TRIM Simulation Research Articles

Remote hydrogen plasma treatment (RHPT) of ion implanted CVD diamond

Defects formation of chemical vapor deposition (CVD) diamond on 4He 2+ irradiation and after remote hydrogen plasma treatment (RHPT) were investigated by cathodoluminescence (CL). For the RHPT, the substrate was kept away from direct plasma ball while it was treated for 0.5 to 2 h. As calculated in the TRIM simulation, the light elements of 4He 2+ can be penetrated into the diamond bulk structure at 3–4 μm depth. The effects of the implantation region were observed when 5–20 keV electron energy (understanding of 0.3–4.0 μm) of CL measurement was irradiated to diamond at a temperature of 80 K. After the RHPT, rehybridization of irradiation damaged diamond was studied. The intensity of 5RL center (intrinsic defect of C) was diminished. The 2.16 eV center (N-V center) occurring usually by annealing could not be seen after RHPT. It seemed that the diamond was not influenced to reconvert its structure by high temperature annealing. The diamond was rehybridized by hydrogen radicals without etching by the RHPT.

Refractive index reconstruction of graded-index buried channel waveguides from their mode intensities

The refractive index distribution has been determined for a number of graded-index, single-mode, buried channel waveguides, formed by irradiation with a high energy focused ion beam. The refractive index has been calculated from the waveguide's mode field intensity at a wavelength of 670 nm, via an inversion of the scalar wave equation. Waveguides with doses in the range 0.7/spl times/10/sup 15/-4.1/spl times/10/sup 15/ ions/spl middot/cm/sup -2/ exhibited a peak refractive index change increasing linearly with ion dose, in the range 0.01-0.08%, and the results are consistent with profiles derived from TRIM simulations.

Source/Drain Ion Implantation into Ultra-Thin-Single-Crystalline-Silicon-Layer of Separation by IMplanted OXygen (SIMOX) Wafers

Problems associated with ion implantation into ultra-thin-film SIMOX (Separation by IMplanted OXygen) of SOI (silicon on insulator) structures are discussed. We realized n-type source/drain region with lower resistance by P+ ion implantation. To decrease the resistance of the implanted layer, the amorphized high-dose layer must be recrystallized by annealing. We show that the possibility of recrystallization can be predicted by TRIM simulation. Moreover, it was found that excess phosphorus above the solid solubility segregates in the Si/SiO2 interface.

The influence of ion energy on the wear behaviour of titanium-implanted silicon nitride ceramics

The effects of the titanium implantation depth on the wear behaviour of two different silicon-nitride-based engineering ceramics with different binding phase compositions are investigated. Implantation energies were 150, 400, 1000 and 2000 keV, corresponding to projected implantation ranges from about 100 nm to 1100 nm as predicted by trim simulations. The fluence was 10 17 Ti + ions cm −2 in all cases. X-ray diffraction was used in order to determine the degree of amorphization of the near-surface region due to implantation. No titanium-containing phases have been detected. Wear tests were performed at room temperature with an oscillating ball-on-disc type tribometer. The wear tracks were subsequently investigated using surface profilometry and energy-dispersive X-ray spectroscopy. The wear is reduced for all implanted samples. The influence of the implantation depth on the wear behaviour and the relationship between the friction coefficient and the observed wear are discussed.

Stopping-powers and straggling of 15N ions for nuclear reaction analysis at 6.385 MeV

Stopping-powers and straggling has been measured for 15N incident ions at 6.4 MeV using the well known 1H( 15N,αγ) 12C resonant nuclear reaction at 6.385 MeV. Samples have been prepared using electron beam evaporation of various elements on H terminated silicon substrates under UHV conditions with high layer quality. The H monolayer remains stable at the silicon substrate during evaporation and ion irradiation. The layer thicknesses were ranging from 500 to 2000 Å. At this thickness range the energy straggling is between 15 and 40 keV (σ) and is the main contribution to the measured width of the H profile. Surface roughness, interface quality and Doppler broadening are negligible. The measured H profiles were fitted with a Gaussian normal distribution function. In the case of target materials, as e.g. Nb, which incorporate H easily, the layers were H charged and an integrated Gauss function was used for fitting. The stopping-powers and straggling were compared with ZBL data for electronic stopping, Bohr straggling and TRIM simulations for nuclear stopping and straggling and with former experimental data obtained with same method. The data for stopping-power and straggling showed remarkable differences to former measurements.

Growth, microstructure, and strain relaxation in low-temperature epitaxial Si1−xGex alloys deposited on Si(001) from hyperthermal beams

Epitaxial Si1−xGex(001) alloy films, with 0.15≤x≤0.30, were grown on Si(001) at temperatures Ts ranging from 300 to 550 °C using hyperthermal Si (average energy 〈ESi〉≂18 eV) and Ge (〈EGe〉≂15 eV) beams. The deposition rate was 0.1 nm s−1 and film thicknesses ranged from 30 nm to 0.8 μm. The energetic Si and Ge beams are generated by bombarding Si and Ge targets with 1 keV Kr+ ions from double-grid, multiaperture, broad ion-beam sources in a system geometry established based upon TRIM simulations of energy-dependent angular distributions of sputtered and backscattered particles. A combination of high-resolution plan-view and cross-sectional transmission electron microscopy, high-resolution x-ray diffraction, Rutherford backscattering spectroscopy, channeling, and axial angular-yield profiles demonstrated that the films are of extremely high crystalline quality. Critical layer thicknesses hc for strain relaxation in these alloys were found to increase rapidly with decreasing growth temperature. For Si0.70Ge0.30, hc ranged from 35 nm at Ts=550 °C to 650 nm at 350 °C compared to an equilibrium value of ≂8 nm. At even lower growth temperatures, hc becomes larger than critical epitaxial layer thicknesses, ≳1 μm at 300 °C. In addition, atomic force microscopy studies showed that strain-induced roughening, which occurs at elevated growth temperatures, is strongly suppressed at Ts between 300 and 400 °C with no indication of kinetic roughening.

Study of Lowenergy Atomic Mixing by Means of Auger Depth Profiling, XTEM and TRIM Simulation on GeSi Multilayer System

Study of Lowenergy Atomic Mixing by Means of Auger Depth Profiling, XTEM and TRIM Simulation on GeSi Multilayer System

Study of Low-energy Atomic Mixing by Means of Auger Depth Profiling, XTEM and TRIM Simulation on Ge/Si Multilayer System

Low-energy atomic mixing is experimentally studied on a Ge/Si amorphous multilayer system by means of Auger depth profiling and XTEM. The ion etching was performed by using Ar ions of energy 500 eV (XTEM) and 618 eV (Auger) and angle of incidence >84° and the specimen was rotated during sputtering. Applying these conditions it is believed that the interface broadening occurs mainly because of atomic mixing because the surface roughening is negligible. The Auger depth profile was carried out on a specimen containing Ge/Si strips parallel to the surface. The extent of the atomic mixing was determined by comparing the depth profile to profiles provided by dynamic TRIM simulation. For ion milling another geometry was used ; the Ge/Si strips were perpendicular to the surface. A very thin (2 nm) TEM specimen was prepared and the thickness of the completely mixed region could be directly estimated from the TEM image : 1 nm at 500 eV ion energy and 85° angle of incidence. The TEM image also shows that the atomic mixed region is asymmetric.

CLUSTER ION BOMBARDMENT-INDUCED SURFACE DAMAGE OF Si

Surface damage of single-crystalline Si caused by irradiation with Ar-ion cluster beams of different energies has been studied in comparison with that caused by Ar-monomer ion beams. The defected layers have been characterized by RBS channeling, XTEM, and ellipsometry. The experimental results are interpreted on the basis of TRIM and molecular dynamics simulations of the interaction processes with the target. It is found that cluster irradiation damages only a very thin near-surface layer which has a smooth interface to the undamaged substrate. Cluster-ion bombardment forms an oxide layer on the surface by the activation of adsorbed O atoms and substrate atoms.

Particle dependence of the gallium vacancy production in irradiated n-type gallium arsenide

The relative introduction rate of the gallium vacancy in n-type GaAs irradiated with /sup 60/Co /spl gamma/ rays, 7 MeV electrons, fusion (14 MeV) and fission (1 MeV) neutrons, protons (0.6 to 200 MeV), deuterons (1 to 10 MeV), /spl alpha/ particles (2.5 to 10 MeV), lithium (5 to 20 MeV) and oxygen ions (10 to 30 MeV) has been determined. Effects of annealing are reported. The measured introduction rates obtained with proton irradiation for energies up to 10 MeV, and for the heavy ions agree reasonably well with Rutherford scattering, NIEL calculations and the TRIM simulation. The results for electron irradiation also agree with the corresponding NIEL calculations.

Silicon implant annealing kinetics in GaAs

A detailed study of the activation kinetics of silicon implanted GaAs has been carried out for implantation energies ranging from 100 keV to 2 MeV, with ion fluences chosen to give silicon concentrations in the useful range of between 10 17 and 10 19 Si cm −3 for all the implant energies studied. Anneal times have been varied over three orders of magnitude to give information relating to both RTA and furnace anneals with the temperatures being varied from 700 to 1150°C. The effect of compositional changes in the dielectric encapsulant has also been studied and shown to be a major variable in the activation mechanism. SIMS analysis has been compared with TRIM simulations to give information on the atomic concentration of the implanted silicon. Following annealing, differential Hall effect measurements have been used to obtain electron concentration and mobility profiles for comparison with the atomic concentration and implant induced disorder profiles. In this paper, the role of implantation damage, vacancy distribution and implant dopant concentration is discussed in conjunction with a model for the activation of silicon implants in GaAs.

Damage threshold for ion-beam induced graphitization of diamond

The critical dose for graphitization of diamond as a result of ion implantation induced damage (boron and arsenic) and subsequent thermal annealing is determined by combining secondary ion mass spectroscopy measurements, chemical etching of the graphitized layer, and TRIM simulations. Li ions are implanted as a deep marker to accurately determine the position of the graphite/diamond interface. The damage density threshold, beyond which graphitization occurs upon annealing, is found to be 1022 vacancies/cm3. This value is checked against published data and is shown to be of general nature, independent of ion species or implantation energy.

Fabrication, characterization and electro-optic performances of proton-implanted waveguides in LiNbO 3

Planar optical waveguides were built up by proton implantation (ion of H +) in single crystal of lithium niobate. The waveguide properties are investigated by a prism coupling technique (M-lines spectroscopy). The reconstructed refractive index variation profile obtained with the inverse WKB method, is compared with the ion concentration profile as determined by TRIM simulation program. The electro-optic coefficient, r 13, has been measured through the change in coupling angle of the modes excitation under an applied electric field.

Experiments and TRIM simulations on sputtering of well defined amorphous metal alloys containing impurities

Sputtering yields of amorphous metal alloys of FeCoSiB are measured and compared with numerical simulations based on the TRIM.SP code. The amorphous samples are prepared under well controlled cooling condition during quenching, resulting in well defined values of the density and bonding energy. The Ar ion beam sputtering is carried out by using a Kaufman-type ion source with an ion energy and ion current density of 1.0 keV and 0.6 mA/cm 2. From the eroded depth, the sputtering yield is determined as function of atomic density and bonding energy, showing remarkable dependence on both these quantities. The change of measured sputtering yield is explained by the simulation.

Measurement of the distribution of damage in ion implanted GaAs by differential reflectance spectroscopy

The distribution of damage in Si and He implanted GaAs has been studied using differential reflectance (DR) spectroscopy. This novel and relatively simple optical technique has high sensitivity and allows the measurement of damage distributions in a low dose range which is difficult to access by other techniques (1 × 10 10−3 × 10 14 cm −2). The effect of crystal orientation ((100), (110) and (111) directions) on the damage profiles has also been measured. The measured damage profiles, obtained by successively etching the sample and measuring the DR signal, have been compared with TRIM simulations. The magnitude and shape of the damage profiles were found to be very sensitive to crystal orientation.

Microstructural changes due to ion irradiation in β-CuZnAl alloys

The {beta}-phase CuZnAl alloys undergo martensitic transformations to several close-packed structures, depending on the alloy composition. In order to study the effects of higher doses of irradiation on the phase stability in these alloys, ion irradiation experiments are now being carried out. In this work, results on microstructural changes after light and heavy ion irradiation in the {beta} phase of CuZnAl alloys followed by Transmission Electron Microscopy are reported. Single crystals of composition Cu-22.7at.%Zn-12.7at.%Al were used. At this composition, the B2 ordering temperature is about 810K, the L2{sub 1} ordering temperature is about 530K and the martensitic transformation temperature is below liquid nitrogen temperature. At room temperature, the alloy has then an L2{sub 1} long-range-ordered structure. Disks of 3mm diameter were prepared by spark erosion. In most experiments the orientation of the foil was close to (110). The samples were irradiated on one side and then back-polished from the other side to perforation, for observation in TEM. Irradiations were carried out with 300 keV Cu{sup +} ions with a flux of 5 {times} 10{sup 12} ions/cm{sup 2}s and 300 keV He{sup +} ions with a flux of 5 {times} 10{sup 13} ions/cm{sup 2}s. The dose rates, calculated using cross sectionsmore » obtained from TRIM simulations, with an average threshold energy of 25 eV, were 10{sup {minus} 2} dpa/s. for the Cu{sup +} and He{sup +} irradiations respectively. The irradiation temperature for the former was about 316K. For the later, a cooling holder was used to keep the temperature between 283K and 289K during irradiation. Before irradiation, the samples were annealed at 1,120K for 20 minutes and cooled in air to room temperature.« less

2 MeV As + implantation in InAs

High energy ion implantation of 2 MeV As + ions into 〈100〉 InAs was investigated using Rutherford backscattering spectrometry with 2 MeV He + ions. The ion fluence N 1 varied over a wide range between 2 × 10 12 cm −2 and 5 × 10 16 cm −2. The relative defect concentration n pd( z), calculated from the backscattering spectra with the help of the computer code DICADA2, is compared to the distribution of the electronic and the nuclear energy density obtained from TRIM simulations. It is found that the defect mobility and the defect annealing during room temperature implantation are strongly influenced by the total energy density deposited into electronic processes. A similar behaviour is found for GaAs but not for InP. We believe that in the arsenides the energy deposition into electronic processes reduces the efficiency of the nuclear energy deposition for producing stable defects.

Ex-situ XPS-investigation of the interface between PE-CVD SiO2 and wet chemically etched MO-CVD epitaxial layers of In0.53Ga0.47As

The As rich SiO2/In0.53Ga0.47As interface which is produced by wet chemical etching before SiO2 deposition to improve the electronic properties of the interface has been studied. SiO2-layers of about 10 to 20 nm thickness have been deposited in a plasma enhanced chemical vapour deposition (PECVD) reactor and then thinned down to about 4 to 3 nm by 1.5 keV Ar ion beam bombardment at grazing incidence (85°) in the XPS analysis chamber. The photoelectron spectra show that an additional broadening of the In and As lines due to a possible ion beam damage can be neglected in case of a qualitative interpretation of the interface spectra. Moreover, TRIM simulations of the collision cascade reveal low damage production in the SiO2/In0.53Ga0.47As interface region. Therefore such ex-situ XPS experiments allow a supervision of the interface chemistry after the fabrication process and an optimisation of the technology with regard to the etching solution and deposition conditions. The conservation or removal of the elemental arsenic and the oxidation of the semiconductor due to the SiO2 deposition are well reflected in the photoelectron spectra.

Backscattering and electron microscopy study of mega-electron volt gold implantation into silicon

Rutherford backscattering spectrometry and cross-section transmission electron microscopy have been used to study implantation of MeV Au+ ions into silicon. Measured range (Rp) and straggle (ΔRp) values for MeV Au+ implanted silicon are found to be consistently larger than values predicted by trim simulations. The magnitude of the discrepancies are such that the differences cannot be attributed to implantation effects alone. We conclude that the trim computer program does not accurately predict Rp and ΔRp values for MeV Au+ implantation into crystalline Si. Experimental results show that for low-current low-energy implants a single Gaussian Au profile is achieved. Low-power implants produce a single band of damage consisting of simple point defects. High-current high-energy implants lead to the creation of more complex defect structures such as dislocation networks; these arise as a result of dynamic beam recrystallization. Multiple layers of precipitation are observed in silicon implanted with MeV Au+ ions in those samples where dynamic recrystallization occurred. Precipitation occurs as a result of the local Au concentration exceeding the solid-solubility during beam-induced recrystallization. Different mechanisms operate in conjunction to cause anomalous Au motion which results in formation of multiple precipitate layers. A first mechanism has the implanted Au segregating into a densely defected region; when the concentration exceeds the local solid solubility Au precipitates out of the matrix. A second mechanism has motion of Au along dislocations in a network; the diffusing Au reaches a dislocation-node where it exceeds the local threshold for precipitation and the Au therefore precipitates. Enhanced Au diffusion is dependent upon the magnitude of dynamic recrystallization occurring during the implantation.

Oxygen diffusion in ion-implanted layer of Nb-doped SrTiO 3

Oxygen diffusion phenomena were investigated on Nb-doped SrTiO 3 crystals after Ar or F ion implantation. SIMS measurements indicated that oxygen diffusion profiles consisted of high and low diffusivity regions; the profiles were analyzed by a two-layer model and diffusion coefficients were evaluated. According to TEM observation, there existed three layers in the implanted region whose boundaries were in good agreement with the positions analyzed. A large number of dislocations were produced by the ion implantation, which disappeared upon thermal annealing. The distribution of oxygen vacancies was determined from the diffusion coefficients, and compared with the results of TRIM simulations.