Silicon Avalanche Photodiode Research Articles

XNAP: a hybrid pixel detector with nanosecond resolution for time resolved synchrotron radiation studies

The XNAP collaboration is constructing a hybrid pixel X-ray detector based on a monolithic silicon avalanche photodiode (APD) sensor array aiming at applications in synchrotron radiation facilities. The 2D detector is capable of identifying which individual electron bunch produces each detected X-ray photon, even when the storage ring operates in multibunch filling modes. This instrument is intended to be used in X-ray Photon Correlation Spectroscopy and Nuclear Resonance experiments and serve as a demonstrator for various kind of time resolved diffraction and scattering applications as well as a very high count rate device. The detector is a 1 kilopixel device with 280 μm pitch that implements both counting mode up to MHz frame rates and event-by-event readout with sub-nanosecond time resolution. The paper describes the detector design and some results obtained with small 4×4 pixel prototypes that have been built and measured to make and validate the most critical choices for the final detector.

Efficient premature edge breakdown prevention in SiAPD fabrication using the standard CMOS process

The effects of premature edge breakdown (PEB) and available PEB prevention (PEBP) techniques in silicon avalanche photodiode fabrication using the standard complementary metal–oxide–semiconductor (CMOS) process are scrutinized in this paper. Impact of device simulation and its induced impacts on fabrication are addressed based on our design, simulation and fabrication experiences. Three most common PEBP techniques are implemented followed by a systematic study aimed at miniaturization, while optimizing the overall performance. The p-well-, p-sub- and n-well-based PEBP techniques are evaluated and compared based on simulation and fabrication results using the standard CMOS process. The results demonstrate that the n-well guard ring offers the most efficient PEBP technique. This technique offers a high-gain (∼800), low-noise dark current rate (DCR = 40 Hz), high detection efficiency (70%) avalanche photodiode with a higher functionality probability.

Influence of neutrons on signal fluctuations for APD structures

Silicon Avalanche Photo-diodes (APDs) working in proportional were chosen as a readout device for the PbWO4 crystals in the barrel of the CMS Electromagnetic Calorimeter (ECAL). During 10 years of operation, the CMS ECAL will be exposed to 2×1013neutrons/cm2 under a severe radiation environment. In this study, we studied on the effect of photo-statistical fluctuations from those of neutrons by using Geant4 toolkit.

SiPM based readout system for [formula omitted] crystals

Silicon PhotoMultipliers (SiPMs) consist of a matrix of small passively quenched silicon avalanche photodiodes operated in limited Geiger-mode (GM-APDs) and read out in parallel from a common output node. Each pixel (with a typical size in the 20–100μm range) gives the same current response when hit by a photon; the SiPM output signal is the sum of the signals of all the pixels, which depends on the light intensity. The main advantages of SiPMs with respect to photomultiplier tubes (PMTs) are essentially the small dimensions, the insensitivity to magnetic fields and a low bias voltage. This contribution presents the performance of a SiPM based readout system for crystal calorimeters developed in the framework of the FACTOR/TWICE collaboration. The SiPM used for the test is a new device produced by FBK-irst which consists in a matrix of four sensors embedded in the same silicon substrate, called QUAD. The SiPM has been coupled to a lead tungstate crystal, an early-prototype version of the crystals developed for the electromagnetic calorimeter of the CMS experiment. New tests are foreseen using a complete module consisting of nine crystals, each one readout by two QUADs.

A study of the autocorrelation function of the pulse flow of one-quantum avalanche photodiodes

Studies of autocorrelation functions of pulse flows from silicon avalanche photodiodes, which operate in the one-quantum detection mode, were performed in the photon counting mode. The influence of afterpulses and the dead-time effect on the behavior of the autocorrelation function was determined.

A detector insert based on continuous scintillators for hybrid MR–PET imaging of the human brain

We are developing a positron emission tomography (PET) insert for existing magnetic resonance (MR) equipment, aiming at hybrid MR–PET imaging. Our detector block design is based on trapezoid-shaped LYSO:Ce monolithic scintillators coupled to magnetically compatible Hamamatsu S8550-02 silicon avalanche photodiode (APD) matrices with a dedicated ASIC front-end readout from GammaMedica-Ideas (Fornebu, Norway). The detectors are position sensitive, capable of determining the incidence point of 511keV gammas with an intrinsic spatial resolution on the order of 2mm by means of supervised learning neural-network (NN) algorithms. These algorithms, apart from providing continuous coordinates, are also intrinsically corrected for depth of interaction effects and thus parallax-free. Recently we have implemented an advanced prototype featuring two heads with four detector blocks each and final front-end and readout electronics, improving the spatial resolution of reconstructed point source images down to 1.7mm full width at half maximum (FWHM). Presently we are carrying out operational tests of components and systems under magnetic fields using a 3 T MR scanner. In this paper we present a description of our project, a summary of the results obtained with laboratory prototypes, and the strategy to build and install the complete system at the nuclear medicine department of a collaborating hospital.

Hydrogen Redistribution and Performance Improvement of Silicon Avalanche Photodiode by Low-Temperature Annealing

We report the performance improvement of the silicon avalanche photodiode (APD) for electron detection by annealing. It was found that the dark current is reduced and that the gain and energy resolution are improved by annealing at 500 K for 10 h. By means of the nuclear reaction analysis, the depth distribution of hydrogen in APD was measured before and after annealing. The hydrogen concentration in the near-surface region was significantly increased by annealing. We discuss that passivation of the impurity and/or defect levels by hydrogen atoms is a possible reason for the performance improvement of the photodiode.

Single-photon emission from electrically driven InP quantum dots epitaxially grown on CMOS-compatible Si(001)

The heteroepitaxy of III–V semiconductors on silicon is a promising approach for making silicon a photonic platform. Mismatches in material properties, however, present a major challenge, leading to high defect densities in the epitaxial layers and adversely affecting radiative recombination processes. However, nanostructures, such as quantum dots, have been found to grow defect-free even in a suboptimal environment. Here we present the first realization of indium phosphide quantum dots on exactly oriented Si(001), grown by metal–organic vapour-phase epitaxy. We report electrically driven single-photon emission in the red spectral region, meeting the wavelength range of silicon avalanche photodiodes’ highest detection efficiency.

Design of a high sensitivity emitter-detector avalanche photodiode imager using very high transmittance, back-illuminated, silicon-on-sapphire

We present a detailed design study for a novel solid-state focal plane array of silicon avalanche photodiodes (APDs) using an advanced silicon-on-sapphire substrate incorporating an antireflective bilayer consisting of crystalline aluminum nitride (AlN) and amorphous, non-stoichiometric, silicon rich, silicon nitride (a-SiNX<1.33) between the silicon and sapphire. The substrate supports electrical and optical integration of a nearly 100% quantum efficiency, silicon APD capable of operating with wide dynamic range in dual linear or Geiger-mode, with a gallium nitride (GaN) laser diode in each pixel. The APD device and epitaxially grown GaN laser are fabricated within a crystallographically etched silicon mesa. The high resolution 27 μm emitter-detector pixel design enables single photon sensitive, solid-state focal plane arrays (FPAs), with passive and active imaging capability in a single FPA. The square 27 μm emitter-detector pixel achieves SNR>10 in active detection mode for Lambert surfaces at 20,000 m.

Expected radiation damage of reverse-type APDs for the Astro-H mission

Scheduled for launch in 2014, Astro-H is the sixth Japanese X-ray astronomy satellite mission. More than 60 silicon avalanche photodiodes (Si-APDs; hereafter APDs)will be used to read out BGO scintillators, which are implemented to generate a veto signal to reduce background contamination for the hard X-ray imager (HXI) and a soft gamma-ray detector (SGD). To date, however, APDs have rarely been used in space experiments. Moreover, strict environmental tests are necessary to guarantee APD performance for missions expected to extend beyond five years. The radiation hardness of APDs, as for most semiconductors, is particularly crucial, since radiation in the space environment is severe. In this paper, we present the results of radiation tests conducted on reverse-type APDs (provided by Hamamatsu Photonics) irradiated by gamma rays (60Co) and 150 MeV protons. We show that, even under the same 100 Gy dose, high energy protons can cause displacement (bulk) damage in the depletion region and possibly change the activation energy, whereas gamma-ray irradiation is less prone to cause damage, because ionization damage dominates only the surface region.We also present quantitative guidance on how to estimate APD noise deterioration over a range of temperatures and radiation doses. As a practical example, we discuss the expected degradation of the BGO energy threshold for the generation of veto signals, following several years of Astro-H operation in Low Earth Orbit (LEO), and directly compare it to experimental results obtained using a small BGO crystal.

Longitudinal density monitor for the LHC

The longitudinal density monitor (LDM) is primarily intended for the measurement of the particle population in nominally empty rf buckets. These so-called satellite or ghost bunches can cause problems for machine protection as well as influencing the luminosity calibration of the LHC. The high dynamic range of the system allows measurement of ghost bunches with as little as 0.01% of the main bunch population at the same time as characterization of the main bunches. The LDM is a single-photon counting system using visible synchrotron light. The photon detector is a silicon avalanche photodiode operated in Geiger mode, which allows the longitudinal distribution of the LHC beams to be measured with a resolution of 90 ps. Results from the LDM are presented, including a proposed method for constructing a 3-dimensional beam density map by scanning the LDM sensor in the transverse plane. In addition, we present a scheme to improve the sensitivity of the system by using an optical switching technique.

Achievement of the Novel Lidar Visibility Measurement System

Atmospheric visibility is close to the transportation safety. In order to get accurate atmospheric visibility, according to atmosphere backscattering theory, a novel visibility measurement system is designed. The system adopts many modular devices such as semiconductor laser, silicon avalanche photodiode detector, multi channel photon counting card, embedded computer and so on. Where embedded computer is the core of the system, to realize system timing control, visibility inversion and information display. Finally, the objective and convenient measurement of atmospheric horizontal visibility and slant visibility are achieved. Outfield comparison experiments show that in low visibility weather conditions, the system obtains high measurement accuracy, which has high practical value and wonderful development prospect.

A nanosecond gate-mode-driven silicon avalanche photodiode and its application to measuring fluorescence lifetimes of Ce-doped YAG ceramics

We propose a silicon avalanche photodiode (Si-APD)-based boxcar-integrator, in which the Si-APD is driven in the gate mode. In the gate mode, by setting the direct current reverse-bias voltage Vr applied to the APD to below its breakdown voltage Vb, we superimpose a gate pulse of amplitude Vg on Vr so that the total voltage is nearly equal to Vb, but does not exceed it, i.e. Vr + Vg < Vb. In this case, the instantaneous current multiplication factor Mi of the APD is noticeably enhanced, especially when the duration of the gate pulse tw is reduced to the nanosecond scale. Because the gated Si-APD plays the role of a sampling unit as well as that of a photodetector for the repeatable signal light incident on the APD, in principle, the proposed scheme has an advantage in terms of the measured signal-to-noise ratio (SNR). To demonstrate the usefulness of the scheme, we have measured the fluorescence lifetimes of cerium-doped yttrium–aluminum–garnet (Ce:YAG) ceramics where the concentration of Ce is varied in steps.

Practical photon number detection with electric field-modulated silicon avalanche photodiodes

Low-noise single-photon detection is a prerequisite for quantum information processing using photonic qubits. In particular, detectors that are able to accurately resolve the number of photons in an incident light pulse will find application in functions such as quantum teleportation and linear optics quantum computing. More generally, such a detector will allow the advantages of quantum light detection to be extended to stronger optical signals, permitting optical measurements limited only by fluctuations in the photon number of the source. Here we demonstrate a practical high-speed device, which allows the signals arising from multiple photon-induced avalanches to be precisely discriminated. We use a type of silicon avalanche photodiode in which the lateral electric field profile is strongly modulated in order to realize a spatially multiplexed detector. Clearly discerned multiphoton signals are obtained by applying sub-nanosecond voltage gates in order to restrict the detector current.

Fully On-Chip Integrated Photodetector Front-End Dedicated to Real-Time Portable Optical Brain Imaging

Optical brain imaging using functional near infra-red spectroscopy (fNIRS) offers a portable and noninvasive tool for monitoring of blood oxygenation. In this paper we have introduced a new miniaturized photodetector front-end on achip to be applied in a portable fNIRS system. It includes silicon avalanche photodiodes (SiAPD), Transimpedance amplifier (TIA) front-end and Quench-Reset circuitry to operate in both linear and Geiger modes. So it can be applied for both continuous-wave fNIRS (CW-fNIRS) and also single-photon counting. Proposed SiAPD exhibits high-avalanche gain (>100), low-breakdown voltage ( V) and high photon detection efficiency accompanying with low dark count rates. The proposed TIA front-end offer a low power consumption ( mW), high-transimpedance gain (up to 250 MV/A), tunable bandwidth (1 kHz - 1 GHz) and very low input and output noise (~few fA/√Hz and few μV/√Hz). The Geiger-mode photon counting front-end also exhibits a controllable hold-off and rest time with an ultra fast quench-reset time (few ns). This integrated system has been implemented using submicron (0.35 μm) standard CMOS technology.

Experimental tests of the trigger prototype for the AMADEUS experiment based on Sci-Fi read by MPPC

The Multi-Pixel Photon Counter (MPPC) detectors consist of hundreds of micro silicon Avalanche PhotoDiodes (APD) working in Geiger mode. The high gain and the small dimensions typical of these devices, together with their good performances in magnetic field, make them ideal readout devices for scintillating fibers as trigger detectors in particle and nuclear physics experiments like AMADEUS, where such a system is planned to be used to trigger on charged kaons. A prototype setup for this trigger system, consisting of 5 scintillating fibers readout by 10 MPPCs, was built and tested in laboratory and mounted inside the DAΦNE collider at LNF-Frascati to measure the back-to-back K+K− pairs emitted in the Φ-decay processes. The ad hoc readout electronics was designed and realized at Laboratori Nazionali di Frascati (INFN). A 64 channels setup, with a new dedicated electronics, was then built and characterized in the laboratory. The results of the tests are presented and discussed.

Polarisation dependence of two-photon absorption generated by band-limited amplified spontaneous emission noise in silicon avalanche photodiodes

Two-photon absorption (TPA) generated by unpolarised band-limited amplified spontaneous emission (BL-ASE) noise is found to be within 5% of that generated by circularly polarised BL-ASE noise for silicon-based devices. A simple formula that describes the TPA generated by partially polarised BL-ASE noise as a function of material dichroism is given and verified experimentally.

A Silicon Balanced Subharmonic Optoelectronic Mixer for 60-GHz Fiber-Wireless Downlink Application

We demonstrate a 60-GHz fiber-wireless downlink using a balanced subharmonic optoelectronic mixer based on a silicon avalanche photodiode (APD) pair fabricated with standard 0.25-μm bipolar complementary metal-oxide-semiconductor technology. Conversion efficiency of this new type of optoelectronic mixer is 11 dB better than that of the previously reported single APD mixer. We achieve downlink transmission of 25-Mb/s 32 quadrature-amplitude modulation data with the minimum error-vector magnitude of 2.4%.

Mie lidar observations of lower tropospheric aerosols and clouds

Mie lidar system is developed at Laser Science and Technology Centre, Delhi (28.38°N, 77.12°E) by using minimal number of commercially available off-the-shelf components. Neodymium Yttrium Aluminum Garnet (Nd:YAG) laser operating at 1064 nm with variable pulse energies between 25 and 400 mJ with 10 Hz repetition rate and 7 ns pulse duration is used as a transmitter and off-axis CASSEGRAIN telescope with 100 mm diameter as a receiver. Silicon avalanche photodiode (Si-APD) module with built-in preamplifier and front-end optics is used as detector. This system has been developed for the studies of lower tropospheric aerosols and clouds. Some experiments have been conducted using this set up and preliminary results are discussed. The characteristics of backscattered signals for various transmitter pulse energies are also studied. Atmospheric aerosol extinction coefficient values are calculated using Klett lidar inversion algorithm. The extinction coefficient, in general, falls with range in the lower troposphere and the values lie typically in the range 7.5 × 10 −5 m −1 to 1.12 × 10 −4 m −1 in the absence of any cloud whereas this value shoots maximum up to 1.267 × 10 −3 m −1 (peak extinction) in the presence of clouds.

Ultra-low noise single-photon detector based on Si avalanche photodiode

We report operation and characterization of a lab-assembled single-photon detector based on commercial silicon avalanche photodiodes (PerkinElmer C30902SH, C30921SH). Dark count rate as low as 5 Hz was achieved by cooling the photodiodes down to -80 °C. While afterpulsing increased as the photodiode temperature was decreased, total afterpulse probability did not become significant due to detector's relatively long deadtime in a passively-quenched scheme. We measured photon detection efficiency >50% at 806 nm.