This paper provides a historical review of the literature on the effects of radiation-induced displacement damage in semiconductor materials and devices. Emphasis is placed on effects in technologically important bulk silicon and silicon devices. The primary goals are to provide a guide to displacement damage literature, to offer critical comments regarding that literature in an attempt to identify key findings, to describe how the understanding of displacement damage mechanisms and effects has evolved, and to note current trends. Selected tutorial elements are included as an aid to presenting the review information more clearly and to provide a frame of reference for the terminology used. The primary approach employed is to present information qualitatively while leaving quantitative details to the cited references. A bibliography of key displacement-damage information sources is also provided.

Review of displacement damage effects in silicon devices

The process of impurity‐induced layer disordering (IILD) or layer intermixing, in AlxGa1−xAs‐GaAs quantum well heterostructures (QWHs) and superlattices (SLs), and in related III‐V quantum well heterostructures, has developed extensively and is reviewed. A large variety of experimental data on IILD are discussed and provide newer information and further perspective on crystal self‐diffusion, impurity diffusion, and also the important defect mechanisms that control diffusion in AlxGa1−xAs‐GaAs, and in related III‐V semiconductors. Based on the behavior of Column III vacancies and Column III interstitials, models for the crystal self‐diffusion and impurity diffusion that describe IILD are reviewed and discussed. Because impurity‐induced layer disordering has proved to be an important method for III‐V quantum well heterostructure device fabrication, we also review the application of IILD to several different laser diode structures, as well as to passive waveguides. We mention that it may be possible to reali...

Atom diffusion and impurity‐induced layer disordering in quantum well III‐V semiconductor heterostructures

The energy liberated during an electronic transition may take the form of photons (luminescence), secondary electronic excitations (Auger), or phonons. In the case of phonon production, the vibrational excitation is localized at the recombination center (defect) before it dissipates to raise the temperature of the host lattice. A defect in an excited vibrational state may undergo simple solid state reactions such as diffusion, dissociation and annihilation which would not proceed under the Boltzmann distribution of energies determined by the temperature of the quiescent host lattice. The phenomenology of electronic enhancement is reviewed with emphasis on the roles of defect charge state, recombination and electric fields. The application of unimolecular reaction rate theory to the characterization of recombination enhanced reaction kinetics is discussed conceptually. Implications concerning the structural and chemical nature of host materials, recombination centers and reactant products is outlined. The role of recombination enhanced phenomena in device degradation is discussed and some useful applications of REDR in the selective programming of logic arrays and high definition electron beam data storage are presented.

Recombination enhanced defect reactions

The basic mechanisms of space radiation effects on microelectronics are reviewed. Topics discussed include the effects of displacement damage and ionizing radiation on devices and circuits, single-event phenomena, dose enhancement, radiation effects on optoelectronic devices and passive components, hardening approaches, and simulation of the space radiation environment. A summary of damage mechanisms that can cause temporary or permanent failure of devices and circuits operating in space is presented. >

Radiation effects on microelectronics in space

Double heterostructure GaAs–AlxGa1−xAs junction lasers which have very low thresholds and which have been operated continuously at and above room temperature have been fabricated by liquid phase epitaxial growth The threshold current density of these lasers decreases approximately linearly with the thickness of the active region from 3 to at least 05 μm This is interpreted as the result of near perfect carrier and optical confinement as the result of large steps in the energy gap and index of refraction at the heterojunctions in these diodes The gain in these lasers is very high and its dependence upon current density is superlinear Loss is very low and almost that expected from free carriers Complete polarization of the lasing mode was observed This latter is interpreted to be the result of an increased reflection coefficient for the T E mode

GaAs–AlxGa1−xAs Double Heterostructure Injection Lasers

Measurements of minority carrier lifetime damage constant and divacancy growth following neutron irradiation at 76°K have been used to characterize further the annealing of neutron damage in silicon below 300°K. It has been shown that electron injection into p-type silicon at 76°K causes recovery of the neutron induced defect clusters with the simultaneous appearance of divacancies. Comparison of isochronal annealing curves of damage constant taken with and without prior injection at 76°K illustrates the nature of cluster annealing below 300°K. The thermal annealing results are shown to agree with previous annealing measurements of the carrier removal rate.

Thermal and Injection Annealing of Neutron-Irradiated p-Type Silicon between 76°K and 300°K

The application of fiber optic links in both commercial and military space systems, as well as other hostile environments, will mean that these links must be able to withstand exposure to radiation of various types. In this paper, we summarize our work on the effects of radiation on typical emitters and detectors employed in fiber optic links.

The Effects Of Radiation On Optoelectronic Devices

We report here on a study of permanent damage effects in photodiodes due to total dose exposures of 108 rad (Si) ionizing-radiation from a Co60 source. Specifically, we compare the degradation of optical quantum efficiency and increases in photodiode leakage current in Si PIN structures with specially designed and fabricated, double heterostructure AlGaAs/GaAs photodiodes. Results indicate some degradation in quantum efficiency (20-30%) for both types of devices. Leakage currents were found to increase signficantly after 108 rad in the Si PIN structures but only increase slightly in the AlGaAs/GaAs structures.

Permanent Damage Effects in Si and AlGaAs/GaAs Photodiodes

Deep level transient spectroscopy (DLTS) measurements have been performed on a variety of AlxGa1-xAs p-n junctions prior to and following a series of fast neutron irradiations at room temperature and subsequent isochronal anneals. In contrast with electron and proton irradiated GaAs, neutron irradiation produces a single, broad featureless DLTS band which is a majority carrier trap in both n and p type material. The characteristics of this neutron-induced trap are relatively independent of growth method, dopant type and concentration. In GaAs, the thermal emission energies of the trap are 0.58 to 0.68 eV depending on the particular junction. These energies increase with Al content to 0.94 eV at 20% Al. The trap introduction rate, which also increases with Al content, is 0.7 cm-1 in GaAs. Isochronal annealing to temperatures as high as 400‡C results in a smaller FWHM of the DLTS band, a shift in the peak to higher temperatures, and a modest decrease in magnitude. Above 400‡C the magnitude decreases rapidly, suggesting a similarity with the antisite defect, AsGa, which has been observed to anneal in this range.

Neutron-induced trapping levels in aluminum gallium arsenide

The effects of gamma radiation on optical isolators have been investigated. This study has included the simultaneous irradiation and measurement of the individual emitters and detectors making up the isolators. In this manner, the net effect of irradiation on the isolators could be attributed to the degradation of either the emitter or detector, or both. As expected, isolators containing photodiodes are more radiation resistant than those containing phototransistors. In the photodiode isolator the LED is responsible for essentially all the gamma-induced isolator degradation. The performance of phototransistor isolators depends strongly on the phototransistor bias, VCE, and the LED input current, ILED. At high ILED and low VCE where gamma-induced surface effects in the phototransistor are minimized, the degradation of the isolator is due primarily to the LED which is more sensitive than the LED in the photodiode isolator. In contrast, at low ILED and high VCE, gamma-induced surface damage in the phototransistor is the dominant effect and the isolator is quite sensitive to irradiation.

C. E. Barnes

Papers

Thermal and Injection Annealing of Neutron-Irradiated p-Type Silicon between 76°K and 300°K

The Effects Of Radiation On Optoelectronic Devices

Permanent Damage Effects in Si and AlGaAs/GaAs Photodiodes

Neutron-induced trapping levels in aluminum gallium arsenide

The Effect of Gamma Irradiation on Optical Isolators