Damage In Semiconductors Research Articles

Ion-Irradiated Damage in Semiconductors Visualized by Means of Low-kV Scanning Electron Microscopy

Journal Article Ion-Irradiated Damage in Semiconductors Visualized by Means of Low-kV Scanning Electron Microscopy Get access Iwona Jozwik, Iwona Jozwik Institute of Electronic Materials Technology, Warsaw, PolandNational Centre for Nuclear Research, NOMATEN Centre of Excellence, Swierk-Otwock, Poland Search for other works by this author on: Oxford Academic Google Scholar Adam Barcz, Adam Barcz Institute of Electron Technology/Institute of Physics PAS, Warsaw, Poland Search for other works by this author on: Oxford Academic Google Scholar Ewa Dumiszewska, Ewa Dumiszewska Institute of Electronic Materials Technology, Warsaw, Poland Search for other works by this author on: Oxford Academic Google Scholar Elzbieta Dabrowska Elzbieta Dabrowska Institute of Electronic Materials Technology, Warsaw, Poland Search for other works by this author on: Oxford Academic Google Scholar Microscopy and Microanalysis, Volume 25, Issue S2, 1 August 2019, Pages 486–487, https://doi.org/10.1017/S1431927619003167 Published: 01 August 2019

Determination of radiation hardness of silicon diodes

In this paper, we describe an experiment aimed to measure the physical observables, which can be used for the assessment of the radiation hardness of commercially available silicon photo diodes commonly used as nuclear detectors in particle accelerator laboratories. The experiment adopted the methodology developed during the International Atomic Energy Agency (IAEA) Coordinated Research Project (CRP No. F11016) “Utilization of Ion Accelerators for Studying and Modelling Ion Induced Radiation Defects in Semiconductors and Insulators”.This methodology is based on the selective irradiation of micrometer-sized regions with different fluences of MeV ions using an ion microbeam and on the measurement of the charge collection efficiency (CCE) degradation by Ion Beam Induced Charge (IBIC) microscopy performed in full depletion condition, using different probing ions.The IBIC results are analyzed through a theoretical approach based on the Shockley-Read-Hall model for the free carrier recombination in the presence of ion-induced deep traps. This interpretative model allows the evaluation of the material radiation hardness in terms of recombination parameters for both electrons and holes.The device under study in this experiment was a commercial p-i-n photodiode, which was initially characterized by i) standard electronic characterization techniques to determine its doping and ii) the Angle-Resolved IBIC to evaluate its effective entrance window. Nine regions of (100 × 100) µm2 were irradiated with 11.25 MeV He ions up to a maximum fluence of 3·1012 ions/cm2. The CCE degradation was measured by the IBIC technique using 11.25 MeV He and 1.4 MeV He as probing ions.The model presented here proved to be effective for fitting the experimental data. The fitting parameters correspond to the recombination coefficients, which are the key parameters for the characterization of the effects of radiation damage in semiconductors.

Evolution of radiation defects in NPN bipolar junction transistors irradiated by 3 MeV protons

In space, energetic proton irradiation produces both ionization and displacement damage in semiconductors and devices served in spacecraft. In order to separate the ionization and displacement damage in bipolar junction transistor (BJT), the electrical degradation and radiation-induced defects were studied during 3 MeV proton irradiation and the annealing process. The current gain degradation shows a nonlinear relationship with the increasing fluence during irradiation. It can be deduced that the proton irradiation produces the ionization/displacement combined damage in NPN BJTs. Ionization and displacement-induced defects are measured by deep level transient spectroscopy (DLTS) during the isochronal annealing. During the isochronal annealing, the ionization-induced defects annealed at a relatively low temperature (400 K), while the displacement-induced defects recovered at a higher temperature (higher than 500 K). According to the comparison between the DLTS analysis and current gain recovery, the accepter-like defects (V-O and V2(−/0)) act an important role in irradiated NPN BJTs.

Communication—Direct Imaging of Irradiation Damage in Semiconductors by Low-Energy SEM

The performance of the present-day Scanning Electron Microscopy (SEM) extends far beyond delivering electronic images of the surface topography. One of the most noticeable achievements of the technique was recognition of p- and n-type conductive channels on the semiconductor surface. Here, we report on the possibility of visualization of highly resistive layers produced by ion irradiation. The presented high-resolution imaging of damage-induced insulating layers was made possible through application of low energy of the primary beam (1 keV), optimization of the instrument parameters and effective separation of the so-called SE1 vs. SE2 secondary electrons.

Application of spallation neutron sources in support of radiation hardness studies

High-power spallation neutron sources offer a unique opportunity to gather critical measurements on the very early transient displacement damage in semiconductors. This paper discusses the important attributes of spallation neutron facilities used for investigating the transient radiation hardness of semiconductors. By comparing the attributes of some different types of radiation facilities currently used for semiconductor damage characterization, a new and important role for spallation neutron sources is identified. Comparisons are made between the attributes of the spallation neutron source and fast-burst reactors, water-moderated reactors, ion microbeams, and electron accelerators. By incorporating electromagnetic shielding, photocurrent shunts and new experimental techniques, testing at spallation neutron sources has permitted the earliest measurements of transient gain to be lowered from the previous time of 250 μs, achieved at fast-burst reactors, to 8 μs. This is over a factor of 30 improvement in the test capability.

Numerical investigation of ultrashort laser damage in semiconductors

A complete self-consistent model for transport dynamics in semiconductors caused by ultrashort-pulse laser heating is presented based on the relaxation-time approximation of the Boltzmann equation. Carrier–lattice nonequilibrium interactions are simulated to obtain the temporal and spatial evolution of the carrier density and temperature as well as the lattice temperature. It is shown that the calculated damage threshold based on the carrier density criterion agrees fairly well with the experimental data for both Si and Ge semiconductors, especially for sub-picosecond pulses. It is also found that one-photon absorption and Auger recombination are the two critical factors that influence the electron–hole carrier generation.

Comparative Studies Using EXAFS and PAC of Lattice Damage in Semiconductors

We have used the perturbed angular correlation (PAC) method and extended X-ray absorption fine structure spectroscopy (EXAFS), along with microscopic methods to investigate the implantation induced disorder and characterize the ion-induced amorphisation of elemental and compound semiconductors.

Genesis of nanoscale defects and damage in GaAs subjected to multipulse quasi-static photostrains in micrometer-sized regions of semiconductor

Atomic-force microscopy and analysis of both photothermal (quasi-static) strains of surfaces and the kinetics of intensity of specularly reflected light were used to study special features of defect production in GaAs in relation to the number N of focused laser pulses incident on the surface. Irradiation of the semiconduc- tor was accompanied by its electronic excitation, local heating, and deformation of surface layers. It is shown for the first time that the genesis of surface defects and damage in semiconductors (within the laser spot with a micrometer diameter) has a multistage character in the vicinity of the plasticity threshold. The defect-induced and plastic nanometer-scale surface displacements Δ U z increase with increasing N only if the shearing surface strains ϕ exceed the previously determined values 10 -5 < ϕ 0 < 10 -4 for deformation-related elasticity (quasi- elasticity) limits in GaAs. The origination of nanoscale defects and their self-organization at the early stages of photostrains in the semiconductor is discussed. The possible relation between the defects observed and the subsequent catastrophic damage to micrometer-sized regions of GaAs at large values of N is considered. © 2004 MAIK "Nauka/Interperiodica".

Determination of damage profiles in semiconductors using differential reflectance

We review differential reflectance (DR) spectroscopy, an optical technique that can be used to detect damage in semiconductors in a broad range of defect densities. In this study, we focus on the determination of the depth distribution of damage in ion-implanted semiconductors using DR. We give details about the method and discuss experimental results involving ion-implanted GaAs and Si under various conditions. We compare the experimentally determined damage profiles with calculations and show that there is very good agreement between the experiments and the theory.

Effect of laser-induced antidiffusion on excited conduction electron dynamics in bulk semiconductors

By including the effect of local fluctuations in the electron kinetic energies, the kinetic Fokker-Planck-type equation for excited conduction electrons in bulk semiconductors (such as GaAs, Si, etc.) is systematically derived in the presence of a pulsed laser beyond the classical limit. A new contribution from an antidiffusion process is found as a correction to the spontaneous-phonon emission from drifting electrons in addition to contributions from joule heating and a field-dependent diffusion of electrons. The stimulated interband optical transitions of electrons from single-photon absorption are included as one of the source terms of the equation. Some possible types of damage in semiconductors including optical, electrical, and structural damage are explored. The calculated results demonstrate the existence of a kinklike feature in the electron distribution function around the edge of the conduction band due to antidiffusion. The energy spectra of the electron distribution function are studied at different times and used to analyze the transient behavior of both the conduction electron density and the hot-electron temperature.

Low-energy ion damage in semiconductors: A progress report

There has been steady progress in understanding the propagation of low-energy, ion-induced damage into semiconductor substrates. The availability of specifically designed heterostructure substrates allows us to trace the profile of damage into the material. A number of experiments, together with theoretical simulations, have confirmed the important role played by fortuitous channeling of ions, deep into the material (e.g., &amp;gt;1000 Å deep for incident ions energies ∼300 eV). Recent experiments have also shown the importance of rapid diffusion of ion-created defects. Using a model that includes the effects of both channeling and defect diffusion, channeling and diffusion in ion damage (CHANDID), we have deduced a room-temperature diffusion constant of D∼1×10−15 cm2/s. This is an extremely high value for diffusion at room temperature, and is more characteristic of diffusion taking place at temperatures of a few hundred to a few thousand degrees centigrade. One cause of this high value of D may be attributed to radiation enhanced diffusion: the creation of excess electrons and holes during the etch process whose subsequent nonradiative recombination transfers momentum to the defects. Preliminary experiments, which monitor the effects of above band-gap illumination during ion bombardment, validate this picture. Such understanding, of intrinsic importance, can be used to design material and device structures in which the effects of ion damage may be mitigated.

Novel effects of weak magnetic fields on post-implantation damage in semiconductors and superconducting ceramics

Novel experimentally verifiable and theoretically explained effects of weak static magnetic fields (WSMFs) acting during ion implantation of semiconductors and superconducting ceramics (SCC) at 300 K, moderate ion energies (e.g. 200–400 keV) and low dosage (e.g. 10 11–10 13 m −2) on the post-implantation radiation damage (PIRD) and material parameters are discussed. The WSMF of strength of H ≈ 1 kOe reduces, as previously reported, the PIRD in Hg 08Cd 02Te and InSb by factors of 2 and 1.54, respectively, and can increase the PIRD and change material parameters in SCCs. The WSMF effects on the radiation damage is a generic consequence of the kinetic electron-related theory of atomic rate processes in solids which shows that local electron transitions (LETs) in the nanometer vicinity of hopping atoms (defects) influence exponentially defect formation and migration rates. The magnetic field changing the LET number affects exponentially the rates of formation, migration and agglomeration of point defects and thus change the radiation damage.

Computer controlled specimen stage goniometer for a nuclear microprobe

A computer controlled virtual instrument for a nuclear microprobe specimen stage goniometer is described. This virtual instrument includes many powerful features not previously available on other computer controlled stages. A X-windows interface under the linux operating system provides a virtual instrument control panel on any X-terminal connected to the global net. This allows mouse driven ‘point and click’ control over four stage motions. In addition, two input channels allow continuous measurement of beam current and detector count rate. Each axis is controlled by a stepper motor which can be configured to step in any unit. The virtual instrument may be reconfigured from an initialisation file to adapt to changes in the hardware configuration. Motion of each axis can also be controlled by a flexible command language that allows for four dimensional scanning or any other complicated axis movements in response to elapsed time, accumulated dose or integrated detector counts. An integrated video capture system provides an inset in the virtual instrument control panel for viewing of the specimen in real time. Some applications of this virtual instrument include the identification of the orientation and structure of crystals, the study of radiation induced damage in semiconductors and the direct writing of microstructures in optical materials.

Molecular dynamics simulations of implantation damage and recovery in semiconductors

Numerous experiments on damage in semiconductors due to ion bombardment have shown quite varied material-dependent behaviour. In particular after the recovery phase, the residual damage can vary from almost crystalline to amorphous for given ion bombardment conditions [1]. We have studied both the initial cascade damage and the subsequent recovery using approximate and full molecular dynamics techniques for Si, GaAs and AlAs. These semiconductors are modelled using the Si Tersoff potential which has been modified for GaAs and AlAs. In this presentation, the results of these simulations will be given. These clearly show that AlAs sustains less damage than GaAs, in agreement with experiment.

Molecular dynamics simulations of implantation damage and recovery in semiconductors

Numerous experiments on damage in semiconductors due to ion bombardment have shown quite varied material-dependent behaviour. In particular after the recovery phase, the residual damage can vary from almost crystalline to amorphous for given ion bombardment conditions [1]. We have studied both the initial cascade damage and the subsequent recovery using approximate and full molecular dynamics techniques for Si, GaAs and AlAs. These semiconductors are modelled using the Si Tersoff potential which has been modified for GaAs and AlAs. In this presentation, the results of these simulations will be given. These clearly show that AlAs sustains less damage than GaAs, in agreement with experiment.

Computer simulation of atomic displacements in Si, GaAs, and AlAs

Low energy displacement events produce simple point defects such as Frenkel pairs. Computer simulations of these events are useful as they provide information concerning the nature of damage in semiconductors, and can generate input parameters required for a theoretical study of cascades. Using molecular dynamics simulations we have investigated low energy displacement in Si, GaAs and AlAs for ejections below 32 eV. These materials are modelled using the Si Tersoff potential, which has been modified for the compound semiconductors. For each atomic species we have determined the displacement threshold energy, and its angular dependence together with an estimate of recombination distances. Several ejection processes have been identified. Their directional and energy dependencies will be discussed. The results for Si, GaAs and AlAs are compared and physical reasons are given for the similarities and differences.

Radiation effects research in the 60's

This talk provides a review of some of the significant issues and advances in nuclear radiation effects that took place in the 1960's. The subjects include neutron induced displacement damage in semiconductors and ionization effects in semiconductor and dielectric materials and piece-parts. The relationship between the basic mechanisms and the radiation response of components in the areas of TREE, SGEMP, and thermomechanical effects will be described to show how the necessity for understanding and modeling was driven by the requirements for radiation hardened electronic systems. The accomplishments will be described within the context of a changing atmosphere of; international politics; the demise of atmospheric testing and the birth and evolution of the underground nuclear effects test; the evolution of above ground laboratory test facilities and; the eccentricities and passions of some of the people in the business.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Atomic displacement and total ionizing dose damage in semiconductors

Atomic displacement and total ionizing dose damage in semiconductors

Reduction of post-implantation damage in semiconductors by weak magnetic fields

The experimental evidence of a reduction in the post-implantation damage by a factor of 2 and 1.5 in, respectively, Hg0.8Cd0.2Te and InSb caused by magnetic fields of H=0.7 kOe and 2 kOe at T=300 K is reported. This effect follows from the kinetic theory of atomic rate processes in solids linking them with the local electron transport in the submicrometre vicinity of the atoms, overcoming energy barriers. The magnetic field, which decreases the local electron transport, reduces exponentially rates of formation, migration and agglomeration of point defects and this decreases the post-implantation damage.

A deep-level transient spectroscopy variation for the determination of displacement threshold energies in GaAs

The deep-level transient spectroscopy (DLTS) method is optimized for the observation of radiation damage in semiconductors. A new isothermal variation of the technique is applied to the study of displacement defects in GaAs in order to determine threshold energies and displacement cross sections. A pronounced anisotropy is found for the threshold energy. A linearly increasing displacement probability function is shown to properly model the displacement cross section in &amp;lt;100≳ direction, as compared with the &amp;lt;111≳ direction which requires only a simple step function. Anisotropy leads to a tailing off in the displacement cross section at energies below an ‘‘effective’’ threshold of about 15.5 eV in the &amp;lt;100≳ direction, indicating that the &amp;lt;111≳ direction is more sensitive to displacement damage than the &amp;lt;100≳ direction. Differences in the damage between these two directions are as large as a factor of 2.