High energy Si implantation into GaAs is of interest for the fabrication of fully implanted, monolithic microwave integrated circuits. Atomic concentration profiles of 8, 12, 16, and 20 MeV Si have been measured using SIMS. The range and shape parameters have been determined for each energy. The theoretical atomic concentration profile for 12 MeV Si calculated using TRIM-88 corresponded to the SIMS experimental profile. No redistribution of the Si was observed for either furnace anneal, 825° C, 15 min, or rapid thermal anneal, 1000°C, 10 s. The activation of the Si improved when co-implanted with S. The co-implanted carrier concentration profiles did not show dopant diffusion. Peak carrier concentration of 2×1018/cm3 was obtained with a Si and S dose of 1.5×104/cm2, each.

The damage layer in unannealed Be+-implanted GaAs samples (45-keV Be+ ions, 1013 to 5 × 1014 ions/cm2) consists of a fine-grain mixture of amorphous GaAs and GaAs microcrystals, with the characteristic microcrystal size L of the microcrystalline component decreasing with increasing fluence. We have carried out reflectivity measurements on these samples for photon energies from 2.0 to 5.6 eV, in the electronic interband regime. Using Lorentz oscillator analysis and the effective medium approximation, we have extracted the dielectric function of the microcrystalline component (μ-GaAs) within the damage layer. The optical properties of μ-GaAs deviate appreciably from those of the bulk crystal near the interband absorption peaks. The linevidths of these peaks are found to increase over the bulk-crystal value by an amount proportional to (l/L), the increase being about 0.2 eV when L =100 Å. These finite-size effects can be understood in terms of a lifetime reduction caused by the short time it takes for electrons to reach the microcrystal boundaries.

Transport, Raman and XPS measurements were made on SI-implanted (1.7×1013cm−2, 50keV) and rapid-thermal annealed (100) and (211) GaAs substrates In an effort to distinguish differences between the two orientations. With these techniques, no significant differences were found. The implant-damage depth was about 1200Å for both orientations, with slightly higher near-surface damage (and lower mobility) apparent for (211). No unusual features in the (211) carrier concentration profile, as was previously reported, were evident.

High Resolution Transmission Electron Microscopy (HRTEM) has been used to obtain direct Information on the structure of damage clusters and in-depth radiation damage distribution in ion-implanted Ge and GaAs with Te+ and Si+ respectively, at doses far below the amorphization threshold. The observed changes in damage contrast in Te+ implanted Ge emphasize the existence of well defined separation between vacancies and interstitials in the lattice damage clusters. For GaAs an integrated “grey zone” was found as a typical effect of Si+ implantation.

Epitaxial InAs films have been grown on Si(100) substrates using triode ion-assisted deposition (TRIAD). The ratio r of the impinging Ar ion flux J to the deposited InAs flux was varied from 2.5 to 8.5 for Ar ion energies E from 5 to 55 eV. The growth temperature T was 350°C while the growth rate R was fixed at 0.6 μm/h. Two types of experiments were carried out. First, in order to investigate ion damage effects, X-ray diffraction rocking curve full-widths at half-maximum (FWHM) were measured as a function of E and r. In these experiments, the first 50 nm of InAs was always grown under the same conditions, r = 5 and E = 25 eV, in order to eliminate possible complicating effects caused by ion irradiation during InAs nucleation on Si, followed by 550 nm of growth at different E and r values. FWHM values increased with increasing E and r from 2800 arcsec, a value limited by defects arising from the 11% mismatch between InAs and Si, to 8900 arcsec as a result of ion damage. The FWHM value was found to be dependent on the total number of atomic displacements due to ion irradiation, estimated using a modified Kinchin-Pease expression. In the second set of experiments, E during the first 50 nm of growth was varied while ion irradiation damage in the remaining 5500 nm was minimized. Increasing E from 15 to 40 eV resulted in a decrease in the FWHM from 5500 to 2600 arcsec, followed by a gradual increase when E was increased above 40 eV. Ion irradiation at the onset of film growth thus reduced the propagation of defects from the InAs/Si interface into the film.

The ion bombardment effects of low energy molecular nitrogen ions (100eV) on GaAs have been investigated using in-situ polar angle dependent X-ray photoelectron spectroscopy. It was found that arsenic and gallium nitrides were formed as a result of the nitrogen ion bombardment. The ion bombardment also caused a depletion of arsenic in the near surface region. For example, with a dose of 6×1015 cm-2 of nitrogen molecular ions at 100eV, the surface structure can be described approximately as 1.5nm of Ga0.67A0.33N on GaAs. The ion bombardment moves the Fermi levels of both n-type and p-type GaAs to mid-gap. Heating the ion bombarded samples in a vacuum chamber to 500°C desorbs all arsenic nitrides but most of the gallium nitrides remain on the surface. The Fermi levels of both n-type and p-type are then stablized at about 0.4eV from the valence band maximum. A surface type-inversion of the n-type substrate is therefore induced by the nitrogen-ionbombardment/annealing treatment.

The purpose of the present work is to investigate p-CdTe thin films grown by ionassisted doping (IAD). Controlled doping in homo-epitaxial films resulting in carder densities up to 2×1017 cm-3 was obtained using P ions as the dopant. About 1.5% of the impinging P ions became electrically active in the films. Solar cells of n-CdS/p-CdTe were prepared and used as a diagnostic tool in understanding the p-CdTe films.

It has been a challenge to inject dopant atoms onto diamond lattice sites by ion implantation, because of the complications of ion damage and defect clustering during annealing. We re-investigated this topic by implanting boron ions into an insulating natural diamond ( type II-A ) which was predamaged by carbon ion implantation. Both of the implantations were performed at liquid nitrogen temperature. The amount of pre-damage was adjusted to produce enough vacancies and interstitials in diamond to promote boron substitutionality during subsequent annealing. Samples were characterized by optical absorption and electrical measurements. It was found that optical absorption of the implanted samples strongly depends on the post implant annealing sequence. The activation energies obtained from electrical measurements match very closely to those due to boron atoms in natural p-type diamonds. Photoconductivity measurements showed that the fraction of remaining electrically active radiation defects in the implanted and annealed samples depends on the relative fluences of boron and carbon.

Implantations of He and Ti were made into LiNbO3 and the H and Li profiles determined by elastic recoil detection (ERD) techniques. The loss of Li and gain of H depends upon the supply of surface H (surface contaminants or ambient atmosphere). For 50 keV He implants into LiNbO3 through a 200 Å Al film, the small Li loss is governed by the interface H. This is also the case for He implants into uncoated LiNbO3 in a beam line with low hydrocarbon surface contamination; similar implants under conditions of greater hydrocarbon deposition result in proportionally larger Li loss and H gain in the implant damage region. The exchange is possible only for those He energies, i.e., 50 keV, where the damage profile intersects the surface. For Ti implants Li is lost with little H gain. For this case the Li loss is believed to result from radiation-enhanced diffusion. Where He implantation is used to establish waveguiding in LiNbO3, the presence or absence of H in the implanted region is crucial with regard to refractive index stability, due to the replacement of H by Li from the bulk.

Ion implantation, annealing and channeling of single crystalline samples of KnbO3 and LiNbO3 have been studied. Raising the substrate temperature above 600 K, greatly increases the tolerance of the crystals for high-dose implantation. In LiNbO3 dynamic recrystallization has been observed for the first time.

ZnO thin films were deposited by ion-beam sputtering technique. Preliminary results show that the films are stoichiometric and crystalline in nature. The microstructure of ZnO films obtained depends very much on the process parameters. Among these parameters is the substrate temperature whose effect has been carefully examined.

ZnO films were deposited with substrate temperatures ranging from 200°C to 350°C. We observed that the sheet resistance of the films varies with their microstructure. In this investigation, a sheet resistance of 6.6 Mega-ohms per square is measured on a dense film deposited at a substrate temperature of 325°C.

We present in this paper a correlation between the film's microstructure and stoichiometry with some of it's electrical properties.

We report on the results obtained from a study conducted to understand the effect of reactive ion etching (RIE) of oxide films on the dopant diffusion in ion-implanted silicon. Thermally grown oxide films on silicon were plasma etched in a CHF3/CO2 plasma. The residual silicon surface damage created during plasma etching was removed by employing a low ion-bombardment, two-step surface plasma cleaning process. The samples with oxide films etched in a wet chemical etchant provided the control for evaluating the effect of the RIE process. The samples were implanted with boron and boron was activated under various conditions to form p-n junctions to obtain a range of boron doping profiles and junction depths. Some boron doped samples were implanted with arsenic to form a heavily doped n+ region at the silicon surface. The resulting doping profiles were analysed using spreading resistance profiling (SRP), four-point probe measurements, and secondary ion-mass spectrometry (SIMS) to understand the activation, diffusion, and precipitation of various dopants. Detailed transmission electron microscopy (TEM) analysis was used to study the microstructural effects. It was observed that plasma etching of the oxide films prior to the formation of boron diffused surface regions in silicon resulted in significant changes in boron diffusion. For low boron implant doses, plasma etched silicon surfaces resulted in retarded boron diffusion. For high boron implant doses, plasma etched silicon surfaces lead to enhanced boron diffusion.

Heat treatment of polyacrylonitrile leads to products with semiconductor to metal like conductivities. The electrical properties of these materials are further modified by ion implantation. It is noted that the conductivity (∼10-7 (Ω cm)-1) of heat treated Polyacrylonitrile at 435°C (PAN435) increases upon ion implantation with As+, Kr+, Cl+ of F+ reaching a maximum value of 8.9 × 10-1 (Ω cm)-1 at as does of 5 × 1016 ion/cm2 and an energy of 200 KeV for the case of F+ implantation. On the other hand, ion implantation of the more conducting heat treated PAN at 750°C (PAN750) leads to a decrease in the electrical conductivity of the material. It is proposed that the conductivity modifications are primarily due to structural rearrangements induced by the energetic ions. Specific chemical doping contribution to conductivity is noted for halogen implantation in PAN435. The temperature dependence of conductivity of PAN heat treated at 750°C suggests a two path conduction, namely, a three dimensional variable range hopping conduction and a metallic conduction. After ion implantation, the conductivity-temperature dependence is interpreted in terms of a variable range hopping conduction mechanism.

Rutherford backscattering (RBS) analysis of small-sized structures, fabricated by laser chemical vapor deposition (LCVD) with a focused laser beam and ion implantation with a focused ion beam (FIB), has been performed by a microprobe with focused 1.5 MeV helium ions. Micro-RBS spectra and RBS-mapping images revealed a local distribution of masklessly deposited Mo layers on GaAs and local doses of masklessly implanted Au atoms in Si.

We have produced beveled cross-sections of GaAs/GaAlAs multiple quantum well structures with inclination angles of 0.55 minutes of arc with a special ion beam etching technique. The extension of the damage which is induced during the dry etching process can be evaluated directly by a comparison of spatially resolved secondary ion mass spectroscopy and photoluminescence measurements. We observe a thickness of the damaged surface layer between 36 nm for 250 eV Argon ions and 160 nm for 1000 eV Argon ions in a GaAs/GaAlAs multiple quantum well structure.

The structure of silicon layers implanted with high current As’ beams at different power densities under self-annealing conditions (i.e. with simultaneous damage recovery activated by beam heating) has been investigated with Rutherford Backscattering and Transmission Electron Microscopy techniques. The results have been compared with previous ones obtained with P÷ implantation. They show that, in both cases, an ion-induced mechanism of recrystallization, characterized by an activation energy of the order of 0.3 eV, is operative at temperatures below the values necessary to activate thermal epitaxy. Chemical impurity profiles in samples self-annealed with As+ ions at high beam power density, show the occurrence of two relevant radiation-induced effects: i) diffusion enhancement in the tail region; ii) formation of two impurity peaks, separated by a depletion region centred at the ion projected range. While the deeper peak disappears with increasing irradiation time, the one located at the maximum of nuclear energy loss grows, apparently as a consequence of segregation of As atoms at large clusters of vacancy-type defects.