Erbium doping of silicon and silicon carbide using implantation followed by ion beam induced epitaxial crystallization (IBIEC) is investigated. The implanted concentration of Er was 1.4 at% in both cases. In Si(100), Rutherford backscattering/channeling revealed that about 40% of the Er atoms evolved upon rapid thermal annealing from an undetermined position (room temperature) to an interstitial tetrahedral position (650°C) and finally to a substitutional position (950°C). The remaining Er atoms were presumably trapped in the small precipitates visible in high resolution transmission electron microscopy. The photoluminescence at 1.54 μπι of Er3+ is enhanced with annealing and persists up to room temperature after a 950 °C 1 min anneal. The high concentration of optically active Er atoms is illustrated by the lack of saturation of the photoluminescence at high pumping excitation intensity. Erbium was also implanted into cubic silicon carbide films prepared by chemical vapor deposition on Si at 900 °C. Both solid phase epitaxy (SPE) and IBIEC were performed. After a 950°C anneal, the low temperature photoluminescence at 1.54 μιη after IBIEC was five times higher in SiC than in silicon. The difference in photoluminescence linewidth between IBIEC (broad lines) and SPE (sharp lines) is explained in terms of interactions between optically active erbium atoms.

A study has been made of the luminescence during Tb-ion implantation in Al2O3 or by Ar- or He-ions bombardment to Tb-ion implanted Al2O3. The substrates used were colorless and transparent single crystal ɑ-Al2O3 with (0001) or (1102) surface orientation. Ion implantations of Tb-ions in Al2O3 were carried out at fluences of 1x1013 to 1x1017 Tb/cm2 at 100 keV at nearly room temperature. Change in color of Al2O3, substrates by Tb implantation was invisible to the naked eye. The luminescence spectra were measured by Ar (100 keV) or He (50 keV) bombardment to Tb implanted Al2O3 or during Tb implantation into Al2O3 using a spectroscopy with three optical filters and photomultiplier. The luminescence spectra during Tb implantation into AljOj have four clear peaks identified as emission due to D-F transitions of Tb3+ state. The luminescence spectra of Tb implanted A12O3 excited by He, Ar and Tb bombardment were almost the same except for the luminescence at the wavelength ranging from 300 to 450 nm, which is caused by strong emission from A12O3 itself. The peak of the luminescence appears at 550 nm, and its intensity depends on the Tb dose. The maximum intensity of luminescence during Tb implantation at room temperature is obtained as the maximum atomic ratio of implanted Tb is 2–3 atomic %.

Metal nanocluster-glass composites demonstrate unique optical properties and significant nonlinear response. In this work nanometer dimension metal colloids were formed in silica by sequential implantation of Ag and Cu ions. The Ag and Cu were implanted with relative ratios of Ag to Cu of 9:3,6:6, and 3:9 at a total nominal dose of 12xl016 ions/cm2. TEM techniques were used to examine colloid size and size distributions. The linear optical response was measured from 200 to 900 nm, while the nonlinear optical properties were measured using the z-scan technique at a wavelength of 570 nm. The linear and nonlinear optical properties were found to be dependent upon the ratio of sequentially implanted Ag to Cu and are consistent with effective medium theory.

Twelve different elements used for doping or isolation were implanted into GaN, (and selected species into A1N and InN), and the resulting range parameters were measured by Secondary Ion Mass Spectrometry. For lighter elements such as Be, F and H the agreement between experimental range and range straggle dtermined using a Pearson IV computer fitting routine and those predicted by TRIM 92 calculations was good, but for heavier elements such as Ge and Se the discrepancy can be as much as a factor of two in range. There was little redistribution of any of the investigated species up to 700 °C, except for 2H in A1N and S in GaN. Elements such as F and Be which are generally rapid difiusers in III-V compounds do not display any redistribution in GaN for temperatures up to 800 °C.

Effects of low energy ion beam induced damages on transport properties of a two-dimensional electron gas (2DEG) system in GaAs/AlGaAs heterostructures have been investigated. 1 keV Ar ions were irradiated on the sample surface at several ion doses (1011 - 1013 cm-2). Carrier density and electron mobility of the 2DEG formed at about 90 nm below the GaAs/AlGaAs heterostructure surface were estimated at 1.5 K by Hall resistance and longitudinal resistance measurements before and after annealing at 400°C for 10 min in an Ar gas ambient. The temperature dependence of those values was also measured for as-grown and for 1013 cm-2 ion irradiated and subsequently annealed samples. Typical results show that carrier density and mobility are not degraded severely by Ar ion irradiation at doses of 1013 cm-2 and suggest the possibility to fabricate buried structures in GaAs/AlGaAs heterostructures using low energy Si focused ion beam (FIB) irradiation and subsequent in situ overlayer growth by MBE.

Homogenous, epitaxial buried layers of 3C-SÍC have been formed in Si(100) and Si(lll) by ion beam synthesis (IBS) using 180 keV high dose C ion implantation. It is shown that an annealing temperature of 1250 °C and annealing times of 5 to 10 h are sufficient to achieve well-defined Si/SiC/Si layer systems with abrupt interfaces. The influence of dose, annealing time and temperature on the layer formation is studied. The favourable dose is observed to be dependent on the substrate orientation. IBS using 0.8 MeV C ions resulted in a buried SiC precipitate layer of variable composition.

We studied high-dose implantation of tungsten into 6H-silicon carbide in order to synthesize a highly conductive surface layer. Implantation was performed at 200 keV at room temperature. Subsequently, the samples were annealed in two steps at 500°C and 700°C or 950°C, respectively. The influence of dose and annealing temperature on the reaction of W with SiC was investigated. Rutherford Backscattering Spectrometry (RBS), X-Ray Diffraction (XRD) and Auger Electron Spectroscopy (AES) contributed to study structure and composition of the layer as well as chemical states of the elements. During implantation sputtering became significant at a dose exceeding 1.0×1017 W+cm−2. Formation of tungsten carbide and suicide was observed already in the as-implanted state. An annealing temperature of 950°C was necessary to crystallize tungsten carbide. However, tungsten suicide remained amorphous at this temperature. Therefore, a mixture of polycrystalline tungsten carbide and amorphous tungsten suicide evolved under these conditions. The resistivity of such a layer implanted with 1.0×1017 W+ cm−2 and annealed at 950°C is 565 μΩcm.

The experimental conditions during the implantation step of Ion Beam Synthesis influence crucially the formation of a buried structure in subsequent annealing steps. Due to of the complexity of the in-beam nucleation and evolution of precipitates of new phases there is still a low level of understanding. In this paper we present results of direct experimental investigations as well as results of computer simulations of in-beam nucleation and growth. The evolution of an ensemble of C0SÌ2 precipitates is mainly controlled by nucleation and diffusion. The observed decrease of the nucleation rate at high fluences can be explained by the decrease of the supersaturation of implanted atoms due to diffusion towards earlier nucleated precipitates.

Single crystal samples of (100) oriented yttria stabilized cubic zirconia are implanted with Pt ions to doses up to 6x1017 /cm2. Our previous studies showed that the retained Pt dose was too small due to the sputter limit. To overcome this problem, a C film was deposited on the surface of some samples before implantation. The implanted samples were annealed isothermally in air at 400°-1200°C, and were analysed with RBS-C and TEM. The C-layer has been found to be very effective for protecting the sample surface from sputtering and thus increasing the Pt concentration by a factor of two, up to 33 mol.% Pt. The as-implanted Pt was non-substitutional. After annealing at 1200°C for 1 h, Pt diffused to large depths, and showed a substitutional fraction of about 23%. The detailed TEM measurements on the microstructure and damage of the implanted layer show that after annealing at these temperatures the recovery of ion damage is incomplete. Pt atoms undergo substantial migration concurrently. The Pt at first dissolves in the matrix (though not substitutionally), diffuses and precipitates again at high temperature.

A metastable C-Si-N compound has been synthesized by high dose N+ implantation into polycrystalline /8-SiC (cubic phase). The thin films formed upon 100 keV implantations were characterized with respect to various ion doses and target temperatures. X-ray diffraction with a position-sensitive detector and cross-sectional transmission electron microscopy revealed that the as-implanted surfaces contained ∼0.15 jttm thick continuously-buried amorphous layers. Rutherford backscattering spectroscopy showed that the peak concentration of nitrogen saturated up to approximately 54 at. % with increasing doses, suggesting a new phase formation.

Hetero-structures of GeSi layers on Si have been produced by high dose Ge implantation into p-type (100) Si wafers at 150 or 300 keV at various doses. From spreading resistance profiling measurements, it is found that for samples implanted at 300 keV at a sufficiently high dose, there is an unexpected resistivity type conversion due to the Ge implantation. The depths of the n-p junction formed as-implanted can be larger than 1.5 /xm, far beyond the Ge projected range. Upon annealing, the junction position moves toward the surface and eventually stops at a depth corresponding to the thickness of the GeSi layer. However, no such n-p junction formation was observed in the spreading resistance profiles of the 150 keV implanted samples. These spreading resistance results are discussed in conjunction with results from RBS and SIMS experiments.

Si (100) wafers were implanted with Al at 500°C to high doses at multi-energies and were oxidized in 1 atm flowing oxygen at 1000°–1200°C. The morphology, structure, and oxidation behavior of the implanted and oxidized Si were studied using optical microscopy, atomic force microscopy, and cross-sectional transmission electron microscopy in conjunction with selected area electron diffraction and energy dispersive x-ray analysis. Large Al precipitates were formed and embedded near the surface region of the implanted Si. The oxidation rate of the Al-implanted Si wafers was lower than that of virgin Si. The unique morphology of the implanted Si results from rapid Al diffusion and segregation promoted by hot implantation. The reduction of the oxidation rate of Si by Al implantation is attributed to the preferential oxidation of Al and formation of a continuous difiusion barrier of Al2O3.

Raman scattering was used to assess the lattice damage caused by Si+ implantation in InP, as well as the lattice recovery achieved after rapid thermal annealing (RTA). Semi-insulating InP was implanted with Si+ with doses in the range of 1012 to 5xl014cm”2. Raman scattering measurements show a progressive intensity reduction of the characteristic first- and second-order InP Raman peaks and an enhancement of the disorder activated modes with increasing dose. The onset of amorphization was found to be at about 1014 cm”2. RTA of the implanted samples at 875 °C for 10s results in a very good recovery of the InP lattice even for the highest dose, as confirmed by Raman scattering measurements.

Radiation-induced damage and strain in AlxGai-xAs (x=5 to 1) were investigated by measurements of the lattice parameter using x-ray diffraction. Irradiations employed MeV C, Ar and Au ion beams with a substrate temperature of 80 K. For samples with high Al content, the out-of-plane lattice parameter increased with fluence at low doses, saturated, and then decreased to nearly its original value. The in-plane lattice parameter did not change, throughout. These results were independent of the irradiation particle when scaled by damage energy. For the Al.5Ga.5As samples, however, the out-of-plane lattice parameter increased monotonically with dose to large strains until the layer amorpnized. Selected samples were examined by high resolution and conventional transmission electron microscopy (TEM). Channeling Rutherford backscattering spectrometry (CRBS) was also employed to monitor the buildup of damage in many samples. Recovery of the lattice parameter during subsequent thermal annealing was also investigated.

Diamond is subject to oxidation if exposed to oxygen while at temperatures above approximately 600°C. A method has been demonstrated for protection of diamond against oxidation by employing Si+ ion implantation to transform a thin surface layer into silicon carbide which exhibits excellent oxidation resistance. Integral SiCx oxidation barrier layers have been formed on diamond using high Si+ dose levels and high temperatures during implantation. SiCx layers have been characterized using Rutherford backscattering, IR spectrophotometry and scanning electron microscopy. The effects of high temperature exposure to oxygen have been examined using various oxidation test procedures including thermogravimetric analysis. SiCx layers capable of providing protection of underlying diamond for periods of several minutes at temperatures beyond 1000°C have been accomplished.

We report on p-SiC thin layer synthesis by carbon ion implantation at high temperature. Infra-red and RBS analysis were performed on samples implanted at temperatures ranging from 200 to 900°C and for carbon doses varying in the range 1017to2.1018 cm . RBS analysis does not reveal any diffusion or segregation of carbon up to 900°C. At this temperature we obtained the optimum Infra-red signature. The (3-SiC formation is shown to be a thermally activated process with an energy of 0.1 eV leading us to speculate that the diffusion of point defects could be the limiting factor of the process.

Penetration of alien atoms (Be, Ni) into Be, Al, Zr, Si and diamond was investigated under Ar+ ion bombardment of samples having thermally evaporated films of 30-50 nm. Sputtering was carried out using a wide energy spectrum beam of Ar+ ions of 9.4 keV to dose D=lxl0 -10 ion/cm2. Implanted atom distribution in the targets was measured by Rutherford backscattering spectrometry (RBS) of tT and He+ ions with energy of 1.6 MeV as well as secondary ion mass-spectrometry (SIMS).

During the bombardment, the penetration depth of Ar atoms increases with dose linearly. This depth is more than 3...20 times deeper than the projected range of bombarding ions and recoil atoms. This is a “deep action” effect.

The analysis shows that the experimental data for foreign atoms penetration depth are similar to the data calculated for atom migration through the interstitial site in a field of internal (lateral) compressive stresses created in the near-surface layer of the substrate as a result of implantation. Under these experimental conditions atom ratio r/rm (r¡ - radius of dopant, rm - radius target of substrate) can play a principal determining role.

Polycrystalline titanium samples were implanted with N+ ions at high fluences and at several energies. The aim was to obtain 4000 Â thick nitrided layers of constant nominal concentration equal to 20% ,30%, and 40%.

The results obtained by RBS showed a flat nitrogen distribution with depth and the measured concentrations were respectively 20%,31% and 38%.

X-ray grazing incidence diffraction indicated that, at 20%, a nitrogen solid solution is formed in the a-Ti matrix. At 31% the nitrogen solid solution is present besides a 5-TiN phase and at 38% only the 5-TiN phase remains.

From nanoindentation measurements, we derived the depth-related hardness and Young's modulus of the implanted samples. These values were compared to those found on titanium nitride layers obtained with other coating techniques.

A study has been made of the chemical composition and mechanical properties of Ti+-implanted Si3N4 surface layers. Implantation of 48Ti+ was performed with doses ranging from 10 to 1017 ions cm”2 at an energy of 150 keV, and at nearly room temperature. XPS was used to analyze the depth dependence of atomic fraction and chemical bonding states of Ti+-implanted layers. The near-surface hardness was measured by a Vickers hardness tester. The friction and wear properties were measured under unlubricated conditions at room temperature using a pin on disk-plane and a block on wheel-periphery configurations, in which the pin and wheel used were AISI1045 and ASTM Wl-9, respectively. Implanted Ti-atoms formed a gaussian distribution predicted by the range theory. At the average projected range, most of Ti-atoms existed as a metallic state and TiN bonding was also formed. Oxygen and carbon were found near the surface layers. In addition to the surface peak, O-atoms accumulated in front of the average projected range of Ti. Such O-atoms formed bonds of Si-oxides and Ti-oxides. Carbon existed as a graphitic state. With increasing a Ti dose, the near-surface hardness decreased, and the wear rate increased at the running-in stage having the high friction coefficient. The steady wear attributed to the stable friction coefficient appeared after the running-in stage, although such a stable stage was not observed for unimplanted Si3N4. The mechanism for the change in mechanical properties of Si3N4 induced by Ti+-implantation will be discussed in relation to XPS characteristics.

The behaviour of metallic impurities in Si is an issue of primary concern in advanced device processing. This paper addresses the annealing behaviour of Cu and Au in Si when nanocavities are present within the substrate as potential gettering and precipitation sites. In-situ, ‘hot’ Rutherford backscattering has been used to study metal accumulation to cavities at the annealing temperature. Transmission electron microscopy has been used to study the final microstructure of the Au-Si and Cu-Si system. A range of interesting phenomena have been observed, including very efficient transient gettering of both Cu and Au to cavities at the annealing temperature and precipitation of second phases at cavities. Dissolution of accumulated metal from defect bands into solution occurs for long-time annealing. This behaviour is discussed in terms of supersaturated solid solubility processes, diffusion, defect-trapping and precipitation of Cu and Au in Si.