Silicon Detector Technology Research Articles

Highly efficient visible and near-IR photon pair generation with thin-film lithium niobate

Efficient on-chip entangled photon pair generation at telecom wavelengths is an integral aspect of emerging quantum optical technologies, particularly for quantum communication and computing. However, moving to shorter wavelengths enables the use of more accessible silicon detector technology, and opens up applications in imaging and spectroscopy. Here, we present high brightness ((1.6 ± 0.3) × 109 pairs/s/mW/nm) visible–near-IR photon pair generation in a periodically poled lithium niobate nanophotonic waveguide. The degenerate spectrum of the photon pairs is centered at 811 nm with a bandwidth of 117 nm when pumped with a spectrally multimode laser diode. The measured on-chip source efficiency of (2.3 ± 0.5) × 1011 pairs/s/mW is on par with source efficiencies at telecom wavelengths and is also orders of magnitude higher than the efficiencies of other visible sources implemented in bulk crystal or diffused waveguide-based technologies. Further improvements in the brightness and efficiencies are possible by pumping the device with a single-frequency laser, which would also shrink the pair bandwidth. These results represent the shortest wavelength of photon pairs generated in a nanophotonic waveguide reported to date by nearly an octave.

Characterization of iLGADs using soft X-rays

Experiments at synchrotron radiation sources and X-ray Free-Electron Lasers in the soft X-ray energy range (250 eV–2 keV) stand to benefit from the adaptation of the hybrid silicon detector technology for low energy photons. Inverse Low Gain Avalanche Diode (iLGAD) sensors provide an internal gain, enhancing the signal-to-noise ratio and allowing single photon detection below 1 keV using hybrid detectors. In addition, an optimization of the entrance window of these sensors enhances their quantum efficiency (QE).In this work, the QE and the gain of a batch of different iLGAD diodes with optimized entrance windows were characterized using soft X-rays at the Surface/Interface:Microscopy beamline of the Swiss Light Source synchrotron. Above 250 eV, the QE is larger than 55% for all sensor variations, while the charge collection efficiency is close to 100%. The average gain depends on the gain layer design of the iLGADs and increases with photon energy. A fitting procedure is introduced to extract the multiplication factor as a function of the absorption depth of X-ray photons inside the sensors. In particular, the multiplication factors for electron- and hole-triggered avalanches are estimated, corresponding to photon absorption beyond or before the gain layer, respectively.

Utilizing broadband wavelength-division multiplexing capabilities of hollow-core fiber forquantum communications.

One of the major challenges in the deployment of quantum communications (QC) over solid-core silica optical fiber is the performance degradation due to the optical noise generated with co-propagating classical optical signals. To reduce the impact of the optical noise, research teams are turning to new and novel architectures of solid-core and hollow-core optical fiber. We studied the impact when co-propagating a single-photon level (850nm) and two classical optical signals (940nm and 1550nm) while utilizing a nested antiresonant nodeless fiber (NANF) with two low-loss windows. The 940nm signal was shown to impact the single-photon measurement due to the silicon detector technology implemented; however, multiplexing techniques and filtering could reduce the impact. The 1550nm signal was shown to have no detrimental impact. The results highlight that both high bandwidth optical traffic at 1550nm and a QC channel at 850nm could co-propagate without degradation to the QC channel.

Development of a CMOS pixel sensor prototype for the high hit rate CEPC vertex detector

The proposed Circular Electron Positron Collider (CEPC) imposes new challenges for the vertex detector in terms of material budget, spatial resolution, readout speed, and power consumption. It is necessary to design and construct the CEPC vertex detector with state-of-the-art silicon detector technologies. A dedicated CMOS Pixel Sensor chip, named TaichuPix, is being developed for the first 6-layer CEPC vertex detector prototype. The TaichuPix development is based on a fast in-pixel readout combined with a hit-driven architecture, which would be beneficial for the high hit rate. This work reports the requirements for the sensor and the design approach being followed to cope with it. Two small-scale prototypes (25 mm2) capable of achieving a hit rate up to 36 MHz/cm2, were designed in a 180 nm CMOS process. One of them, the TaichuPix-2 prototype was characterized with electrical and radioactive sources in the laboratory. The test results on the chip functionality and the pixel performance in terms of threshold and noise as well as the timing response are reported.

Phonon-mediated high-voltage detector with background rejection for low-mass dark matter and reactor coherent neutrino scattering experiments

We report the first demonstration of a phonon-mediated silicon detector technology that provides a primary phonon measurement in a low-voltage region, and a simultaneous indirect measurement of the ionization signal through Neganov–Trofimov–Luke amplification in a high voltage region, both in a monolithic crystal. We present characterization of charge and phonon transport between the two stages of the detector and the resulting background discrimination capability at low energies. This new detector technology has the potential to significantly enhance the sensitivity of dark matter and coherent neutrino scattering experiments beyond the capabilities of current technologies that have limited discrimination at low energies.

Effect on dark matter exclusion limits from new silicon photoelectric absorption measurements

Recent breakthroughs in cryogenic silicon detector technology allow for the observation of single electron-hole pairs released via particle interactions within the target material. This implies sensitivity to energy depositions as low as the smallest band gap, which is $\sim1.2$ eV for silicon, and therefore sensitivity to eV/$c^2$-scale bosonic dark matter and to thermal dark matter at masses below 100 MeV/$c^2$. Various interaction channels that can probe the lowest currently accessible masses in direct searches are related to standard photoelectric absorption. In any of these respective dark matter signal models any uncertainty on the photoelectric absorption cross section is propagated into the resulting exclusion limit or into the significance of a potential observation. Using first-time precision measurements of the photoelectric absorption cross section in silicon recently performed at Stanford University, this article examines the importance having accurate knowledge of this parameter at low energies and cryogenic temperatures for these dark matter searches.

Manufacturability and Stress Issues in 3D Silicon Detector Technology at IMB-CNM.

This paper provides an overview of 3D detectors fabrication technology developed in the clean room of the Microelectronics Institute of Barcelona (IMB-CNM). Emphasis is put on manufacturability, especially on stress and bow issues. Some of the technological solutions proposed at IMB-CNM to improve manufacturability are presented. Results and solutions from other research institutes are also mentioned. Analogy with through-silicon-via technology is drawn. This article aims at giving hints of the technology improvements implemented to upgrade from a R&D process to a mature technology.

Silicon pixel sensor R&D for the CLIC tracking detector

The physics aims at the proposed high-energy e^+e^− collider CLIC pose challenging demands on the performance of the detector system. Precise hit-time tagging, an excellent spatial resolutions, and a low mass are required for the vertex and tracking detectors. To meet these requirements, an all-silicon vertex and tracking detector system is foreseen, for which a broad R&D programme on a variety of novel silicon detector technologies is being pursued. For the ultra-low mass vertex detector, different hybrid technologies with innovative sensor concepts and interconnection techniques are explored. For the large-scale tracking detector, the focus of the R&D lies on monolithic HV-MAPS and HR-CMOS technologies. This contribution gives an overview of the ongoing activities with a focus on monolithic technologies for the CLIC tracking detector. Recent results from laboratory and test-beam measurement campaigns of the ATLASpix\\_Simple and the CLICTD sensor prototypes are presented.

Vertex and tracking detector R&D for CLIC

The physics goals at the proposed future Compact Linear Collider (CLIC) pose challenging demands on the performance of the detector system. Precise hit-time tagging with a few nanoseconds resolution is required for the vertex and tracking detectors, as well as a very low mass per layer combined with a single-plane spatial resolution of a few micrometres. To address these requirements, an all silicon vertex and tracking system is foreseen at CLIC. To this end, a broad R&D program on new silicon detector technologies is currently pursued. While the silicon pixel R&D for the CLIC vertex detector and tracker covers a wide range of various technologies and the development of different tools, this contribution is mainly focussed on the development of monolithic CMOS sensors with a small collection electrode.

Test beam measurements of an irradiated prototype pixel sensor designed for the CEPC vertex detector

The Circular Electron Positron Collider (CEPC) has been proposed as a Higgs factory to measure the properties of the Higgs boson with unprecedented precision and to guide the searches for new physics. To meet the stringent physics requirements, it is necessary to design and construct its vertex detector with the state-of-the-art silicon detector technologies. The first prototype CMOS pixel sensor, named JadePix-1, was developed for the CEPC vertex detector and its performance was already characterized with radioactive sources in laboratory. This prototype sensor was further characterized at the DESY test beam facility. Results are reported on charge collection, cluster size, position resolution and detection efficiency before and after the sensor samples exposed to neutron irradiation up to the fluence level of 10131 MeVneq∕cm2.

3D Detectors on Hydrogenated Amorphous Silicon for particle tracking in high radiation environment

The vertex detectors for the future hadronic colliders will operate under proton fluencies above 1016 p/cm2. Crystalline Silicon detector technology, up to now, has kept the pace of the increasing fluencies in the LHC era and it is still the prevalent vertex detector material for the present and for the immediate future. Looking ahead in time, an alternative solution for such a detector has to be found because for the future there is no guarantee that Crystalline Silicon will hold this challenge. For this reason the development of hydrogenated amorphous silicon vertex detectors based on 3D-technology have been proposed and the technological solutions in order to build these detectors are described in this paper.

Photon counting detector package based on InGaAs/InP avalanche structure for laser ranging applications.

Satellite Laser Ranging (SLR) is a well established space geodetic technique measuring the satellite distance, which implements time of flight. Up to now, second harmonic Nd:YAG laser pulses have been frequently used for range measurement, since the silicon detector technology allows us to detect single photon echoes reflected from satellites with required high detection probability, millimeter precision, and an acceptable dark count rate. On the other hand, the fundamental wavelength (1064 nm) provides a significantly better overall energy budget, but there were no suitable detectors available. More recently, the use of InGaAs/InP became feasible for developing single photon avalanche diodes, which exhibit high photon detection probability and acceptable timing resolution. Both these properties are important and allow the SLR measurement at the fundamental wavelength. In this Note, we report on construction and testing of a single photon detector package based on the InGaAs/InP diode optimized for the SLR measurement.

New trends in silicon detector technology

Modern detector science and technology has originated from High Energy Physics experiment needs in the '80's of the past century, based on the achievement and knowledge of the silicon industry of the time. The first segmented array of diodes (a microstrip sensor) was developed to track vertices at the NA11 experiment at the SPS accelerator at CERN (Geneva, CH) . During the following years, detector technology developed into a special branch of the huge silicon technology enterprise that has been arguably the biggest contributor to the evolution of most of the economical, social and scientific activities of mankind. If, and how, detector technology for science has kept the pace with the spectacular speed of evolution of mainstream silicon technology (namely, the microelectronics industry) is the object of this paper, that will also point out the special requirements of detectors for science and how these can be linked to modern microelectronics trends.

The high-energy particle package onboard CSES

The China Seismo-Electromagnetic Satellite (CSES) aims to monitor space electromagnetic fields, ionospheric plasma, high-energy charged particles and other features of the global space environment. The high-energy particle package (HEPP), which can effectively detect the energy spectrum, flux and pitch angle distribution of space electrons and protons, and soft X-ray emission from solar flares, is one of the main payloads of CSES. In this study, we designed, developed and calibrated the high-energy particle package and launched it into orbit with CSES. HEPP consists of the high-energy detector (HEPP-H), the low-energy detector (HEPP-L), and the solar X-ray monitor (HEPP-X). The three sub-detectors mainly use silicon detector and crystal calorimeter detection technology. Before launching, we calibrated the three sub-detectors in detail by using radiation source and accelerator beam. All the three sub-detectors have good energy linearity. After launching into orbit, the space energetic particles and X-ray distribution detected by HEPP are consistent with expectations. The performance indices of the detector reach the advanced level of the same kind of detector in the world. HEPP has a wide energy detection range, good energy resolution and high angular resolution ability for electrons and protons. It will play an important role in the study of space particle response and space physics of seismic activity.

Micrometer-resolution imaging using MÖNCH: towards G2-less grating interferometry.

MÖNCH is a 25 µm-pitch charge-integrating detector aimed at exploring the limits of current hybrid silicon detector technology. The small pixel size makes it ideal for high-resolution imaging. With an electronic noise of about 110 eV r.m.s., it opens new perspectives for many synchrotron applications where currently the detector is the limiting factor, e.g. inelastic X-ray scattering, Laue diffraction and soft X-ray or high-resolution color imaging. Due to the small pixel pitch, the charge cloud generated by absorbed X-rays is shared between neighboring pixels for most of the photons. Therefore, at low photon fluxes, interpolation algorithms can be applied to determine the absorption position of each photon with a resolution of the order of 1 µm. In this work, the characterization results of one of the MÖNCH prototypes are presented under low-flux conditions. A custom interpolation algorithm is described and applied to the data to obtain high-resolution images. Images obtained in grating interferometry experiments without the use of the absorption grating G2 are shown and discussed. Perspectives for the future developments of the MÖNCH detector are also presented.

Angular independent silicon detector for dosimetry in external beam radiotherapy.

In this work, the "edgeless" silicon detector technology is investigated, in combination with an innovative packaging solution, to manufacture silicon detectors with negligible angular response. The new diode is also characterized as a dosimeter for radiotherapy with the aim to verify its suitability as a single detector for in vivo dosimetry as well as large area 2D array that does not require angular correction to their response. For the characterisation of the "edgeless-drop-in" detector technology, a set of samples have been manufactured with different sensitive areas (1 × 1 and 0.5 × 0.5 mm(2)) and different thicknesses (0.1 and 0.5 mm) in four different combinations of top and peripheral p-n junction fabricated on p-type and n-type silicon substrates. The diode probes were tested in terms of percentage depth dose (PDD), dose rate, and linearity and compared to ion chambers. Measurements of the output factor have been compared to film. The angular response of the diodes probes has been tested in a cylindrical PMMA phantom, rotated with bidirectional accuracy of 0.25° under 10 × 10 cm(2) 6 MV Linac photon beam. The radiation hardness has been investigated as well as the effect of radiation damage on the angular and dose rate response of the diode probes when irradiated with photons from a Co-60 gamma source up to dose of 40 kGy. The PDDs measured by the edgeless detectors show an agreement with the data obtained using ion chambers within ±2%. The output factor measured with the smallest area edgeless diodes (0.5 × 0.5 mm(2)-0.1 and 0.5 mm thick) matches EBT3 film to within 2% for square field size from 10 to 0.5 cm side equivalent distance. The dose rate dependence in a dose per pulse range of 0.9 × 10(-5)-2.7 × 10(-4) Gy/pulse was less than -7% and +300% for diodes fabricated on p-type and n-type substrates, respectively. The edgeless diodes fabricated on the p-type substrate demonstrated degradation of the response as a function of the irradiation dose within 5%-15%, while diodes on the n-type substrate show a variation of approximately 30% after 40 kGy. The angular response of all probes is minimal (within 2%) but the N on N and P on P configurations show the best performances with an angular dependence of ±1.0% between 0° and 180° in the transversal direction. In this configuration, the space charge region of the passive diode extends from the behind and sidewall toward the anode on the top providing beneficial electric field distribution in the peripheral area of the diode. Such performance has also been tested after irradiation by Co-60 up to 40 kGy with no measurable change in angular response. A new edgeless-drop-in silicon diode fabrication and packaging technology has been used to develop detectors that show no significant angular dependence in their response for dosimetry in radiation therapy. From the characterisation of the diodes, proposed in a wide range of different geometries and configurations, the authors recommend the P-on-P detectors in conjunction with "drop in" packaging technology as the candidate for further development as single diode probe or 2D diode array for dosimetry in radiotherapy.

Experience from the construction and operation of the STAR PXL detector

A new silicon based vertex detector called the Heavy Flavor Tracker (HFT) was installed at the Soleniodal Tracker At RHIC (STAR) experiment for the Relativistic Heavy Ion Collider (RHIC) 2014 heavy ion run to improve the vertex resolution and extend the measurement capabilities of STAR in the heavy flavor domain. The HFT consists of four concentric cylinders around the STAR interaction point composed of three different silicon detector technologies based on strips, pads and for the first time in an accelerator experiment CMOS monolithic active pixels (MAPS) . The two innermost layers at a radius of 2.8 cm and 8 cm from the beam line are constructed with 400 high resolution MAPS sensors arranged in 10-sensor ladders mounted on 10 thin carbon fiber sectors giving a total silicon area of 0.16 m2. Each sensor consists of a pixel array of nearly 1 million pixels with a pitch of 20.7 μm with column-level discriminators, zero-suppression circuitry and output buffer memory integrated into one silicon die with a sensitive area of ∼ 3.8 cm2. The pixel (PXL) detector has a low power dissipation of 170 mW/cm2, which allows air cooling. This results in a global material budget of 0.5% radiation length per layer for detector used in this run. A novel mechanical approach to detector insertion allows for the installation and integration of the pixel sub detector within a 12 hour period during an on-going STAR run. The detector specifications, experience from the construction and operation, lessons learned and initial measurements of the PXL performance in the 200 GeV Au-Au run will be presented.

Fabrication and characterization of silicon based thermal neutron detector with hot wire chemical vapor deposited boron carbide converter

In order to utilize the well established silicon detector technology for neutron detection application, a silicon based thermal neutron detector was fabricated by integrating a thin boron carbide layer as a neutron converter with a silicon PIN detector. Hot wire chemical vapor deposition (HWCVD), which is a low cost, low temperature process for deposition of thin films with precise thickness was explored as a technique for direct deposition of a boron carbide layer over the metalized front surface of the detector chip. The presence of B-C bonding and 10B isotope in the boron carbide film were confirmed by Fourier transform infrared spectroscopy and secondary ion mass spectrometry respectively. The deposition of HWCVD boron carbide layer being a low temperature process was observed not to cause degradation of the PIN detector. The response of the detector with 0.2µm and 0.5µm thick boron carbide layer was examined in a nuclear reactor. The pulse height spectrum shows evidence of thermal neutron response with signature of (n, α) reaction. The results presented in this article indicate that HWCVD boron carbide deposition technique would be suitable for low cost industrial fabrication of PIN based single element or 1D/2D position sensitive thermal neutron detectors.

New source and detector technology for the realization of photometric units

The production of incandescent light bulbs is bound to end, as incandescent lighting is being phased out globally in favour of more energy-efficient and sustainable solutions. Temporally stable light-emitting diodes (LEDs) are potential candidates to replace incandescent lamps as photometric source standards. However, traditional V(λ) filter based photometers may have large uncertainty when LEDs are measured instead of incandescent lamps. This is due to the narrow and complicated spectra of LEDs. When the spectra of LEDs are limited to the visible wavelength range, new silicon detector technology can be advantageously exploited in photometry. We present a novel method—based on the recently introduced Predictable Quantum Efficient Detector (PQED)—for the realization of photometric units which completely eliminates the need to use V(λ) filters. Instead, the photometric weighting is taken into account numerically by measuring the relative spectral irradiance. The illuminance values of a blue and a red LED were determined using the new method and a conventional reference photometer. The values obtained by the two methods deviated from each other by −0.06% and 0.48% for the blue and red LED, respectively. The PQED-based values have much lower standard uncertainty (0.17% to 0.18%) than the uncertainty of the values based on the conventional photometer (0.46% to 0.51%).

3D Radiation Detectors: Charge Collection Characterisation and Applicability of Technology for Microdosimetry

A study of charge collection in SINTEF 3D active edge silicon detectors was carried out at ANSTO using Ion Beam Induced Charge (IBIC) technique. An IBIC study has shown that several different geometries of 3D detectors have full depletion under low applied bias. The effect of fast neutron and gamma radiation on their charge collection efficiency was also investigated. A 3D active edge silicon detector technology has demonstrated extremely promising performance for application of the 3D Sensitive Volumes (SVs) fabrication methods to SOI microdosimetry.