Sensors
Sensors 2016, 16(4), 514; doi:10.3390/s16040514
Received: 25 January 2016 / Revised: 24 March 2016 / Accepted: 6 April 2016 / Published: 9 April 2016
Cited by 3 | PDF Full-text (791 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents an overview of the read noise in CMOS image sensors (CISs) based on four-transistors (4T) pixels, column-level amplification and correlated multiple sampling. Starting from the input-referred noise analytical formula, process level optimizations, device choices and circuit techniques at the pixel
[...] Read more.
This paper presents an overview of the read noise in CMOS image sensors (CISs) based on four-transistors (4T) pixels, column-level amplification and correlated multiple sampling. Starting from the input-referred noise analytical formula, process level optimizations, device choices and circuit techniques at the pixel and column level of the readout chain are derived and discussed. The noise reduction techniques that can be implemented at the column and pixel level are verified by transient noise simulations, measurement and results from recently-published low noise CIS. We show how recently-reported process refinement, leading to the reduction of the sense node capacitance, can be combined with an optimal in-pixel source follower design to reach a sub-0.3 \(e^{-}_{rms}\) read noise at room temperature. This paper also discusses the impact of technology scaling on the CIS read noise. It shows how designers can take advantage of scaling and how the Metal-Oxide-Semiconductor (MOS) transistor gate leakage tunneling current appears as a challenging limitation. For this purpose, both simulation results of the gate leakage current and 1/f noise data reported from different foundries and technology nodes are used. Full article
(This article belongs to the Special Issue Photon-Counting Image Sensors)
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Open AccessArticle Reduction of CMOS Image Sensor Read Noise to Enable Photon Counting
Sensors 2016, 16(4), 517; doi:10.3390/s16040517
Received: 1 February 2016 / Revised: 29 March 2016 / Accepted: 31 March 2016 / Published: 9 April 2016
Cited by 2 | PDF Full-text (8499 KB) | HTML Full-text | XML Full-text
Abstract
Recent activity in photon counting CMOS image sensors (CIS) has been directed to reduction of read noise. Many approaches and methods have been reported. This work is focused on providing sub 1 e read noise by design and operation of the binary
[...] Read more.
Recent activity in photon counting CMOS image sensors (CIS) has been directed to reduction of read noise. Many approaches and methods have been reported. This work is focused on providing sub 1 e read noise by design and operation of the binary and small signal readout of photon counting CIS. Compensation of transfer gate feed-through was used to provide substantially reduced CDS time and source follower (SF) bandwidth. SF read noise was reduced by a factor of 3 with this method. This method can be applied broadly to CIS devices to reduce the read noise for small signals to enable use as a photon counting sensor. Full article
(This article belongs to the Special Issue Photon-Counting Image Sensors)
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Open AccessArticle Vision without the Image
Sensors 2016, 16(4), 484; doi:10.3390/s16040484
Received: 2 February 2016 / Revised: 26 March 2016 / Accepted: 4 April 2016 / Published: 6 April 2016
PDF Full-text (1588 KB) | HTML Full-text | XML Full-text
Abstract
Novel image sensors transduce the stream of photons directly into asynchronous electrical pulses, rather than forming an image. Classical approaches to vision start from a good quality image and therefore it is tempting to consider image reconstruction as a first step to image
[...] Read more.
Novel image sensors transduce the stream of photons directly into asynchronous electrical pulses, rather than forming an image. Classical approaches to vision start from a good quality image and therefore it is tempting to consider image reconstruction as a first step to image analysis. We propose that, instead, one should focus on the task at hand (e.g., detection, tracking or control) and design algorithms that compute the relevant variables (class, position, velocity) directly from the stream of photons. We discuss three examples of such computer vision algorithms and test them on simulated data from photon-counting sensors. Such algorithms work just-in-time, i.e., they complete classification, search and tracking with high accuracy as soon as the information is sufficient, which is typically before there are enough photons to form a high-quality image. We argue that this is particularly useful when the photons are few or expensive, e.g., in astronomy, biological imaging, surveillance and night vision. Full article
(This article belongs to the Special Issue Photon-Counting Image Sensors)
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Open AccessArticle Single-Photon Avalanche Diode with Enhanced NIR-Sensitivity for Automotive LIDAR Systems
Sensors 2016, 16(4), 459; doi:10.3390/s16040459
Received: 20 January 2016 / Revised: 25 March 2016 / Accepted: 25 March 2016 / Published: 30 March 2016
Cited by 2 | PDF Full-text (4630 KB) | HTML Full-text | XML Full-text
Abstract
A single-photon avalanche diode (SPAD) with enhanced near-infrared (NIR) sensitivity has been developed, based on 0.18 μm CMOS technology, for use in future automotive light detection and ranging (LIDAR) systems. The newly proposed SPAD operating in Geiger mode achieves a high NIR photon
[...] Read more.
A single-photon avalanche diode (SPAD) with enhanced near-infrared (NIR) sensitivity has been developed, based on 0.18 μm CMOS technology, for use in future automotive light detection and ranging (LIDAR) systems. The newly proposed SPAD operating in Geiger mode achieves a high NIR photon detection efficiency (PDE) without compromising the fill factor (FF) and a low breakdown voltage of approximately 20.5 V. These properties are obtained by employing two custom layers that are designed to provide a full-depletion layer with a high electric field profile. Experimental evaluation of the proposed SPAD reveals an FF of 33.1% and a PDE of 19.4% at 870 nm, which is the laser wavelength of our LIDAR system. The dark count rate (DCR) measurements shows that DCR levels of the proposed SPAD have a small effect on the ranging performance, even if the worst DCR (12.7 kcps) SPAD among the test samples is used. Furthermore, with an eye toward vehicle installations, the DCR is measured over a wide temperature range of 25–132 °C. The ranging experiment demonstrates that target distances are successfully measured in the distance range of 50–180 cm. Full article
(This article belongs to the Special Issue Photon-Counting Image Sensors)
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Review

Jump to: Research

Open AccessReview Towards a Graphene-Based Low Intensity Photon Counting Photodetector
Sensors 2016, 16(9), 1351; doi:10.3390/s16091351
Received: 19 February 2016 / Revised: 15 July 2016 / Accepted: 15 August 2016 / Published: 23 August 2016
PDF Full-text (6232 KB) | HTML Full-text | XML Full-text
Abstract
Graphene is a highly promising material in the development of new photodetector technologies, in particular due its tunable optoelectronic properties, high mobilities and fast relaxation times coupled to its atomic thinness and other unique electrical, thermal and mechanical properties. Optoelectronic applications and graphene-based
[...] Read more.
Graphene is a highly promising material in the development of new photodetector technologies, in particular due its tunable optoelectronic properties, high mobilities and fast relaxation times coupled to its atomic thinness and other unique electrical, thermal and mechanical properties. Optoelectronic applications and graphene-based photodetector technology are still in their infancy, but with a range of device integration and manufacturing approaches emerging this field is progressing quickly. In this review we explore the potential of graphene in the context of existing single photon counting technologies by comparing their performance to simulations of graphene-based single photon counting and low photon intensity photodetection technologies operating in the visible, terahertz and X-ray energy regimes. We highlight the theoretical predictions and current graphene manufacturing processes for these detectors. We show initial experimental implementations and discuss the key challenges and next steps in the development of these technologies. Full article
(This article belongs to the Special Issue Photon-Counting Image Sensors)
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Open AccessReview The Quanta Image Sensor: Every Photon Counts
Sensors 2016, 16(8), 1260; doi:10.3390/s16081260
Received: 24 April 2016 / Revised: 1 August 2016 / Accepted: 2 August 2016 / Published: 10 August 2016
Cited by 1 | PDF Full-text (7848 KB) | HTML Full-text | XML Full-text
Abstract
The Quanta Image Sensor (QIS) was conceived when contemplating shrinking pixel sizes and storage capacities, and the steady increase in digital processing power. In the single-bit QIS, the output of each field is a binary bit plane, where each bit represents the presence
[...] Read more.
The Quanta Image Sensor (QIS) was conceived when contemplating shrinking pixel sizes and storage capacities, and the steady increase in digital processing power. In the single-bit QIS, the output of each field is a binary bit plane, where each bit represents the presence or absence of at least one photoelectron in a photodetector. A series of bit planes is generated through high-speed readout, and a kernel or “cubicle” of bits (x, y, t) is used to create a single output image pixel. The size of the cubicle can be adjusted post-acquisition to optimize image quality. The specialized sub-diffraction-limit photodetectors in the QIS are referred to as “jots” and a QIS may have a gigajot or more, read out at 1000 fps, for a data rate exceeding 1 Tb/s. Basically, we are trying to count photons as they arrive at the sensor. This paper reviews the QIS concept and its imaging characteristics. Recent progress towards realizing the QIS for commercial and scientific purposes is discussed. This includes implementation of a pump-gate jot device in a 65 nm CIS BSI process yielding read noise as low as 0.22 e− r.m.s. and conversion gain as high as 420 µV/e−, power efficient readout electronics, currently as low as 0.4 pJ/b in the same process, creating high dynamic range images from jot data, and understanding the imaging characteristics of single-bit and multi-bit QIS devices. The QIS represents a possible major paradigm shift in image capture. Full article
(This article belongs to the Special Issue Photon-Counting Image Sensors)
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Open AccessReview Three-Dimensional Photon Counting Imaging with Axially Distributed Sensing
Sensors 2016, 16(8), 1184; doi:10.3390/s16081184
Received: 25 March 2016 / Revised: 7 July 2016 / Accepted: 25 July 2016 / Published: 28 July 2016
PDF Full-text (3275 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, we review three-dimensional (3D) photon counting imaging with axially distributed sensing. Under severely photon-starved conditions, we have proposed various imaging and algorithmic approaches to reconstruct a scene in 3D, which are not possible by using conventional imaging system due to
[...] Read more.
In this paper, we review three-dimensional (3D) photon counting imaging with axially distributed sensing. Under severely photon-starved conditions, we have proposed various imaging and algorithmic approaches to reconstruct a scene in 3D, which are not possible by using conventional imaging system due to lack of sufficient number of photons. In this paper, we present an overview of optical sensing and imaging system along with dedicated algorithms for reconstructing 3D scenes by photon counting axially distributed sensing, which may be implemented by moving a single image sensor along its optical axis. To visualize the 3D image, statistical estimation methods and computational reconstruction of axially distributed sensing is applied. Full article
(This article belongs to the Special Issue Photon-Counting Image Sensors)
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Open AccessReview Single Photon Counting UV Solar-Blind Detectors Using Silicon and III-Nitride Materials
Sensors 2016, 16(6), 927; doi:10.3390/s16060927
Received: 31 March 2016 / Revised: 5 June 2016 / Accepted: 7 June 2016 / Published: 21 June 2016
Cited by 2 | PDF Full-text (7061 KB) | HTML Full-text | XML Full-text
Abstract
Ultraviolet (UV) studies in astronomy, cosmology, planetary studies, biological and medical applications often require precision detection of faint objects and in many cases require photon-counting detection. We present an overview of two approaches for achieving photon counting in the UV. The first approach
[...] Read more.
Ultraviolet (UV) studies in astronomy, cosmology, planetary studies, biological and medical applications often require precision detection of faint objects and in many cases require photon-counting detection. We present an overview of two approaches for achieving photon counting in the UV. The first approach involves UV enhancement of photon-counting silicon detectors, including electron multiplying charge-coupled devices and avalanche photodiodes. The approach used here employs molecular beam epitaxy for delta doping and superlattice doping for surface passivation and high UV quantum efficiency. Additional UV enhancements include antireflection (AR) and solar-blind UV bandpass coatings prepared by atomic layer deposition. Quantum efficiency (QE) measurements show QE > 50% in the 100–300 nm range for detectors with simple AR coatings, and QE ≅ 80% at ~206 nm has been shown when more complex AR coatings are used. The second approach is based on avalanche photodiodes in III-nitride materials with high QE and intrinsic solar blindness. Full article
(This article belongs to the Special Issue Photon-Counting Image Sensors)
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Open AccessReview Compact SPAD-Based Pixel Architectures for Time-Resolved Image Sensors
Sensors 2016, 16(5), 745; doi:10.3390/s16050745
Received: 7 March 2016 / Revised: 25 April 2016 / Accepted: 16 May 2016 / Published: 23 May 2016
Cited by 2 | PDF Full-text (3992 KB) | HTML Full-text | XML Full-text
Abstract
This paper reviews the state of the art of single-photon avalanche diode (SPAD) image sensors for time-resolved imaging. The focus of the paper is on pixel architectures featuring small pixel size (<25 μm) and high fill factor (>20%) as a key enabling technology
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This paper reviews the state of the art of single-photon avalanche diode (SPAD) image sensors for time-resolved imaging. The focus of the paper is on pixel architectures featuring small pixel size (<25 μm) and high fill factor (>20%) as a key enabling technology for the successful implementation of high spatial resolution SPAD-based image sensors. A summary of the main CMOS SPAD implementations, their characteristics and integration challenges, is provided from the perspective of targeting large pixel arrays, where one of the key drivers is the spatial uniformity. The main analog techniques aimed at time-gated photon counting and photon timestamping suitable for compact and low-power pixels are critically discussed. The main features of these solutions are the adoption of analog counting techniques and time-to-analog conversion, in NMOS-only pixels. Reliable quantum-limited single-photon counting, self-referenced analog-to-digital conversion, time gating down to 0.75 ns and timestamping with 368 ps jitter are achieved. Full article
(This article belongs to the Special Issue Photon-Counting Image Sensors)
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Open AccessReview Photon Counting Imaging with an Electron-Bombarded Pixel Image Sensor
Sensors 2016, 16(5), 617; doi:10.3390/s16050617
Received: 27 January 2016 / Revised: 8 April 2016 / Accepted: 25 April 2016 / Published: 28 April 2016
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Abstract
Electron-bombarded pixel image sensors, where a single photoelectron is accelerated directly into a CCD or CMOS sensor, allow wide-field imaging at extremely low light levels as they are sensitive enough to detect single photons. This technology allows the detection of up to hundreds
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Electron-bombarded pixel image sensors, where a single photoelectron is accelerated directly into a CCD or CMOS sensor, allow wide-field imaging at extremely low light levels as they are sensitive enough to detect single photons. This technology allows the detection of up to hundreds or thousands of photon events per frame, depending on the sensor size, and photon event centroiding can be employed to recover resolution lost in the detection process. Unlike photon events from electron-multiplying sensors, the photon events from electron-bombarded sensors have a narrow, acceleration-voltage-dependent pulse height distribution. Thus a gain voltage sweep during exposure in an electron-bombarded sensor could allow photon arrival time determination from the pulse height with sub-frame exposure time resolution. We give a brief overview of our work with electron-bombarded pixel image sensor technology and recent developments in this field for single photon counting imaging, and examples of some applications. Full article
(This article belongs to the Special Issue Photon-Counting Image Sensors)
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Open AccessReview Geiger-Mode Avalanche Photodiode Arrays Integrated to All-Digital CMOS Circuits
Sensors 2016, 16(4), 495; doi:10.3390/s16040495
Received: 21 January 2016 / Revised: 21 March 2016 / Accepted: 1 April 2016 / Published: 8 April 2016
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Abstract
This article reviews MIT Lincoln Laboratory's work over the past 20 years to develop photon-sensitive image sensors based on arrays of silicon Geiger-mode avalanche photodiodes. Integration of these detectors to all-digital CMOS readout circuits enable exquisitely sensitive solid-state imagers for lidar, wavefront sensing,
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This article reviews MIT Lincoln Laboratory's work over the past 20 years to develop photon-sensitive image sensors based on arrays of silicon Geiger-mode avalanche photodiodes. Integration of these detectors to all-digital CMOS readout circuits enable exquisitely sensitive solid-state imagers for lidar, wavefront sensing, and passive imaging. Full article
(This article belongs to the Special Issue Photon-Counting Image Sensors)
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