This work presents results of molecular dynamics simulations of the intermixing of a heterostructure formed by a Fe-Ag bilayer of thickness of few tens of Å. The intermixing is generated by As+ ions with energy of few eV. It has been found that the structure of the lattice has profound effects on mixing and disordering.

Ga droplet formation on GaAs(100) substrates milled by focused Ga ion beam is studied using scanning electron microscopy and scanning Auger microscopy. It is found that Ga droplet formation requires a threshold Ga+ dose of ∽ 1016/cm 2 and is closely correlated to the formation of Ga overlayer at the milled surface and the increase in Ga concentration by ∽ 32% in the subsurface region. The Ga droplet evolution appears to be driven by the instantaneous energy deposited continuously by the ions.

Experiments were conducted to determine the sample temperature dependence of ion-beaminduced in-plane stress in silicon. Implantations were carried out for B+, Ar+ and Ti+ at various dose ranges and different silicon temperatures. The ion-beam-induced surface stress was measured by using a newly developed technique, which has a high sensitivity. A large abnormal stress was observed for B+ implantation at room temperature. The results show that the silicon temperature has a significant effect on the ion-beam-induced stress. The influence of temperature on stress curves were presented. This effect is consistent with the temperature effect on the ionbeam-induced amorphization of silicon. However, the effect on chemically active ions, such as B+, is significant, indicating that some preferable temperature can be used for minimizing ionimplantation-induced stress.

Double crystal x-ray diffraction has been used to examine the lattice parameter changes which occur in heavily Si-doped GaAs obtained by ion implantation of 28Si at 180 keV with doses up to 1 x 1016/cm2. The heavily damaged, implanted layer was pulsed laser annealed with single pulses from a 10 ns dye laser operating at 728 nm with an energy density of up to 0.9 J/cm2. Plasmon Raman scattering was used at the center of the laser-annealed spots to determine the free electron concentration which reached ∼4 × 1019/cm3. Double crystal rocking curves were obtained for <400> reflections from the pulsed laser annealed area and from the surrounding as-implanted region. The results show a dilation of the lattice of up to 0.5% in the as-implanted region and in the laser-annealed region a dilation of 0.025%. The residual lattice dilation after annealing is interpreted in terms of a dilation due to free carriers and a (smaller) contraction due to the Si atomic size effects.

Damage induced in InP wafers by ion implantation has been investigated using Doppler broadening of annihilation radiation from variable-energy positrons (VEP), Rutherford backscattering/channeling (RBS), and room temperature photoluminescence (PL). Si* ions were implanted at 600 keV incident energy to total fluences from 1011 to 1014 ions cm−2. Annealing at room temperature was monitored for ∼100 days, during which both VEP and RBS showed recovery of the crystal toward the pre–implanted condition. RBS measurements of samples annealed at elevated temperatures showed that full restoration of lattice order occurred at 375 K, but VEP data for isochronal annealing up to 720 K showed only a moderate reduction in the vacancy–type defect concentration with a significantly narrower lineshape, consistent with vacancy clustering. PL measurements for MOCVD grown InP layers annealed up to 1100 K after implantation also indicated only moderate defect reduction.

An almost unexplored research field of the ion implantation processes is related to chemical modifications induced in a target by chemically reactive ions. This kind of chemistry is somewhat similar to the “hot atom” chemistry, where chemical transformations are produced by recoil atoms originating from nuclear reactions or radiative decay. XPS technique can provide unique informations on the chemical modifications produced by such processes. XPS results will be reported on silica glasses implanted with titanium, silver and tungsten ions in a dose range from l×1016 to 5×1016 ions cm−2, at energies ranging from 15 keV to few hundreds of keV. Most of samples were also subjected to a second implant with N ions. Radiation damage and chemical effects have been discriminated. Chemical compound formation as well as precipitation of the implanted species have been observed. Interestingly, evidences for reactions between chemical species obtained by the first implant and nitrogen (subsequently implanted) will be reported.

The implantation of Au into A1203 followed by thermal annealing at 1100°C leads to dramatic changes in the optical properties. The linear and nonlinear optical properties are correlated to the presence of small Au precipitates which form during annealing.

A special technique is described for in situ transmission electron microscope (TEM) experiments involving simultaneous ion irradiation, in which the resultant phenomena are observed as in a cross-section TEM specimen. That is, instead of ion-irradiating the film or foil specimen normal to the major surfaces and observing in plan view (i.e., in the same direction), the specimen is irradiated edge-on (i.e., parallel to the major surfaces) and is observed normal to the depth direction with respect to the irradiation. The results of amorphization of Si, irradiated in this orientation by 1 or 1.5 MeV Kr, are presented and briefly compared with the usual plan view observations. The limitations of the technique are discussed and several experiments which might profitably employ this technique are suggested.

PLZT 9/65/35 single crystals were irradiated with 1.5 MeV krypton ions at 25–450°C in the HVEM-Tandem Facility at Argonne National Laboratory. In-situ TEM was performed during irradiation in order to determine the critical amorphization dose. At room temperature, the material was completely amorphized after a dose of only 1.9×1014 ions/cm2, less than one fifth of the critical amorphization dose for silicon (1×1015 ions/cm2). The critical amorphization dose for the PLZT material increased with increasing irradiation temperature. At 450°C, amorphization was not observed after a dose of 1.1×10 15ions/cm2.

A new method for the characterization of high energy ion-implanted materials has been developed. The refractive index and thickness of the amorphous layer produced by ion-implantation as well as the recrystallized layer formed by annealing of the ionimplanted samples can be determined by means of this non-destructive optical technique.

For frequencies where the carriers do not respond, the measured reflectance is bilinear transformed, and further digital signal processing yields information about thickness and refractive index of the abovementioned layers. When working at optical frequencies where the carriers can respond to the electromagnetic field the physical position of the peak concentration follows directly from the processed reflectance data. Simulated and experimental data have been analyzed. The position of the boundaries between the amorphous, recrystallized and substrate zones, as well as the position of the carrier concentration peak can be determined for various steps of annealing. The algorithm has the advantage of being simple and time efficient.

The surfaces of thin films of tin dioxide prepared by radio frequency sputtering have been driven to react with nitrogen by exposure to a proton beam in an atmosphere containing nitrogen gas. Such modification of the composition of the free surfaces of the films modifies their gas response characteristics substantially.

The effects of modifying the surface of tin dioxide by exposure to proton beams in air have been demonstrated for thin films prepared both by tputtering and by dip coating with a sol.

The optical characteristics of polymethylmetacrylate (PMMA) can be changed selectively with the aid of ion implantation. This can be explained by the manner in which the chain molecules are decomposed by the bombardment. New binding states can be identified by means of XPS on the irradiated surface and traced throughout the implantation depth using dynamic SIMS. In order to avoid chemical reactions, inert gas ions, ranging from He to Xe, have been implanted at energies between 100 keV and 380 keV, and fluences from 1 × 1013 /cm2 to 7 × 1015 /cm2. The results indicate a correlation of the refractive index and the surface layer contraction with surface CH- and COH-groups generation (XPS) and with in-depth damage described by the emission of secondary ions with masses 26 and 42 (SIMS), assigned to (CH2)- and (C2OH2)-.

We have investigated oxygen ion implantation at substoichiometric doses for bandgap modification in silicon. Redistribution of the oxygen atoms during the high temperature anneal results in sharp interfaces aiding the formation of a heterojunction. A most interesting observation is the presence of donors in the vicinity of the implanted region, resulting in extensive counterdoping. Mesa type diodes on the implanted sample exhibit excellent rectification with a diode ideality factor n of 1.2 and a reverse saturation current density of 1 × 10−8 A/cm 2. The near surface region is shown to be crucial for achieving the high rectification behavior.

Nitrogen ion implantation was performed to enhance the nitrogen content of non-stoichiometric AlNXOY film (x < 1.0), which was prepared via reactive RF sputtering. A method called plasma immersion ion implantation (P111) was employed to perform the nitrogen implants. The implanted films were studied for changes in film composition using Rutherford Backscattering (RBS). Optical absorption behavior of the films was analyzed using a Perkin-Elmer monochrometer, and electrical characteristics were measured using both high frequency capacitance-volltage (CV) and current-voltage (IV) measurements. The implanted films were subsequently rapid thermal annealed in a nitrogen atmosphere from 550°C to 1060°C, and the resulting effects on the AlNXOY film were investigated using the aforementioned techniques.

Crystallization induced by proton beam irradiation using large area ion implantation at low temperature (less than 600°C) have been investigated. Phosphine gas containing hydrogen of more than 95% is discharged by RF power of 100W. Both phosphorus ions and protons are accelerated by a potential of 100kV and implanted into polycrystalline silicon (poly-Si) layers. At a range of beyond 2×1015 ions/cm2 P1 ions dose, amorphous phase is primarily formed and then changes into polycrystals again and its grain sizes grow up to 50nm in average diameter. The crystallization is found to occur simultaneously with phosphorus doping and to depend on the amount of the irradiated protons. This technique enables us to eliminate the activation annealing process for implanted dopant.

Layers of TiN have been developed on pure titanium samples using pulsed ion beams generated with a Plasma Gun operated in the detonation mode.

XPS analyses show TiNx formation in depths >0.6μm, with stoichiometric x>0.8. The efficient TiN formation in this process can be attributed to the fast energy released by the pulsed beams, which can increase the surface layer temperatures at a ∼15K/ns rate, generating thermal gradients of ∼1500K/μm. This thermal effect can help the titanium getter effect on the nitrogen plasma bubble.

Ion implantation and ion mixing are applied to improve the corrosion behavior of two uranium alloys: UV0.2 and UTi0.75, in three specific media: hydrogen, humid air and salt fog. This experiments shows particularly that high dose nitrogen implantation might be effective for both corrosive environment, hydrogen and humid air. Ion mixing of aluminum coatings on UTi0.75 alloy induces microcracks in these films and reduce their protective characters in salt fog medium.