Heavy Ions In Silicon Research Articles

Radiation Damage by Heavy Ions in Silicon and Silicon Carbide Detectors.

While silicon has been a steadfast semiconductor material for the past 50 years, it is now facing competition from other materials, especially for detector design. In that respect, due to its high resistance to radiation damage, silicon carbide is one of the most promising materials. In this work, we discuss the radiation damage studies of a new, large area, p-n junction silicon carbide device developed by the SiCILIA collaboration. We have studied the general performances of several devices, as a function of fluence, irradiated in different experimental conditions with different beams. A standard p-n junction silicon detector was also irradiated for comparison. The new detectors manifest excellent performance in terms of stability of the main parameters, linearity, defect distribution, charge collection efficiency, energy resolution, leakage current, etc. Experimental results evidence a radiation resistance of SiC devices more than two order of magnitude higher than Si devices. The new construction technology applied to silicon carbide material has made it possible to create very robust devices with excellent performance. These devices will soon be available for all those scientific projects where a high resistance to radiation damage is required.

Impact of proton-induced alteration of carrier lifetime on single-event transient in SiGe heterojunction bipolar transistor**Project supported by the National Natural Science Foundation of China (Grant Nos. 11775167, 61574171, 11575138, and 11835006).

This paper presents an investigation into the impact of proton-induced alteration of carrier lifetime on the single-event transient (SET) caused by heavy ions in silicon–germanium heterojunction bipolar transistor (SiGe HBT). The ion-induced current transients and integrated charge collections under different proton fluences are obtained based on technology computer-aided design (TCAD) simulation. The results indicate that the impact of carrier lifetime alteration is determined by the dominating charge collection mechanism at the ion incident position and only the long-time diffusion process is affected. With a proton fluence of 5×1013 cm−2, almost no change is found in the transient feature, and the charge collection of events happened in the region enclosed by deep trench isolation (DTI), where prompt funneling collection is the dominating mechanism. Meanwhile, for the events happening outside DTI where diffusion dominates the collection process, the peak value and the duration of the ion-induced current transient both decrease with increasing proton fluence, leading to a great decrease in charge collection.

Geant4 physics processes for microdosimetry simulation: Very low energy electromagnetic models for protons and heavy ions in silicon

The Geant4-DNA extension of the Geant4 Monte Carlo simulation toolkit aims at modeling early biological damages induced by ionizing radiation at the DNA scale, and it can now track particles down to very low energies in liquid water. New models, called “MuElec”, have been implemented for microelectronic applications following the same initial theory, to track low energy electrons in silicon. This paper presents the extension of these MuElec models to incident protons and heavy ions in silicon. First, the theory of the model is presented. The resulting cross sections and stopping powers are compared with data from the literature. The model is then implemented in Geant4 and used to simulate proton tracks. Various physical quantities are extracted from the simulation, and compared with data from the literature and with results from simulation using other Geant4 models. It is shown that the generation of low-energy electrons results in more physically meaningful low-energy secondary electron tracks, which significantly modifies the proton and ion track core on the nanometer scale.

Experimental Linear Energy Transfer of Heavy Ions in Silicon for RADEF Cocktail Species

Experimental linear energy transfer values of heavy ions in silicon are presented with comparison to estimations from different semi empirical codes widely used among the community. This paper completes the experimental LET data for the RADEF cocktail ions in silicon.

Linear Energy Transfer of Heavy Ions in Silicon

Researchers performing radiation testing on electronic components often rely on semi-empirical prediction codes for determining the linear energy transfer (LET) (or electronic stopping force) of ions, without paying much attention to their reliability. However, it is seen that estimations calculated with different codes can have over 10% discrepancies, especially in the case of heavy ions with higher LET (e.g., xenon). As a consequence of the modern component fabrication techniques this has become an important issue when studying the radiation durability of electronics. In order to clarify this inconsistency, LET measurements for 131Xe and 82Kr in silicon have been undertaken and obtained results are presented, discussed and compared with earlier predicted data.

Amorphous pockets in Si: Comparison of coupled molecular dynamics and TEM image contrast simulations with experimental results

The size of collision cascades of heavy ions in silicon as calculated by molecular dynamics or other simulation methods is considerably larger than the size of the amorphous pockets observed by transmission electron microscopy (TEM). Using multislice TEM image contrast simulations with atom coordinates from molecular dynamics simulations, we show that the peripheries of the collision cascades should be visible in the TEM if they existed at the time of analysis. We argue that the most likely reason for the discrepancy is thermal annealing. In order to guarantee exactly the same TEM conditions in the simulation and the experiment, we have performed low-dose Ge, Te, and Pb implantations at cryogenic and room temperature, and use them in the comparison.

Electronic stopping powers for heavy ions in silicon

The stopping powers in silicon of heavy ions, with atomic numbers ranging from 4 to 29, have been determined using a time-of-flight elastic recoil detection analysis (TOF ERDA) set-up. In transmission geometry, the energy loss of heavy elastic recoils in the self-supporting silicon foil of known thickness is measured over a continuous range of recoil energies using time-of-flight (TOF) spectrometry. By essentially calibrating the Si detector for each channel over the measured energy region using the TOF spectrometer, an uncertainty of less than 4% is achieved. The stopping powers are parameterized using a sixth order polynomial and compared with the limited experimental data in the literature. In the energy regimes where experimental data exist, the present data exhibit good agreement with most data. Stopping powers predicted by SRIM (the stopping and range of ions in matter) are in reasonable agreement with much of the experimental data, and SRIM-2003 predictions are in somewhat better agreement than SRIM-2000. There are, however, still some discrepancies between SRIM predictions and the experimental data.

Langevin model for axial channeling

A Langevin model simulation of channeling trajectories has been developed. This uses numerical solution of the equation of motion in a continuum potential together with a randomly fluctuating force derived from the diffusion coefficient of the diffusion model of dechanneling. This permits ready comparison with the transverse energy-based approach of the continuum model while being less computationally expensive than a full Monte Carlo simulation. Examples of the application of the model to dechanneling of protons in silicon, and to the charge exchange cooling and heating of heavy ions in silicon are given.

Z1-dependence of low energy heavy ion range parameters

Abstract Range parameter calculations were performed for heavy ions in silicon and aluminium in the low energy range (&<1). The results of the obtained Z1-oscillation of the range parameters are compared with experimental ones and other calculations.

Particle identification with silicon-surface-barrier detector time-of-flight telescopes in reactions with very heavy ions

Si-detector ΔE- E time-of-flight telescopes were used to identify heavy ions with masses 60 ⩽ A ⩽ 208 in the energy range from 300 to 1200 MeV. Calibration procedures for the determination of the mass, charge and energy of the detected particles are described. Experimental data for the energy loss of heavy ions in silicon are presented, and are compared with values from currently used data tables.

Comparison of range-energy calculations of heavy ions in silicon using the inverse square law and thomas-fermi potentials

Abstract The projected range and projected range straggling of heavy ions in silicon are calculated using an inverse square law potential. These results are compared with similar computations using the Thomas-Fermi potential. It is shown that there is reasonable agreement between these two models for ion energies between 20–400 keV.