Carrier transport in a SiC detector subjected to extreme radiation doses
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ICS OF SEMICONDUCTOR DEVICES
Carrier Transport in a SiC Detector Subjected to Extreme Radiation Doses A. M. Ivanov^, A. A. Lebedev, and N. B. Strokan Ioffe Physicotechnical Institute, Russian Academy of Sciences, St. Petersburg, 194021 Russia ^e-mail: [email protected] Submitted December, 12, 2005; accepted for publication, December 30, 2005
Abstract—The efficiency of charge transfer in SiC detectors irradiated with 8 MeV protons at a dose of 1014 cm–2 has been studied. The number of defects originally created in this irradiation mode is equivalent to that of disruptions produced in the lattice of SiC detectors used in experiments on the modernized SLHC collider (CERN). Methods of nuclear spectrometry were employed, with the detectors tested with 5.4 MeV alpha particles. Taking into account the deep compensation of SiC in the course of irradiation, the use of structures in the unconventional forward-biased mode is suggested. In this mode, the electric field strength is distributed across the detector thickness more uniformly. An illustrative model of carrier transport is suggested for processing of experimental data. PACS numbers: 07.77.Ka, 87.66.Pm DOI: 10.1134/S1063782606070232
1. INTRODUCTION In recent years, particular attention has been given to the radiation hardness of semiconductor nuclear radiation detectors operating at doses of relativistic particles of about 1016 cm–2. These values are two orders of magnitude higher than the previously tested doses, the choice of which was governed by the common practice of detector application. The interest in the working capacity of detectors subjected to irradiation with doses of 1016 cm–2 is due to their possible application in fundamentally important experiments of high-energy physics. These include programs carried out at CERN (European Centre for Nuclear and Particle Physics) on the large hadron collider (LHC) and its modification, SLHC. This report describes a procedure for determining the carrier transport parameters in a detector irradiated with the dose specified above. The experiment was carried out with modern SiC detectors irradiated with 8 MeV protons at a dose of 1014 cm–2. This dose is equivalent, as regards the number of atoms knocked out from the SiC lattice, to a dose of 1016 cm–2 of relativistic protons. At such doses, the concentration of radiation centers is comparable with the initial concentration of impurities. The irradiation led to a dramatic increase in the resistivity of the material, and, therefore, further consideration is concentrated on the case of a profound compensation of the semiconductor. 2. FORMULATION OF THE PROBLEM Commonly, the performance of a detector is defined by the charge collection efficiency (CCE). In determin-
ing this parameter, a diode detector is reverse-biased (i.e., operates in the conventional working mode) and the signal is measured as a function of bias. Naturaldecay alpha particles are, as a rule, used as a testing radiation. At first glance, deep compensation of a semiconductor facilitates the d
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