[en] The numerical simulation of a silicon microstrip detector is discussed. Physical models for the bulk radiation damage have been taken into account, based on a generalized Shockley-Read-Hall expression of the recombination rate. The actual shape of depletion layer, depending on the radiation fluence, has been investigated. The build-up of a dual depletion layer, as reported in some literature works, has been described and interpreted

[en] In this work, the application of numerical device simulation to the analysis of high resistivity silicon microstrip detectors is illustrated. The analysis Of DC, AC and transient responses of a single-sided, DC-coupled detector has been carried out, providing results in good agreement with experimental data. In particular, transient-mode simulation has been exploited to investigate the collection of charges generated by ionizing particles. To this purpose, an additional generation term has been incorporated into the transport equations; the motion of impact-generated carriers under the combined action of ohmic and diffusive forces is hence accounted for. Application to radiation tolerance studies is also introduced

[en] In this paper, the application of device simulation techniques to the design of silicon microstrip detectors devised for the CERN-CMS experiment is illustrated. Simulation strategies are summarized, focusing on radiation-related issues. Some practical examples are discussed, related to the optimization of detectors: low-resistivity substrates are analyzed, looking for improvement of long-term radiation hardness; overhanging metal contacts are studied, aiming at preventing occurrence of breakdown and early micro-discharges; thick-substrate detectors are investigated, in view of the exploitation of large-pitch devices in the outer layers of the tracker. Some emphasis is placed on the use of simulation as a physical interpretation aid, which supports detailed understanding of the device behavior

[en] Low-resistivity materials have been proposed for the fabrication of radiation-hard solid-state particle detectors. A complete analysis of low-resistivity detector performance, including the estimate of charge collection efficiency, has been carried out by using a numerical device simulator, and compared with results expected from conventional, high-resistivity devices. By exploiting the features of the CAD environment, characterization of devices over a wide range of fluences and applied biases has been possible, avoiding the actual fabrication of prototypes, as well as lengthy and expensive testing procedures. Encouraging results have been obtained: low-resistivity devices appear to provide some definite advantages in terms of long-term performance optimization

[en] In this paper, numerical analysis techniques are applied to the study of microstrip silicon detectors exploited in the field of high-energy physics. At high luminosity required by future experiments, radiation hardness of such device becomes a critical issue. The adoption of relatively low-resistivity substrates has been suggested as a key to face such a problem: simulations have been carried out to verify this assumption. Comparisons have been made in terms of depletion voltage, as well as of charge-collection efficiency, by exploiting some of the features of a customized simulation environment. Estimated, long-term radiation hardness of low-resistivity detectors favorably compares with high-resistivity ones

[en] In this paper, a TCAD-based analysis of unconventional-geometry microstrip radiation detectors is discussed. In particular, thick-substrate and large-pitch devices, recently suggested for the adoption in outer layers of particle tracking systems have been considered. Correlation among parasitic capacitance and geometrical features is discussed, providing intuitive interpretation for experimentally observed behaviors. Influence of the substrate thickness on depletion voltage is discussed, and dependence of detector performance on the width/pitch ratio is taken into account as well, providing a complete picture of the behavior of thick-substrate devices, in view of their future use in LHC experiments

[en] The changes of the electrical properties induced by hadron irradiation on silicon detectors have been studied by using the device level simulator HFIELDS. The model of the radiation damage assumes the introduction of radiation-induced acceptor and donor 'deep-levels'. The electric field profile and the space charge region extension have been calculated for differently irradiated structures. The simulation has been carried out at different biases in order to study the evolution of the space charge region of irradiated detectors as a function of the applied voltages, below and above the full depletion. The time-dependent current responses and the charge collection properties of the structure illuminated by a red LED light have been calculated. The use of the red light results in a shallow (quasi-surface) generation of e-h pairs in silicon, which has been properly taken into account by the simulation. The results of the simulations have been compared to experimental measurements carried out at CERN on samples irradiated with 24 GeV/c protons. The comparison results in a satisfactory agreement, and supports the physical interpretation of experimental data

[en] To measure the intrinsic spatial resolution of silicon pixel sensor is usually a non-trivial task, particularly for small pixel sizes where the multiple scattering may be the limiting factor. In this work, we present a new measurement technique to obtain the intrinsic spatial resolution of silicon active pixel sensors. The method relies on the capability of the device to record the passage of a charged particle, incoming at a grazing angle, over several tens or hundreds of pixels, acting as a solid state ionization chamber and thus defining a track. The track will then be fitted by a line and the intrinsic spatial resolution will be obtained using two methods: i) extracted by the σ of the fit; ii) defining a telescope-on-chip configuration to find a residual distribution. Comparison with a more traditional measurement (telescope configuration) and a discussion on the limit of this technique, when the pixel size shrinks, will also be presented

[en] Radiation hardness is a critical design constraint for current and future generation silicon detectors, which are foreseen to undergo radiation fluences higher than 1x10¹⁴ cm^-2 1-MeV neutron equivalent. Recently, low-temperature operating conditions have been suggested as an effective means to recover the negative effects of radiation damage on silicon detector collection properties. In order to investigate such an effect, simulations have been carried out using the ISE-TCAD DESSIS device simulator. The simulated results are compared with charge collection spectra obtained with 1064 nm laser pulses on devices irradiated with 23 GeV protons as a function of detector bias voltage. Thousands of simulation results have been cross-checked with the experimental data. The results obtained so far indicate that the 'three-level model' can be successfully extended to predict irradiated detector behavior at least down to a temperature of 190 K

[en] In this paper we discuss an enhanced approach to the analysis of radiation-damaged silicon devices, with reference to numerical modelling implemented in a general-purpose device simulator. In particular, the emission and capture mechanism of deep levels are accounted for by means of Shockley-Read-Hall theory and shallow-level sensitivity to radiation is considered by means of a donor removal model. The effects produced by regions containing very high defect concentrations (referred to as 'clusters') are considered by calculating the direct charge exchange between two deep levels. The resulting analysis technique has been validated and calibrated by means of comparison with experimental measurements carried out on irradiated samples. The model is shown to provide comprehensive and accurate results for several radiation damage phenomena