Search

The fabrication of silicon shallow junction photodiodes is a relevant topic for the detection of blue and near ultraviolet weak photon fluxes. In this paper we present a simple model to calculate the Quantum Detection Efficiency (QDE) of a Geiger Mode Avalanche Photodiode (GMAP) as a function of the dead layer thickness above the junction depletion layer. A comparison between calculated and experimental data is also presented. Moreover, by using the same model, an analysis of the QDE at 420 nm wavelength of conventional GMAPs based on shallow [N.sup.+]--P and [P.sup.+]--N junctions is given. Index Terms--Avalanche triggering probability, dead layer, Geiger mode avalanche photodiode, quantum detection efficiency, silicon photomultiplier.

The article examines the results of the charge and time characterization of a novel 100-channel silicon photomultiplier (SiPM). The charge measurement results show that SiPM can distinguish up to approximately 45 photons at room temperature and is able to achieve a time shift as a function of the intensity of the laser due to the operating principle of a gain-switching diode laser.

The article examines the results of the noise characterization of a novel 100-channel silicon photomultiplier. This device can be used to for the detection of very weak light pulses down to single photons and at a fixed temperature the noise behavior is reproducible which makes straightforward corrections due to dead-time and random noise pulse contamination possible.

This work is devoted to the analysis of [gamma]-ray effects on the behavior of bipolar junction transistors belonging to a silicon on insulator technology. Such a process is currently being investigated in order to assess its suitability for use in radiation-resistant applications, namely in the design of readout electronics for radiation detectors in high energy physics experiments and for operation in the space environment. Possible sensitivity to low dose-rate was tested by exposing the devices to [gamma]-ray sources with different activities. High dose rate irradiations were performed with the devices biased in different operating regions in order to evaluate the effects of bias conditions on the device sensitivity to radiation. Radiation tolerant, low noise design of charge preamplifiers is discussed in the last section of the paper, on the basis of the results relevant to single device characterization. Index Terms--BiCMOS process, bipolar transistor, ionization damage, silicon on insulator, [gamma]-rays.

This paper is concerned with the analysis of the noise properties of NPN bipolar junction transistors fabricated in a monolithic technology. Such devices are part of a BiCMOS silicon on insulator process, whose suitability for radiation hard applications is being evaluated. A thorough noise characterization, including series and parallel contribution measurements, was performed in view of the design of high-speed analog front-end electronics for radiation detectors. For this purpose, a method for optimizing the noise performances of charge measuring systems has been applied to the experimental data from single device characterization. Index Terms--Bipolar transistors, front-end electronics, parallel noise, series noise, spreading resistance.

A single photon avalanche detector (SPAD) in planar technology is described and discussd.

Featured Application: System suitable for human brain imaging (fNIRS, DOT). We built a fiber-less prototype of an optical system with 156 channels each one consisting of an optode made of a silicon photomultiplier (SiPM) and a pair of light emitting diodes (LEDs) operating at 700 nm and 830 nm. The system uses functional near-infrared spectroscopy (fNIRS) and diffuse optical tomography (DOT) imaging of the cortical activity of the human brain at frequencies above 1 Hz. In this paper, we discuss testing and system optimization performed through measurements on a multi-layered optical phantom with mechanically movable parts that simulate near-infrared light scattering inhomogeneities. The baseline optical characteristics of the phantom are carefully characterized and compared to those of human tissues. Here we discuss several technical aspects of the system development, such as LED light output drift and its possible compensation, SiPM linearity, corrections of channel signal differences, and signal-to-noise ratio (SNR). We implement an imaging algorithm that investigates large phantom regions. Thanks to the use of SiPMs, very large source-to-detector distances are acquired with a high SNR and 2 Hz time resolution. The overall results demonstrate the high potentialities of a system based on SiPMs for fNIRS/DOT human brain imaging applications. [ABSTRACT FROM AUTHOR]

This work is devoted to the analysis of γ-ray effects on the behavior of bipolar junction transistors belonging to a silicon on insulator technology. Such a process is currently being investigated in order to assess its suitability for use in radiation-resistant applications, namely in the design of readout electronics for radiation detectors in high energy physics experiments and for operation in the space environment. Possible sensitivity to low dose-rate was tested by exposing the devices to γ-ray sources with different activities. High dose rate irradiations were performed with the devices biased in different operating regions in order to evaluate the effects of bias conditions on the device sensitivity to radiation. Radiation tolerant, low noise design of charge preamplifiers is discussed in the last section of the paper, on the basis of the results relevant to single device characterization. [ABSTRACT FROM AUTHOR]