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In this paper, we present a honeycomb structure to maximize the edge-length in the detector and therefore enhance the detector responsivity in the blue region of the spectrum. A layout of a prototype honeycomb detector was designed and fabricated on a silicon wafer using a standard CMOS process. Based on our measured spectral response, the honeycomb structure improves the photocurrent in blue by about...
We have developed silicon (Si) strip photon counting detectors for modalities used in clinical breast imaging including mammography, tomosynthesis, computed tomography, and lump imaging in the operating room. Typically, x-ray integrating detectors based on scintillating cesium iodide CsI(Tl) or amorphous selenium (a-Se) are used in most commercial systems. Recently, mammography instrumentation has...
Dual-junction solar cells consisting of rear-heterojunction GaInP top cells and back-junction, back-contacted crystalline Si bottom cells were fabricated and characterized. Our calculations show that theoretical efficiencies up to 38.9% can be achieved with Si-based tandem devices. In our experiments, the two subcells were fabricated separately and stacked with an index matching fluid. In contrast...
The paper describes a CMOS Integrated Circuit designed for interfacing a Silicon Photomultiplier (SiPM) in UMC 180 nm technology. It features a full signal processing architecture containing Pole-Zero Cancellation (PZC) circuit, Peak Detector and Hold circuit and Comparators which one of main purposes is the coincidence recognition. Front-end electronics consists of two separate channels one for each...
M/Semi-insulating (SI) GaAs/M diodes with novel Mg-based metallization are investigated using current-voltage measurement, α-particle and photon detection. An anomalous decrease of the reverse current and peculiar photon spectra has been observed with such contact explainable by a strong electron accumulation due to the creation of a quasi-degenerate region at the Mg/SI-GaAs interface.
Many applications, particularly in the medical and bio-medical fields, require highly sensitive detectors in the short wavelength range (blue and below); so far there have been few commercially available avalanche photodetectors with adequate performance to satisfy demands of such applications. We have developed a new silicon reach-through avalanche photodiode (RAPD) operating in the blue wavelength...
In this paper we present the increased light emission for Si p-i-n light emitting diodes (LED) by geometrical scaling of the injector size for p- and n-type carriers. TCAD simulations and electrical and optical characteristics of our realized devices support our findings. Reducing the injector size decreases the diffusion current: therefore, for a particular on current, the pn-product, and hence the...
As development phases became shorter, fast defect characterization is highly important. In addition, new chemicals involved in sub 28nm semiconductor processes introduce new types of defects. The variety of defect types complicates defect root cause analysis, so that image based defect analysis is limited, and defect material information becomes more important. Thus elemental analysis of defects in...
Transparent silicon can lead to increased conversion efficiency in a multi-junction assembly by transmitting near and below band gap energy photons to a lower band gap solar cell. With semi-empirical calculations from Gray et.al. potential efficiency gain from a lower band gap solar cell can be 4.9% absolute under concentration. The present work analyzes a 4-wire tandem system consisting of mono-crystalline...
Ge p-i-n photodiodes integrated with Si variable optical attenuators exhibit low dark current of 60 nA and high responsivity of 0.85 A/W at -1 V. These Ge photodiodes have potential for monolithic integration with other Si photonic components.
This paper reviews recent experimental confirmations that the intrinsic radiation robustness of commercial CMOS technologies naturally improves with the down-scaling. When additionally using innovative design techniques, it becomes now possible to assure that performance and radiation-hardness are both met. An illustration is given with an original nano-power and radiation-hardened 8 Mb SRAM designed...
The nowadays quite indispensable enhancement of PV conversion efficiency cannot be obtained without new mechanisms. The most useful of these mechanisms has to appear in the front face of the device, i.e. in the emitter, so as to allow exploitation of the energetic photons of the solar spectrum. Such an improvement can be realized through a multistage PV conversion starting by primary generation (photon...
We show that SAGM InGaAs/InP Avalanche Photodiodes, cooled at 200K, detect the arrival time of single photons with nanosecond resolution. Hole trapping at the heterointerface impairs the performance of presently available devices. However, a proper design of the structure for low temperature operation is expected to improve their timing performance well below the nanosecond limit.
We demonstrate for the first time the capability of commercially available Ge-APDs to achieve single photon sensitivity and sub-nanosecond time resolution at 77K. The selection procedure of the samples both with a curve tracer and in pulsed operation is described in detail. Further improvements of the timing performance can be obtained by a suitable design of the devices.
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