Showing papers by "Sabina Ronchin published in 2004"

Fabrication of PIN diode detectors on thinned silicon wafers

Abstract: Thin substrates are one of the possible choices to provide radiation hard detectors for future high-energy physics experiments. Among the advantages of thin detectors are the low full depletion voltage, even after high particle fluences, the improvement of the tracking precision and momentum resolution and the reduced material budget. In the framework of the CERN RD50 Collaboration, we have developed p–n diode detectors on membranes obtained by locally thinning the silicon substrate by means of tetra-methyl ammonium hydroxide etching from the wafer backside. Diodes of different shapes and sizes have been fabricated on 57 and 99 μm thick membranes. They have been tested, showing a very low leakage current (

A study for the detection of ionizing particles with phototransistors on thick high-resistivity silicon substrates

Abstract: We report on bipolar NPN phototransistors fabricated at ITC-IRST on thick high-resistivity silicon substrates. The phototransistor emitter is composed of a phosphorus n+ implant, the base is a diffused high-energy boron implant, and the collector is the 600–800 μm thick silicon bulk, contacted on the backplane. We have studied the current amplification for two different doping profiles of the emitter, obtaining values of β ranging from 60 to 3000. For various emitter and base configurations, we measured the static device characteristics and extracted the leakage currents and the base resistance, verifying the fundamental relationship between them and the total base capacitances. The use of such phototransistors to detect ionizing particles is exploited and discussed.

Characterization of BJT-based particle detectors

Abstract: We report on the static and dynamic behavior of BJT-based particle detectors realized on high-resistivity silicon. Several prototypes, featuring different doping profiles and geometries, have been fabricated at ITC-irst (Trento, Italy). These devices have been thoroughly characterized from the electrical viewpoint, and, in order to understand the fundamental parameters of the structure, device simulations have been performed, whose results are in very good agreement with experimental data. Preliminary functional measurements have been carried out by using a 109 Cd source excitation.

High-gain phototransistors on high-resistivity silicon substrate

Abstract: NPN phototransistors have been fabricated on high-purity silicon substrate. The devices have been produced by ITC-IRST in the framework of a National Research Project funded by the Italian Education, University and Research Ministry (MIUR). The phototransistor emitter is composed of a phosphorus n + implant, the base is a diffused high-energy boron implant, and the collector is the 300 μm thick silicon bulk. Several devices have been investigated. Results with 22 keV X-ray from a 109 Cd-radioactive source and visible light irradiation are presented.

Analysis of the radiation hardness and charge collection efficiency of thinned silicon diodes

Abstract: Due to their low depletion voltage, even after high particle fluences, improved tracking precision and momentum resolution and reduced material budget, thin substrates are one of the possible choices to provide radiation hard detectors for future high energy physics experiments In the framework of the CERN RD50 Collaboration, we have developed p-n diode detectors on membranes obtained by locally thinning the silicon substrate by means of TMAH etching from the wafer back-side Diodes of different shapes and sizes have been fabricated on 50-/spl mu/m and 100-/spl mu/m thick membranes and tested, showing a low leakage current (about 300 nA/cm/sup 3/) and, as expected, a very low depletion voltage (in the order of 1 V for the 50-/spl mu/m membrane) Radiation damage tests have been performed with 58-MeV Li ions at the SIRAD Irradiation Facility of the INFN National Laboratory of Legnaro, Italy, up to a fluence of 183 /spl times/ 10/sup 13/ Li/cm/sup 2/ Moreover, charge collection efficiency tests performed at INFN Firenze with a /spl beta/ particle source have been performed on both non-irradiated and irradiated samples Results here reported confirm the advantages of thinned diodes with respect to standard ones in terms of low depletion voltage and charge collection efficiency even after the highest ion fluence

High-gain bipolar phototransistor on high-resistivity silicon substrate: a new device for the detection of ionizing radiation

Abstract: NPN bipolar phototransistors have been designed and fabricated on high-resistivity silicon substrates of different thicknesses, up to 800 /spl mu/m. A technology featuring a double implant for the emitter allowed us to obtain a typical current gain of about 600. The device has been used to detect /spl alpha/ particles from a /sup 239/Pu source, /spl beta/ particles from /sup 90/Sr and X-rays from /sup 241/Am using a simple experimental set-up, by directly connecting the detector to the scope. In the case of electrons, typical pulse heights of 100 mV have been observed, with pulse length of 50/spl mu/s, measured on a load resistor in series to the emitter. The parameters driving the time performance have been measured, obtaining a good agreement with the electrical model of the device. We report on the functional characterization of the device with emphasis on the energy calibration and the electronic noise measurement.

Recent results from the development of silicon detectors with integrated electronics

Abstract: In the past few years we have developed a technological process allowing for the fabrication of radiation detectors with integrated electronics on high-resistivity silicon substrates. We report on some recent results relevant to the process optimisation and to device/circuit characterization.

Characterization and TCAD modelling of termination structures for silicon radiation detectors

Abstract: We have recently proposed a novel junction termination structure for silicon radiation detectors, featuring all-p-type multiguard and scribe-line implants, with metal field-plates completely covering the gap between the implanted rings. The structure is intended for detector long-term stability enhancement even in adverse ambient conditions and for fabrication-process simplification. A thorough static characterization, including stability measurements in varying humidity conditions, has been carried out on a variety of samples fabricated at ITC-irst. Comparisons with diodes featuring an n-type implant along the border—or no edge structure at all—have been performed. The new structures show stable behaviour at relatively high bias (∼200 V ) , also in the presence of wide humidity changes (1–90%). A good qualitative agreement has been obtained between experimental results and simulation predictions, allowing to gain deep insight into the physical behaviour of the device.

Study of neutron pre-irradiated silicon for nuclear detectors

Abstract: The ways of increasing the radiation hardness of silicon were considered It was then experimentally shown that a preliminary irradiation of the bulk silicon introduces sinks for radiation defects that leads to an increased radiation hardness of the silicon Neutron transmutation doping of silicon can be considered as one form of preliminary radiation It was shown that for neutron transmutated silicon the carrier removal rate in NTD after /spl gamma/-irradiation is more than one order of magnitude smaller than in a standard reference specimen, but the carriers removal rate after neutron irradiation is approximately a factor of two less