Number Of Radiation-induced Defects Research Articles

Influence of Radiation Defects Induced by Low-Energy Protons at a Temperature of 83 K on the Characteristics of Silicon Photoelectric Structures

Irradiation by low-energy products leads to a variation in the electrical, optical, and other properties of the surface layer of semiconductor structures, which gives additional possibilities to modify semiconductor devices. This work is devoted to investigating the influence of radiation defects induced by low-energy protons at a sample temperature of 83 K on the properties of double-sided silicon photoelectric structures with a diffusion n+–p junction. Samples of the n+–p–p+ type are irradiated by a proton flux with a dose of 1015 cm–2 and energy of 40 or 180 keV. To explain the observed regularities of varying the parameters of the current–voltage characteristics and transmission coefficients, the distribution of the average number of interstitial silicon, vacancies, divacancies, and disordered regions formed under these conditions per length unit of the projected path by one proton in the diffusion layer in the space-charge region of the n+–p junction is calculated. It is shown that protons with an initial energy of 40 keV preferentially vary the physical properties of the layer with a high concentration of donors, while protons with an initial energy of 180 keV vary the properties of the space-charge region in the layer containing acceptors. The number of radiation-induced defects at the maximum of the spatial distribution in the n-type region is much smaller than in the p-type region.

Simulation of the Formation of a Cascade of Displacements and Transient Ionization Processes in Silicon Semiconductor Structures under Neutron Exposure

The formation of a disordered defect region in bulk silicon is simulated using the molecular-dynamics method for various energies of a primary recoil atom. Variations in the volume and number of radiation-induced defects in a cluster during its formation are calculated. The generation rates of nonequilibrium carriers and amplitude-temporal dependences of pulses of ionization currents in test Schottky diodes with hyperhigh frequencies are found theoretically.

Ion-Track Modification of a Silicon-Dioxide Film Implanted with Zinc Ions and Annealed in Oxygen

The formation of a zinc-oxide phase in a SiO2 film deposited onto n-type Si substrates grown in the (100) orientation using the Czochralski technique, which is a result of implanting 64Zn+ ions at room temperature, an energy of 50 keV, and a dose of 5 × 1016 cm–2, and subsequent heat treatment in an oxygen atmosphere at elevated temperatures, is studied. The surface topology is investigated using methods of scanning electron and atomic force microscopy. The optical properties are studied using the method of photoluminescence spectroscopy at 10 K and by measuring the light reflection spectra. After Zn implantation, a ZnO phase is detected in the subsurface layer of the SiO2 film. After low-temperature annealing in the range of 400–600°С, Zn-containing precipitates with a cross-sectional size of particles of 20–50 nm are found in the sample and on its surface. After annealing at 700–800°C, Zn-containing precipitates of the Zn·ZnO complex are formed in the subsurface layer, and a phase of the ZnO · Zn2SiO4 complex is found after annealing at temperatures of 900–1000°C. The samples obtained at the annealing temperature optimal for the formation of the ZnO phase (about 700°C) are irradiated with 132Xe26+ ions with an energy of 167 MeV. The ZnO phase is found to disappear after irradiation at a fluence of 2 × 1013 cm–2 and a large number of radiation-induced defects giving a characteristic photoluminescence band are formed. With an increase in the Xe fluence to 5 × 1014 cm–2, the intensity of this luminescence band increases.

Моделирование образования каскада смещений и переходных ионизационных процессов в кремниевых полупроводниковых структурах при нейтронном воздействии

AbstractThe formation of a disordered defect region in bulk silicon is simulated using the molecular-dynamics method for various energies of a primary recoil atom. Variations in the volume and number of radiation-induced defects in a cluster during its formation are calculated. The generation rates of nonequilibrium carriers and amplitude-temporal dependences of pulses of ionization currents in test Schottky diodes with hyperhigh frequencies are found theoretically.

Effect of Radiation-Induced Defects Produced by Low-Energy Protons in a Heavily Doped Layer on the Characteristics of n+‒p‒p+ Si Structures

The irradiation of semiconductor structures with low-energy protons is used to control changes in their properties at a depth ranging from 0.1 to 1000 μm. Devices manufactured from such structures have high sensitivities to changes in the state of the surface region. The paper is dedicated to studying the effect of radiation-induced defects produced by low-energy protons in a heavily doped diffusion region on the properties of Si structures with an n+‒p junction. The structures are irradiated with a flux of protons with an energy of 40 keV and a dose of 1015 cm−2 at a sample temperature of 83 and 300 K. The distributions of the average number of interstitial Si, vacancies, and divacancies produced by one proton under these conditions per length unit of the projective range in the diffusion layer of an n+‒p junction are calculated. It is shown that the number of radiation-induced defects in the distribution maximum at a depth of 0.39 μm in a layer with n-type conductivity at a sample irradiation temperature of 83 K is significantly less than that at 300 K. This conclusion is confirmed by the results of studies of electrophysical and optical properties of irradiated n+‒p‒p+ structures.

Radiation damage in the diamond based beam condition monitors of the CMS experiment at the Large Hadron Collider (LHC) at CERN

The Beam Condition Monitor (BCM) of the CMS detector at the LHC is a protection device similar to the LHC Beam Loss Monitor system. While the electronics used is the same, poly-crystalline Chemical Vapor Deposition (pCVD) diamonds are used instead of ionization chambers as the BCM sensor material. The main purpose of the system is the protection of the silicon Pixel and Strip tracking detectors by inducing a beam dump, if the beam losses are too high in the CMS detector. By comparing the detector current with the instantaneous luminosity, the BCM detector efficiency can be monitored. The number of radiation-induced defects in the diamond, reduces the charge collection distance, and hence lowers the signal. The number of these induced defects can be simulated using the FLUKA Monte Carlo simulation. The cross-section for creating defects increases with decreasing energies of the impinging particles. This explains, why diamond sensors mounted close to heavy calorimeters experience more radiation damage, because of the high number of low energy neutrons in these regions. The signal decrease was stronger than expected from the number of simulated defects. Here polarization from trapped charge carriers in the defects is a likely candidate for explaining the difference, as suggested by Transient Current Technique (TCT) measurements. A single-crystalline (sCVD) diamond sensor shows a faster relative signal decrease than a pCVD sensor mounted at the same location. This is expected, since the relative increase in the number of defects is larger in sCVD than in pCVD sensors.

Radiation-hardened microelectronics for space applications

Radiation-hardened technology for space applications will be evaluated in light of its survivability in the total-dose, cosmic-ray, and solar flare environments normally encountered in space. Several examples of technology development programs will be summarized, including Sandia programs over the last two decades. Techniques for optimizing the radiation hardnes of CMOS technologies for space will be discussed. For total-dose hardness, these techniques provide information about the number of radiation-induced defects and their microscopic nature, and are used to identify manufacturing processes that play an important role in the fabrication of radiation-hardened integrated circuits (ICs). For examples, the roles of high-temperature anneals, hydrogen and interfacial strain in the buildup of radiation-induced defects have received a great deal of attention, and many CMOS process flows have been designed to minimize hydrogen incorporation and reduce interfacial stress. Techniques for ensuring the tolerance of ICs to single-event phenomena (SEP) will be addressed, including the manufacture and control of high-resistivity polysilicon feedback resistors. Finally, some future trends in hardness assurance and testing that support more cost-effective qualification of ICs used in space will be covered. For total-dose, trends include wafer-level testing and X-ray irradiations; while for EP, trends include Cf-252 and laser testing

Surface Modification and Radiation-Induced Segregation

ABSTRACTLarge changes in the distributions of alloying components have been observed in a wide variety of alloys during ion bombardment. This metastable, radiation-induced segregation (RIS) results from the preferential transport of alloying components by defect fluxes. Since the number of radiationinduced defects can exceed the number of implanted ions by several orders of magnitude, RIS can be highly efficient in modifying near-surface alloy compositions. In this paper, the general features of RIS are described. Aspects which are pertinent to the modification of materials by ion beams are emphasized. Examples are given of surface modifications which utilize RIS effects.