G. Condorelli

Highly Efficient Low Reverse Biased 4H-SiC Schottky Photodiodes for UV-Light Detection

Ultraviolet light detection has a wide range of scientific and industrial applications. In particular, SiC photodiodes have been proposed because of their robustness even in harsh environments, high quantum efficiency but excellent visible blindness, very low dark current, and high speed. Here, we report on the electrical and optical performances of high efficient large area 4 H-SiC Schottky photodiodes working in the photovoltaic regime. We demonstrate that the high signal-to-noise ratio along with the low operating reverse voltage in spite of the large sensitive area makes them suitable in low power consumption applications requiring high sensitivity down to 250 nm.

Characterization of a Novel 100-Channel Silicon Photomultiplier—Part I: Noise

In this paper, we present the results of the first noise characterization performed on our novel 100-channel silicon photomultiplier. We have improved our previous single-photon avalanche photodiode technology in order to set up a working device with outstanding features in terms of single-photon resolving power up to R = 45, timing resolution down to 100 ps, and photon-detection efficiency of 14% at 420 nm. Tests were performed, and features were measured, as a function of the bias voltage and of the incident photon flux. A dedicated data-analysis procedure was developed that allows one to extract at once the relevant parameters and quantify the noise.

Characterization of a Novel 100-Channel Silicon Photomultiplier—Part II: Charge and Time

In this paper, we present the results of the charge and time characterization performed on our novel 100-channel silicon photomultiplier. We have improved our previous single-photon-avalanche-diode technology in order to set up a working device with outstanding features in terms of single-photon resolving power up to R = 45, a timing resolution down to 100 ps, and photon-detection efficiency of 14% at 420 nm. Tests were performed, and features were measured as a function of the bias voltage and of the incident photon flux. A dedicated data analysis procedure was developed that allows to extract at once the relevant parameters from the amplitude spectra and to determine the timing features.

Arrays of Geiger mode avalanche photodiodes

Following our previous work which has led us to fabricate single pixels of geiger mode avalanche photodiodes (GMAPs), we present in this letter the results regarding the fabrication and characterization of a bidimensional array of GMAPs. Low dark count rates and very good uniformity over the sensor are reported. High quantum efficiency in the visible range has been measured. Measurements indicate that not all the nominal active area is effectively sensitive. We have some preliminary evidence that no crosstalk effects are present in our device. Notwithstanding this, in view of a near future shrinking of all dead regions, an optical trench process has been developed and is illustrated here. Possible future trends are highlighted

Characterization of detectors for the Italian Astronomical Quantum Photometer Project

In the framework of a national collaboration to bring Quantum Optics concepts to Astronomy, we are involved in finding suitable detectors for this novel application. At ‘INAF Osservatorio Astrofisico di Catania’ and ‘INFN – Laboratori Nazionali del Sud’ laboratories, measurements of electro-optical parameters, such as photon detection efficiency (PDE), linearity, dark counts and after pulsing probability, as well as of timing resolution, have been carried out. These measurements have been done on silicon detectors, such as single photon avalanche diode (SPAD) (both single element and array), and silicon photon multiplier (SiPM), operating in the photon counting regime.

Structure of the oxide damage under progressive breakdown

Abstract The I–V characteristics of ultra-thin gate oxides under progressive breakdown (BD) show a common behavior, indicative of well-defined general physical features of the BD spot. Transmission electron microscopy (TEM) observations give some hints about this structure and on this basis we propose a physical model of the post-BD current, which is in good agreement with data.

Silicon Photomultipliers for nuclear medical imaging applications

In this contribution we present the results of the first morphological and electro-optical characterization of Silicon Photomultipliers (SiPM) for nuclear medical imaging applications fabricated in standard silicon planar technology at the STMicroelectronics Catania R&D clean room facility. We have improved our previous Geiger Mode Avalanche Photodiodes (GMAP) technology in order to realize a photodetector with relevant features in terms of single-photoelectron resolution, timing and photon detection efficiency. The performances of our devices, investigated in several experimental conditions and here reported make ST-SiPM suitable in many applications like for example PET (Positron Emission Tomography).

Structure and Conductance of the Breakdown Spot During the Early Stages of Progressive Breakdown

It has been shown that under accelerated stress below ap4 V, thin gate oxides are subject to progressive breakdown (BD), i.e., a gradual growth of the BD spot up to a destructive BD. This paper investigates the conduction mechanisms of the BD spot during the early stages of progressive BD through the measurement of the I-V characteristics using carrier separation. It is shown that a model with no free parameter based on the concept of cotunneling provides a good evaluation of the post-BD current. This model implies a physical microstructure, and its plausibility is compared to direct transmission electron microscopy (TEM) observations

Enhanced blue-light sensitivity P on N Silicon Photomultipliers

Silicon Photomultipliers (SiPMs) have known a fast development in recent years, due to their excellent single photon detection capability and very fast timing response. In this paper we present the results of the electro-optical characterization performed on the first STMicroelectronics P on N SiPMs prototypes properly designed for their possible application in Positron Emission Tomography (PET). We will show that the performances of the new devices are extremely promising in terms of high photon detection efficiency and fast timing response in blue wavelength range.

Understanding dark current in pixels of silicon photomultipliers

Silicon photomultipliers are nowadays considered a promising alternative to conventional vacuum tube photomultipliers. The physical mechanisms operating in the device need to be fully explored and modeled to understand the device operational limits and possibilities. In this work we study the dark current behavior of the pixels forming the Si photomultiplier as a function of the applied overvoltage and operation temperature. The data are well modeled by assuming that dark current is caused by current pulses triggered by events of diffusion of single minority carriers (mostly electrons) injected from the boundaries of the active area depletion layer (dominating at temperatures above 0°C) and by thermal emission of carriers from Shockley-Read-Hall defects in the depletion layer (dominating at temperatures below 0°C).