E. P. EerNisse

Erratum: Role of integrated lateral stress in surface deformation of He‐implanted surfaces

The first measurements of integrated lateral stress S have been obtained for He implantations to fluences where surface deformation occurs. Implants into Mo, Nb, and Al were carried out at room temperature. The low‐fluence results provide values for the induced volume expansion per implanted He atom. The high‐fluence results demonstrate that blistering, as observed in Mo and Nb, is directly related to relief of S. However, flaking, as observed in Al, does not result in appreciable relief of S. The saturation value of integrated lateral stress, Smax, is proportional to yield stress for the three materials and is independent of the He projected range. A model to describe the blistering phenomenon is developed based on the standard elastic stability equation for a plate subjected to in‐plane forces. This elastic instability model uses only measurable material parameters and does not depend explicitly on the behavior of He in the material. The model explains the τ∝d2/3 relation observed for blister diameter d...

Introduction rates and annealing of defects in ion‐implanted SiO2 layers on Si

The introduction rates and isochronal annealing behavior of structural defects created by atomic collision or ionization in SiO2 layers thermally grown on Si in O2 and steam are investigated by measuring the induced volume compaction for ion and electron bombardments. The use of compaction measurements permits study of the introduction and annealing of defects with little confusion from changes in the charge state of the defects. The structural damage created by ion energy deposited into atomic collisions is found to be complex, possibly consistent with a thermal process involving reordering of the noncrystalline network of Si–O tetrahedra, and to anneal in a slow featureless manner beginning around 300°C and returning to the original density near the original growth temperature. The structural damage created by ion or electron energy deposited into ionization is identified with broken Si‐O bonds and found to anneal completely in a single well‐defined stage centered at 650°C. The ionization‐induced struct...

Ionization dilatation effects in fused silica from 2 to 18‐keV electron irradiation

We have used low‐energy electron irradiations in conjunction with a bending‐cantilever‐plate technique to investigate the volume dilatations produced by ionization effects in fused silica. Our irradiations generally cause compaction in agreement with previous data from high‐energy electron irradiations, but we consistently observe a slowly saturating compaction‐dose relationship rather than the sublinear power‐law relationship seen in the high‐energy data. Our results show agreement with the apparent ionization compaction effect extracted from low‐dose‐rate 1H+‐ion‐implantation experiments. We find no dose‐rate dependence in the electron ionization compaction effect, in marked contrast with the apparent ionization compaction effect in the implantation experiments. We therefore conclude that the enhancement of the apparent ionization compaction effect at high dose rates in the implantation experiments results from an interaction between the ionization and the atomic displacements accompanying the implanati...

Volume expansion and annealing compaction of ion‐bombarded single‐crystal and polycrystalline α‐Al2O3

Radiation damage of α‐Al2O3 was systematically investigated as a function of incident ion mass and energy partitioning into atomic and electronic processes by measuring the resulting stress in the ion‐bombarded layer with a cantilever beam technique. Heavy‐ion‐bombardment‐induced expansion in the implanted surface layer shows strong anisotropy which appears to be related to the higher defect production rate along the c axis. Stress relief is observed at fluences above 1×1015 Ar/cm2 for the [0001] orientation only and is attributed to basal slip. Hydrogen bombardment subsequent to heavy‐ion bombardment results in compaction which is also anisotropic. The anisotropy of both the expansion and the compaction point to structure sensitive defects. Approximately 80% of the radiation damage is annealed at 900 °C for the [0001] orientation and 60% for the [0110] orientation. A similar expansion‐compaction response is found in argon‐ and hydrogen‐bombarded polycrystalline Al2O3.

Stress in ion‐implanted CVD Si3N4 films

The compressive stress buildup caused in chemical‐vapor‐deposited (CVD) Si3N4 films by ion implantation is shown to be caused entirely by atomic collision effects, ionization effects being unimportant. The stress introduction rate is shown to be independent of CVD processing variables and O content of the film. The maximum attainable compressive stress change is 3.5×1010 dyn/cm2, resulting in a maximum net compressive stress of 2×1010 dyn/cm2 for films on Si where the as‐deposited films inherently have 1.5×1010 dyn/cm2 tensile stress before ion implantation. Results are presented which show that O in the films inhibits thermal annealing of the ion‐implantation‐induced compressive stress. Results for introduction rate and annealing effects are presented in normalized form so that workers can use the effects for intentional stress level adjustment in the films to reduce probability of cracking and detachment.

Extension of the double resonator technique

The application possibilities of the double resonator technique for simultaneous thin‐film areal mass density and integrated lateral stress measurements have been expanded by removing the requirement of equal film thicknesses on both resonators. Several situations with either or both of the integrated stress or the areal mass density being proportional to film thickness are treated. The new equations are tested with Er metal film deposition and hydriding results.

Carrier trapping and recombination in avalanche diodes

The differential equations describing an avalanching p+nn+junction in the presence of multiple-level carrier traps have been solved numerically for trap densities as high as two orders of magnitude greater than the n-region background doping. The results compare quantitatively with a number of past, as well as new, experimentally observed changes in avalanche microwave diode performance with neutron damage. In particular, trapped charge in the space-charge region tends to localize the avalanche region near the p+n junction, which raises the frequencies of operation. Carrier trapping at the edges of the space-charge region explains the increase in operating voltage and decrease in small-signal capacitance. The localization of the avalanche region, through carrier trapping in the space-charge region, and recombination effects at high avalanche current densities combine to cause eventual RF failure of IMPATT and TRAPATT diodes with neutron damage.

Electromorphic ceramics in extreme environment parametric device applications

Diffuse-transition electromorphic ceramics have been investigated for parametric device applications in extreme temperature and radiation environments. The circuit properties of nonlinear capacitors fabricated from such materials were found to be relatively constant over a temperature range of hundreds of degrees centigrade and extremely insensitive to nuclear radiation. Because of dielectric relaxation behavior, efficient parametric device applications are limited to below 10 MHz with presently available materials. An antiferroelectric composition provided more efficient parametric amplification at the higher frequencies than did the ferroelectric compositions investigated.