1,721,028 research outputs found
A SPICE model for Si microstrip detectors and read-out electronics
No full textWe have developed a SPICE model of silicon microstrip detector and its read-out electronics. The SPICE model of an AC-coupled single-sided polysilicon-biased silicon microstrip detector has been implemented by using a RC network containing up to 19 strips. The main parameters of this model have been determined by direct comparison with DC and AC measurements. The simulated interstrip and coupling impedance and phase angle are in good agreement with experimental results, up to a frequency of 1 MHz. We have used the PreShape 32 as our read-out chip for both the simulation and the measurements. It consists of a charge sensitive preamplifier followed by a shaper and a buffer. A current pulse, simulating the charge signal of an ionizing particle, has been applied to one end of a single strip. Its propagation along the strips and the read-out electronics has been experimentally studied and compared to the SPICE results in order to assess the quality of the model. The SPICE parameters have been adjusted to fit the experimental results obtained for the configuration where every strip is connected to the read-out electronics and kept the same for the different read-out configurations we have considered. By adding 2 further capacitances simulating the parasitic contributions between the read-out channels of the PS32 chip, a satisfactory matching between the experimental data and the simulated curves has been reached on both rising and trailing edges of the signal. Such agreement deteriorates only for strips far from the strip where the signal has been applied
Defect characterization in silicon particle detectors irradiated with Li ions
No full textHigh Energy Physics experiments at future very high luminosity colliders will require ultra radiation-hard silicon detectors that can withstand fast hadron fluences up to 10^(16) cm^(-2). In order to test the detectors radiation hardness in this fluence range, long irradiation times are required at the currently available proton irradiation facilities. Energetic (58 MeV) Lithium (Li) ions, with experimental hardness factor about two orders of magnitude higher than 24 GeV protons for 280-300 μm thick detectors, could represent a promising alternative radiation source. In this study, the degradation mechanisms in single pad p+-n Standard Float Zone (STFZ) and Diffusion Oxygenated Float Zone (DOFZ) Si detectors irradiated with Li ions up to the fluence of 2.9×10^(12) Li/cm^(2) have been investigated by means of Photo Induced Current Transient Spectroscopy and Thermally Stimulated Currents. Results are compared with the radiation damage induced by 24 GeV proton, 1 MeV neutron and 60Co γ-ray irradiation. The critical Li ion fluence for cluster formation is found to be in the range 4.1-21×10^(11) Li/cm^(2) and its correlation to the corresponding value for hadrons is discussed
SPICE evaluation of the S/N ratio for Si microstrip detectors
No full textSPICE simulations of AC-coupled single-sided Si microstrip detectors connected to the Pre-Shape 32 read-out chip have been performed in order to determine the geometrical characteristics (i.e. the strip pitch p and width w) which maximize the signal-to-noise ratio at room temperature. All the resistive and capacitive elements of the detector have been determined as a function of the w/p ratio, by considering experimental and simulated data available in the literature. The SPICE model takes into account all the main noise sources in the detector and read-out electronics. The minimum ionizing particle current signal shape characteristics have been introduced in the simulations. Two read-out configurations (every strip or every second strip) have been investigated for 6.4 cm and 12.8 cm long detectors. Finally, general guidelines in the detector design have been proposed starting from the simulation results
MOSFET parameter degradation after Fowler–Nordheim injection stress
No full textWe have investigated the degradation of tunnel oxides due to Fowler-Nordheim electron injection from polysilicon gate. Tested devices are n-MOSFET normally used for Flash EPROM applications with four different technologies for the tunnel oxide layer. Stresses have been performed at different source and drain bias conditions for a total injected charge up to 1 C/cm(2). The oxide characteristics and degradation have been determined comparing the MOSFET threshold voltage and transconductance peak for as received devices and after each stress step
Breakdown of coupling dielectrics for Si microstrip detectors
No full textDouble-layer coupling dielectrics for AC-coupled Si microstrip detectors have been electrically characterized in order to determine their performance in a radiation-harsh environment, with a focus on the dielectric breakdown. Two different dielectric technologies have been investigated: SIO2/TEOS and SiO2/Si3N4. Dielectrics have been tested by using a negative gate voltage ramp of 0.2 MV/(cm.s). The metal/insulator/Si I-V characteristics show different behaviours depending on the technology. The extrapolated values of the breakdown field for unirradiated devices are significantly higher for SiO2/Si3N4 dielectrics, but the data dispersion is lower for SiO2/TEOS devices. No significant variation of the breakdown field has been measured after a 10 Mrad (Si) gamma irradiation for SiO2/Si3N4 dielectrics. Finally, the SiO2/Si3N4 DC conduction is enhanced if a positive gate voltage ramp is applied with respect to the negative one, due to the asymmetric conduction of the double-layer dielectric
Degradation of electron irradiated MOS capacitors
No full textWe have investigated the degradation of MOS structure due to high energy electron irradiation as a function of radiation dose and gate bias applied during the irradiation. Devices have been characterized by current-voltage measurements, in order to study charge accumulation also at the gate interface. Three types of oxide charge have been observed: the unstable positive charge, due to trapped holes induced by the electron irradiation; the negative charge in the oxide bulk, deriving from capture of electrons injected during electrical measurements in radiation generated traps; and border traps, at both oxide interfaces
Charge collection efficiency of standard and oxygenated silicon microstrip detectors
No full textTwo silicon microstrip detectors, one fabricated from a standard and the second from a highly oxygenated substrate, were non-uniformly irradiated by 24GeV protons to fluences ranging between 2.3 and 6.3×10^14cm^-2. Charge collection efficiency measurements, performed by pulsing the detectors with a 1060μm wavelength laser, show that the beneficial effect of the oxygenation remains, although reduced with respect to that observed by C-V measurements on diodes fabricated with the detectors
Neutron irradiation effects on standard and oxygenated silicon diodes
No full textSilicon diodes processed on standard and oxygenated silicon substrates by two different manufacturers have been irradiated by neutrons in a nuclear reactor and by the 9Be(d,n)10B nuclear reaction. The leakage current density (JD) increase is linear with the neutron fluence. JD and its annealing curve at 80°C do not present any sizeable dependence on substrate oxygenation and/or manufacturing process. On the contrary, standard devices from one manufacturer present the lowest acceptor introduction rate (β) for the effective substrate doping concentration (Neff), showing that the β dependence on the particular process can be important, overtaking the small substrate oxygenation effect. Finally, the average saturation value of the Neff reverse annealing is slightly lower for the oxygenated samples, pointing out a positive effect of the substrate oxygenation even for devices irradiated by neutrons
HSPICE simulations of Si microstrip detectors
No full textWe report HSPICE simulation results of the signal propagation due to a minimum ionizing particle along the strips of single-sided microstrip detectors connected to the PreShape 32 read-out electronics. The capacitive detector parameter values have been determined as a function of the width/pitch ratio by using measured and calculated data which are available in literature. The strip load capacitance, i.e. the capacitance at the read-out electronics input due to the detector has been calculated by using HSPICE simulations. Different read-out configurations have been investigated. (C) 1998 Elsevier Science B.V. All rights reserved
Low- and High-energy proton irradiations of standard and oxygenated silicon diodes
No full textOxygenated and standard (not oxygenated) silicon diodes processed by two different manufacturers (ST Microelectronics and Micron Semiconductor) have been irradiated by low (27 MeV) and high- (24 GeV) energy protons. The leakage current density increase rate (α) and its annealing do not show any significant dependence on oxygenation and are the same for both manufacturers. Oxygenation improves the radiation hardness by decreasing the acceptor introduction rate (β) and mitigating the depletion voltage (Vdep) increase. Nevertheless, standard ST diodes present β values lower than Micron standard devices and close to oxygenated devices, whose βs are similar for both manufacturers. The amplitude of the Vdep reverse annealing is reduced by oxygenation, which in addition delays the electrically active defect increase, at least for high-energy protons. Oxygenation is consequently the best approach for silicon substrate radiation hardenin
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