Temperature Ion Implantation Research Articles

Absorption and cathodoluminescence properties of Cu implanted SrTiO 3

Single crystal of SrTiO 3 (STO) has been implanted at room temperature with 200 and 400 keV Cu ions to doses ranging from 1×10 16 to 1×10 17 ions/cm 2. The temperature cathodoluminescence (CL) of Cu implanted SrTiO 3 has been studied in order to clarify the role of them in luminescence. Therefore CL measurements made on SrTiO 3 implanted with metal ions are reported at 300 K with different excitation modulation frequencies. Room temperature ion implantation into surface layer changes low temperature CL signals both in terms of their relative intensities and also modifying the emission spectra. For such a large ion dose the unusual aspect is that the signals are still recognisable. The details of such changes and modifications of emission spectra are reported and discussed. A particularly important result is that the CL demonstrates that the implants cause bulk relaxations of the material that are apparent via the rear face CL.

High Temperature Ion Implantation: a Solution for n-Type Junctions in Strained Silicon

Elastic strain intentionally applied to thin layers can be reduced or even completely relaxed by amorphization during ion implantation. Sb implantation and activation in unstrained and strained-SOI substrates and effects on the crystal quality for different implantation conditions were investigated. Implantation induced amorphization can be avoided and simultaneously high dopant activation up to 55% can be achieved by implanting at elevated temperature. For a low implantation energy of 6 keV, no dopant profile broadening is measured after dynamic annealing in strained-SOI.

Quantitative analysis of the lattice reconstruction of ion-implanted SiC after visible light laser irradiation

We report on a quantitative analysis of the effect of visible light laser irradiation (VLLI) on hexagonal (α) silicon carbide implanted with nitrogen and aluminum. In both cases of 4H and 6H polytypes we show that a short, but intense, irradiation with the 532 nm wavelength of a frequency-doubled neodymium: ytterbium aluminum garnet (Nd:YAG) laser results in a substantial reduction in the damage level produced by room temperature ion implantation. Up to now the recovery could not be made complete but, in the best conditions, it could reach ∼80% of the initial damage value. This is not enough to qualify VLLI as a full activation step but, rather, suggests to use it as a new processing tool in order to lower the constraints of high temperature ion implantation or, after implantation performed at room temperature, to reduce the total budget for high temperature annealing and activation steps.

Local structure of Fe incorporated in GaInP layers by high temperature ion implantation

We have performed a structural investigation of the atomic environment of Fe impurities introduced by high temperature ion implantation in MOVPE grown GaInP layers. The lattice location of the implanted Fe atoms has been investigated by means of proton-induced X-ray emission in channeling geometry while X-ray absorption spectroscopy measurements have been performed to study the Fe local structure. The effect of post-implantation thermal treatments and the role of the substrate doping have been studied and discussed in comparison with the results obtained for Fe implantation in InP. An increased thermal stability of the substitutional Fe atoms in the GaInP lattice with respect to InP has been observed, whereas no effect related to the n-doping has been pointed out.

Investigation of indium diffusion process in In + ion implanted GaAs

Rutherford backscattering (RBS) has been used to determine diffusion coefficients of indium atoms in semi-insulating (1 0 0) GaAs implanted with 250 keV In + ions at a fluence of 3×10 16 cm −2 and isobarically annealed at 600 and 800 °C temperature. Computer modeling of the indium depth profiles based on Ga vacancy-mediated diffusion has shown good agreement with the RBS experimental results. Self-annealing effect was confirmed to play an important role due to high defect mobility at room temperature ion implantation. Large values of the In diffusion coefficients obtained in the present study, in comparison with the literature data for unimplanted GaAs, confirms strong enhancement of the diffusion process by radiation damage.

High Dose High Temperature Ion Implantation of Ge into 4H-SiC

A box like Ge distribution was formed by ion implantation at 600°C. The Ge concentration was varied from 1 to 20 %. The TEM investigations revealed an increasing damage formation with increasing implantation dose. No polytype inclusions were observed in the implanted regions. A detailed analysis showed different types of lattice distortion identified as insertion stacking faults. The lattice site location analysis by “atomic location by channelling enhanced microanalysis” revealed that the implanted Ge is mainly located at interstitial positions.

Ion beam analysis of Cs-implanted zirconia and spinel

Fission products (Cs) were introduced into yttria-stabilized zirconia (YSZ) and magnesium aluminate spinel (MAS) single crystals by room temperature ion implantation. The effect of high-temperature annealing on the depth distribution of implanted species and the surface homogeneity of crystals were investigated by the combination of AFM and RBS using a macro- and a micro-ion beam. The diffusion and release of Cs involve mechanisms which depend on the material and Cs concentration. In YSZ Cs desorbs out of the crystal at lower temperature (∼550°C) than in MAS (∼850°C). In YSZ the surface of the sample remains unaltered when Cs desorption occurs, whereas in MAS Cs desorption is accompanied by the exfoliation of the sample surface.

Ion beam analyses and electrical characterization of substitutional Fe properties in Fe implanted InP

We have investigated the structural and electrical behavior of Fe centers introduced in InP by high temperature ion implantation. The effect of post-implantation annealing treatments on the crystal damage and the lattice location of the Fe atoms was studied by PIXE-RBS-channeling measurements. Current–voltage measurements and simulations were used to characterize the electrical properties due to the presence of Fe-related deep traps. The results show that the background n-doping density plays a crucial role in controlling the annealing behavior and the electrical activation of the Fe centers.

Mechanical and tribological properties of carbon and nitrogen consecutive ion implantation into aluminium

Mechanical and tribological properties of successive C and N ion implantation into Al were studied in the present work. Ion sequence, substrate temperature and subsequent thermal treatment were performed in order to understand the involved mechanisms on the surface hardening. The results showed that independent of the ion sequence, a higher surface hardness is obtained for room temperature ion implantation (≈ 10 GPa). At high substrate temperature the hardness decreases to 7 GPa. The hardening mechanisms are discussed in terms of: solid solution, hard embedded precipitates in the soft Al matrix and the damage produced by the ion implantation process. Adhesive and abrasive regimes are identified from the friction coefficient profiles and are function of the ion implantation parameters. Wear resistance is improved if subsequent thermal treatment at high temperature is performed. Wear improvement is correlated to the presence of a high concentration of carbon clusters in the Al matrix.

Incorporation of active Fe impurities in GaInP by high temperature ion implantation

Single GaInP layers, grown by MOVPE lattice matched to GaAs, were implanted with Fe at T=200°C and annealed at 450 or 600°C. The role of implantation temperature and fluence in determining the crystal damage, and the damage recovery by annealing are investigated by RBS-channeling measurements. The redistribution of the Fe atoms is studied by means of SIMS depth profiling. The electrical properties related to Fe implantation are studied by current–voltage measurements. The results allow a first analysis of the similarities and the differences showed by the Fe implanted GaInP with respect to the InP case.

Use of the nuclear microprobe for the characterization of ion-implanted spinel

Stable analogues of a toxic fission product (Cs) were introduced into magnesium aluminate spinel single crystals by room temperature ion implantation. Changes in the atomic concentration of Cs atoms upon annealing at high temperature were monitored by Rutherford backscattering (RBS) experiments using a nuclear microprobe. Results show that Cs atoms are inhomogeneously distributed in the crystal after annealing; they are collected in islands with a size of a few tens of micrometers. The remaining crystal exhibits a very small Cs concentration due to the exfoliation of the implanted layer.

The influence of the ion implantation temperature and the dose rate on smart-cut© in GaAs

The temperature and dose rate dependence of the smart-cut© process in GaAs have been investigated in this paper. The distribution of hydrogen and the implantation damage in the samples were studied by ion beam analysis and X-ray diffraction. It was found that at higher temperatures, hydrogen is mobile in the lattice and can rearrange into the platelets, microcracks and bubbles which are present in blistered material, thus relieving the strain in the lattice. The dose rate was also found to be significant for the smart-cut process, as blistering and exfoliation are inhibited at low dose rates.

The influence of the ion implantation temperature and the flux on smart-cut© in GaAs

The dependence of hydrogen flux and substrate temperature during implantation on the smart-cut© process in GaAs have been investigated in this paper. The lattice disorder in the samples was studied by ion beam analysis. It was found that both the flux and the implant temperature are significant for the smart-cut process. As the flux increases, the degree of exfoliation and the mean blister size increases, while the number density of blisters falls, indicating that blister evolution is enhanced at high dose rates.

Synthesis of single-phase carbon nitride film prepared by hot implantation

High temperature ion implantation (hot implantation) is used to synthesize carbon nitride (CN x ) films. Three CN x films are compared by near edge X-ray absorption fine structure (NEXAFS) spectroscopy; one is prepared by room temperature implantation, another is prepared by subsequent annealing, and the other is prepared by hot implantation. The former two films show three comparable discrete peaks in N K-edge NEXAFS spectra, which are assigned to different kinds of local structures at N sites. On the other hand, a single peak grows predominantly in the spectra for the film prepared by hot implantation. Through the polarization dependence analysis of NEXAFS, the dominant peak is assigned to the fullerene-like structure of CN x which consists of pentagons and hexagons. The difference between the CN x films which are synthesized by subsequent annealing and hot implantation is also discussed.

Role of the Substrate Doping in the Activation of Fe2+ centers in Fe implanted InP

AbstractWe have investigated the structural and electrical behavior of Fe centers introduced in InP by high temperature ion implantation. The lattice location of the Fe atoms and the effect of postimplantation annealing treatments have been studied by PIXE-channeling measurements. I-V, CV and DLTS analyses have been used to characterize the electrical properties related to the presence Fe2+/3+ deep traps. The results show that the background n-doping density play a crucial role in controlling the annealing behavior and the electrical activation of the Fe centers. The same effect has been observed in samples containing Fe concentrations both above and below the Fe solubility threshold in InP.

Effects of the ion-implantation on the thermoluminescence spectra of strontium titanate

Thermoluminescence of strontium titanate at low temperature is characterised by long wavelength emission centred near 800nm which contains at least three overlapping luminescence bands. The thermoluminescence is excited by X-ray irradiation at 25K of an entire sample. Room temperature ion-implantation into the surface layer changes the low temperature TL signals both in terms of their relative intensities and peak temperatures, as well as modifying the emission spectra. Such an intense perturbation of the bulk signals resulting from surface ion beam implantation is extremely unusual. However, it is well documented that for strontium titanate there are a variety of low temperature relaxations of the structure, and even phase transitions, which are highly sensitive to the presence of intrinsic defects, impurities and stresses.The ion-implantation damage in the surface is thus thought to act as a stress nucleation zone from which such relaxations can propagate throughout the entire crystal. There are consequent changes in the thermoluminescence in terms of defect stability and glow peak temperature. Details of such changes and modifications of emission spectra are reported.

Nanoparticle fabrication for micro total analysis system by using ion implantation and surface etching

Gold nanoparticles can be used as a catalyst when deposited on a material surface. Adhesion to the support surface is a problem, however, and thus prevents the particles from being an effective catalyst. Adhesion in specified microscale regions is needed in recently developed micro total analysis systems (μ-TAS) and other microchemical systems such as “lab on a chip”. Both types of systems have channels, mixers, reactors and analyzing devices. The mixer and reactor devices use chemical reactions and therefore need a catalyst. We previously developed an adhesion process for gold nanoparticles that involves ion implantation and surface etching. In this process, which is called the IISE (ion implantation and surface etching) method, a silicon substrate as a support surface is etched after gold ions (3.1 MeV) are implanted, resulting in gold particles adhering to the support. The catalytic performance of nanoparticles, however, depends on the particle size. To determine the particle size for optimal catalytic performance in μ-TAS, in this study, we used the IISE method to fabricate gold nanoparticles at different ion implantation temperatures, ion doses and etch times. Results showed that the nanoparticle size was independent of implantation temperature, but increased slightly with increasing ion dose and increased significantly with increasing etch time. An ion dose exceeding 3×10 16 cm −2 yielded approximately 10-nm diameter nanoparticles. In conclusion, by adjusting the etch time, the IISE method showed good controllability of particle size and concentration.

Effects of hydrogen implantation temperature on ion-cut of silicon

We have studied the effect of ion implantation temperature on the nature of cleavage and layer transfer, and the electrical properties in hydrogen implanted p-Si. The lattice damage and the hydrogen concentration in the as-implanted Si and transferred Si films were analyzed with elastic recoil detection, respectively. Implantations performed at −140 °C [low temperature (LT)] and room temperature (RT) resulted in a variation in the thickness and surface morphology of the transferred layers. The transferred layer from room temperature hydrogen ion implantation was both thicker and atomically smoother than the transferred layer produced by −140 °C hydrogen implantation. The as-transferred layer obtained from RT-implanted p-Si wafer was n-type, but converted to p-type after annealing at 650 °C or higher. The transferred layer obtained from LT-implanted Si wafer was highly resistive even after high temperature annealing. These variations were observed to be correlated with the damage profiles measured by ion channeling; channeling data showed that the room temperature implantation provided a deeper and narrower damage distribution than that obtained from the −140 °C implantation. The nature of the implantation damage was evaluated with the aid of IR spectroscopy and was found to consist of Si–H defects. The type and population of these defects were observed to be dependent on the ion implantation temperature. In both room temperature and −140 °C implantations, the presence of the implantation damage facilitated the nucleation of Si–H defects that developed into H platelets, which were the precursor defects for the cleavage and the layer transfer.

Incorporation of Highly Concentrated Iron Impurities in InP by High Temperature Ion Implantation

AbstractIron was introduced in InP by ion implantation with the aim of obtaining a high concentration of substitutional, electrically active, deep level impurities. A substrate temperature higher than 200 °C was maintained during implantation in order to reduce damage accumulation and Fe defect reactions. The lattice position of the implanted Fe atoms and its modification during annealing treatments was studied by means of Proton Induced X-ray Emission (PIXE) in channeling conditions and correlated with the ion induced damage measured by different techniques. The results show that a high fraction of substitutional Fe atoms is present after the implantation. This fraction is progressively reduced during thermal treatments by increasing the annealing temperature, with the formation of inactive Fe aggregates, probably in the form of small Fe-P complexes.

Cesium Ion Implantation in Single Crystal Yttria-Stabilized Zirconia (YSZ) and Polycrystalline MgAl2O4-YSZ

ABSTRACTYSZ and MgAl2O4-YSZ composite are two promising materials as in the inert matrix nuclear fuel for the incineration of plutonium. In this study, 400 keV Cs ions were implanted to a fluence of 1×1017 ions/m2 in both materials in order to investigate the retention behavior of fission product at elevated temperature. The implantations were completed at room temperature for the YSZ and 973 K for MgAl2O4-YSZ, respectively. Subsequent annealing at 1273 K was performed after a room temperature implantation of YSZ. After annealing, a high density of gas bubbles formed with diameter from 3 to 40 nm from the surface to a depth of 150 nm in the YSZ matrix. The swelling due to bubbles formation was estimated to be 2.5%. In situ TEM was employed during high temperature ion implantation of the MgAl2O4-YSZ composite. A high density of small bubbles with 5 nm in diameter formed in the MgAl2O4 and YSZ grains after an ion dose of 1×1017 ions/cm2. There was no preferential precipitation along grain boundaries. Electron Paramagnetic resonance (EPR) spectroscopy was used to investigate the type of defects that formed in the YSZ matrix.