Effect Of Implantation Temperature Research Articles

Study of the effect of implantation temperature on the migration behaviour of Xe implanted into glassy carbon.

The effect of implantation temperature on the migration behaviour of xenon (Xe) implanted into glassy carbon and the effect of annealing on radiation damage retained by ion implantation were investigated. Glassy carbon substrates were implanted with 320keV Xe+ to a fluence of 2×1016cm-2. The implantation process was performed at room temperature (RT) and 100°C Some of the as-implanted samples were isochronally annealed in vacuum at temperatures ranging from 300°C to 700°C in steps of 100°C for 10h. The as-implanted and annealed samples were characterized using Rutherford backscattering spectrometry (RBS) and Raman spectroscopy. The RT implanted depth profiles indicated that the migration of Xe towards the surface of glassy carbon was accompanied by a loss of Xe ions. The samples implanted at 100°C indicated no diffusion or loss of Xe after annealing at 300°C. However, annealing at temperatures ranging from 400°C to 700°C resulted in a slight shift in the Xe profile tail-end towards the bulk of glassy carbon. The diffusion coefficients (D) in the temperature range of 300°C-700°C for the RT and 100°C implanted samples, activation energies (Ea), and pre-exponential factors (Do), were extracted. The values of D ranged from (9.72±0.48)×10-21 to (1.87±0.09)×10-20m2/s with an activation energy of (6.25±0.31)×10-5eV for RT implanted samples, and the samples implanted at 100°C, D ranged from (3.85±0.19)×10-21 to (6.96±0.34)×10-20m2/s with activation energy of (4.10±0.02)×10-5eV. The Raman analysis revealed that implantation at the RT amorphised the glassy carbon structure while the samples implanted at 100°C showed mild damage compared to RT implantation. Annealing of the RT-implanted sample resulted in some recovery of the damaged region as a function of increasing annealing temperature.

Effects of implantation temperature and annealing on structural evolution and migration of Se into glassy carbon

The use of glassy carbon (GC) as a future nuclear waste storage material depends on its capability to retain all radioactive fission products found in spent nuclear fuels. Selenium (79Se) is found in trace amounts in uranium ores, spent, and reprocessed nuclear fuel. This work investigates the effects of implantation temperature and annealing on the structural evolution and migration of Se implanted GC. To achieve these objectives, 150 keV Se+ was implanted into GC samples separately at room temperature (RT) and 200 °C to a fluence of 1 × 1016 cm−2. Some of the as-implanted samples were annealed at 1000, 1100 and 1200 °C for 5h and characterised by transmission electron microscopy (TEM), Raman spectroscopy, and secondary ion mass spectrometry (SIMS). Both TEM and Raman spectroscopy showed that implantation caused defects in the GC structures, with more defects in the RT as-implanted sample. Annealing caused the healing of both sample types but retained some radiation damage. No migration of Se atoms was observed in the RT and 200 °C as-implanted samples. However, a different migration behaviour was seen after annealing the RT and 200 °C samples up to 1200 °C, attributed to the trapping and de-trapping of Se atoms in different amounts of defect induced by implantation.

Effects of Implant Temperature, Backside Contamination and Scribe Lines on Room Temperature Photoluminescence Measurements on Silicon

To investigate the effect of implantation temperature on the damage to a Si lattice, room temperature photoluminescence (PL) spectra were measured from highly-channeled MeV 11B+ implanted Si wafers with different implant temperatures (25 °C and 450 °C) after annealing at 950 °C for 3 min in N2. Small pieces from the wafers were used for PL characterization. The implanted Si wafer piece at the elevated temperature resulted in higher overall PL intensity under both excitation wavelengths suggesting lesser lattice damage than the Si wafer implanted at room temperature. Unexpectedly large PL intensity variations were observed from PL area mapping of both wafer pieces. In addition, strange behaviors of localized PL intensity variations, with opposite trends between 670 nm and 827 nm excitation PL measurements were observed near the scribe lines and sample number markings on the backside. The PL intensity was increased under 670 nm excitation while it was decreased under 827 nm excitation. Possible reasons for this strange behavior were discussed based on experimental results and analysis. PL measurement is verified to be very sensitive to the surface condition, interface, bulk and backside conditions of the Si. For reliable PL measurement, backside contamination and scratches, such as scribe lines, should be avoided.

Effects of Implantation Temperature and Annealing on the Microstructural Evolution of Hydrogen- and Helium-Implanted 6h-Sic

Effects of Implantation Temperature and Annealing on the Microstructural Evolution of Hydrogen- and Helium-Implanted 6h-Sic

Displacement damage dose and implantation temperature effects on the trapping and release of deuterium implanted into SiC

Radiation damage to flow channel insert (FCI) materials is an important issue for the concept of dual-coolant blanket development in future fusion devices. Silicon Carbide (SiC) is one of the most suitable materials for FCI. Because of the severe radiation environment and exposure to tritium during operation it is of fundamental importance to study hydrogen isotope trapping and release in these materials. Here the trapping, detrapping, and diffusion of deuterium implanted into SiC is studied in correlation with pre- and post-damage induced under different conditions. For this, SiC samples are pre-damaged with 50 keV Ne+ ions at different temperatures (20, 200, 450, 700 °C) to different damage doses (1, 3.6, 7 dpa). Next, deuterium is introduced into the samples at 450 °C by ion implantation at 7 keV. The implanted deuterium retained in the sample is analysed using secondary ion mass spectrometry (SIMS) and thermo-stimulated desorption (TSD) measurements. The results indicate that with increasing neon damage dose, the maximum deuterium desorption occurs at higher temperatures. In contrast, when increasing neon implantation temperature for a fixed dose, the maximum deuterium desorption release temperature decreases. It is interpreted that the neon bombardment produces thermally stable traps for hydrogen isotopes and the stability of this damage increases with neon pre-implantation dose. A decrease of the trapping of implanted deuterium is also observed to occur due to damage recovery by thermal annealing during pre-implantation at the higher temperatures. Finally, direct particle bombardment induced deuterium release is also observed.

Hydrogen accumulation in nanostructured as compared to the coarse-grained tungsten

We report on the influence of sample microstructure and of irradiation conditions on the H behaviour in Tungsten (W). For this purpose, commercial coarse grained (CGW) and nanostructured W (NW) samples were implanted with (i) H at room temperature (RT), (ii) sequentially with C and H at RT, and (iii) simultaneously (co-implanted) with C and H at RT. To study the possible effect of implantation temperature on H behaviour, a CGW sample and a NW sample were sequentially implanted with C at RT and with H at 673K. The H and C implantation fluence was 5×1020m−2 and the implantation energies were 160keV for H and 650keV for C which are above the displacement damage threshold. Scanning electron microscopy images show that nanostructured samples consist of columns with an average diameter of about 100nm. These nanocolumns are stable under the studied implantations conditions. Moreover, surface modification is absent in all studied samples. X-ray diffraction data illustrate that all samples are mono-phase (α-W phase) and that none of the implantations led to the appearance of secondary phases. Resonant nuclear reaction analysis data show that the H retention in NW samples is larger than in CGW and that synergistic effect has a significant influence on the H retention in CGW samples but not in NW samples.

Effect of implantation temperature on exfoliation of H2+-implanted Si

The effect of implantation temperature of crystalline silicon implanted with hydrogen on exfoliation was investigated. The samples were analyzed by Raman scattering spectroscopy, optical microscopy and transmission electron microscopy. Our experiment shows that the concentrations of implantation-induced defects and hydrogen decrease with the implantation temperature. Compared to the implantation at 573 K and 773 K, (100) platelets are preferentially nucleated when the sample was implanted at room temperature (RT), while {111} platelets are preferentially nucleated for the elevated temperature implantation. After annealing at 773 K, blisters and exfoliation occur for the sample implanted at RT but not the sample implanted at 573 K. Microstructure shows a microcrack in the damaged layer for the sample implanted at RT. After annealing at 973 K, blisters and exfoliation occur for the samples implanted at RT, 573 K and 773 K. The exfoliation mean size increases, but the exfoliation density decreases with the implantation temperature. Microstructure shows a microcrack in the damaged layer for the samples implanted at RT, 573 K and 773 K. The depth of the microcrack is related to the implantation temperature. The effects of implantation temperature on dislocation loops, platelet nucleation and growth were investigated.

Effect of implantation temperature on the H-induced microstructural damage in AlN

A detailed physical investigation of the H-induced microstructural damage in (0001) AlN epitaxial layers at various implantation temperatures is presented. Cross-sectional transmission electron microscopy revealed that in the case of samples implanted at 300°C, extended defects (nanocracks) were formed only within ∼50nm region situated below the H-concentration peak in the damage band of width ∼280nm compared with lower implantation temperatures. This implantation temperature-dependent behavior of the microstructural damage decides the morphology of the top buckled surface. Various favorable conditions for the buckling of H-implanted surface in the form of large area exfoliation are proposed based on the present study.

Implantation Temperature Effects on the Nanoscale Optical Pattern Fabrication in a-SiC:H Films by Ga+Focused Ion Beams

This work has been supported by the European Community as an Integrating Activity “Support of Public and Industrial Research using Ion Beam Technology (SPIRIT)” under EC contract No. 227012. The support of EC funded project BG051PO001/3.3.-05.001 for this publication is gratefully acknowledged. The Marie Curie Fellowship for T. Tsvetkova was also supported by the European Community under the contract PIEF-GA-2009-251845. The help of D. Dimova-Malinovska and O. Angelov with the samples preparation and useful discussions is also gratefully acknowledged.

Effects of implantation temperature and thermal annealing on the Ga+ ion beam induced optical contrast formation in a-SiC:H

The effects of implantation temperature and post-implantation thermal annealing on the Ga+ ion beam induced optical contrast formation in hydrogenated silicon–carbon alloy films have been studied. As a result of the implantation a well-expressed “darkening” effect (i.e. absorption edge shift to the longer-wavelength/lower-photon-energy region) has been registered. It is accompanied by a remarkable increase of the absorption coefficient up to 2 orders of magnitude in the measured photon energy range (1.5–3.1eV). The optical contrast thus obtained (between implanted and unimplanted regions of the film material) has been made use of in the form of optical pattern formation by computer-operated Ga+-focused ion beam. Possible applications of this effect in the area of submicron lithography and high-density optical data storage have been suggested with regard to the most widely spread focused micro-beam systems based on Ga+ liquid metal ion sources. The fact that Ga has a very low melting point (Tm=29.8°C) and an unusual feature of volume contraction on melting are factors which favour Ga incorporation upon ion-implantation as dispersed clusters, or small nanoparticles. It has been previously noted that Ga precipitation into nanoparticles can vary dramatically (in terms of particle size) with Ga concentration and small changes in surface implant temperature, thus affecting the optical properties of the target. The precise role of implantation temperature effects, i.e. the target temperature during Ga+ ion irradiation, on the optical contrast obtainable, has been therefore a key part of this study. Appropriate post-implantation annealing treatments were also studied, since these are expected to offer further benefits in reducing the required ion dose and enhancing contrast, thus increasing the cost-effectiveness of the bit-writing method.

Thermal effects on the Ga+ ion beam induced structural modification of a-SiC:H

The effects of implantation temperature and post-implantation thermal annealing on the Ga+ ion beam induced optical contrast formation in hydrogenated silicon-carbon alloy (a-SiC:H) films and underlying structural modifications have been studied. The optical contrast formed (between implanted and unimplanted regions of the film material) has been made use of in the form of optical pattern formation by computer-operated Ga+-focused ion beam. Possible applications of this effect in the area of submicron lithography and high-density optical data storage have been suggested with regard to the most widely spread focused micro-beam systems based on Ga+ liquid metal ion sources. The implanted samples were structurally analysed using vibrational spectroscopies, like Raman and infra-red (IR) spectroscopy, to define optimum implantation conditions. The precise role of implantation temperature effects, i.e. the target temperature during Ga+ ion irradiation, on the structural modification obtainable has been therefore a key part of this study. Appropriate post-implantation annealing treatments were also studied, since these are expected to offer further benefits in reducing the required ion dose and enhancing the optical contrast, thus increasing the cost-effectiveness of the method.

Effect of implantation temperature on the blistering behavior of hydrogen implanted GaN

GaN epitaxial layers were implanted by 100 keV H+ ions at different implantation temperatures (LN2, RT and 300 °C) with a fluence of 2.5×1017 cm−2. The implanted samples were characterized using Nomarski optical microscopy, AFM, XRD, and TEM. Topographical investigations of the implanted surface revealed the formation of surface blistering in the as-implanted samples at 300 °C and after annealing at higher temperature for the implantation at LN2 and RT. The physical dimensions of the surface blisters/craters were dependent on the implantation temperature. XRD showed the dependence of damage-induced stress on the implantation temperature with higher stress for the implantation at 300 °C. TEM investigations revealed the formation of a damage band in all the cases. The damage band was filled with large area microcracks for the implantation at 300 °C, which were responsible for the as-implanted surface blistering.

Correlation between implantation defects and dopants in Fe-implanted SiC

SiC single crystals were implanted with Fe ions and the effects of implantation temperature, Fe concentration, and subsequent swift heavy ion irradiation on both dopant and damage depth distributions were evaluated by using RBS and channelling techniques. It is found that an increase of the implantation temperature above the threshold temperature for amorphization can lead to the formation of a broad layer (∼50 nm) containing a large concentration of implanted Fe atoms (∼2 at.%) but almost free of implantation defects. This particular configuration is likely due to dynamic annealing during implantation combined with defect annihilation at the surface. It is only observed when the implanted species concentration does not exceed a critical value (which lies between 2 and 5 at.% in the present system). Post-implantation swift heavy ion irradiation leads to a further decrease of the damage level, while the Fe distribution is not affected. The Fe substitutional fraction has been evaluated in the different tested conditions. A maximum value of ∼50% is found when implantation is performed at the temperature above that required to prevent amorphization (470 K in the present system). Swift-heavy ion irradiation seems to induce Fe atoms relocation at substitutional positions.

Effects of Implantation Temperature on Sheet and Contact Resistance of Heavily Al Implanted 4H-SiC

Effects of implantation temperature on electrical properties of heavily-Al-doped 4H-SiC layer formed with Al implantation have been investigated. To form the p++ 4H-SiC with the original 4H-stacking structure, the implantation temperature above 175 °C is needed. A decrease in the implantation temperature below 250 °C leads to an increase in the NA-ND. It is suggested that an increase in the density of vacancies with a decrease in the implantation temperature promotes the Al substitution to lattice sites during activation annealing. The lower-temperature implantation also causes a decrease in activation energy for the p-type electrical conduction and a decrease in p-type ohmic contact resistivity. We presume that the increase in the Al acceptors at low-implantation temperatures gives expansion of the impurity bands and formation of valence band tail-states, causing the decrease in the impurity binding energy. The properties obtained with the lower-temperature implantation are desirable for practical applications especially at low temperatures.

Embedment of HA into Superplastic Ti-6Al-4V: Effects of Implantation Temperature

In this research, we present a method for the embedment of hydroxyapatite (HA) into superplastic Ti6Al4V where the elements of HA and Ti6Al4V diffuse into each other to form a high quality implanted layer. The implantation process into superplastic titanium alloy was divided to two steps; first, the superplastic forming of Ti6Al4V was carried out using high-temperature compression test machine. In the second step, HA was embedded into superplastic Ti6Al4V by using a special designed clamp with an initial compressive load at high temperatures. The EDX and Line Scanning analyses indicate that the resulted film is composed of elements of HA and titanium alloy and due to the diffusion of HA and Ti6Al4V elements into each other, a good embedment is achieved. The elemental diffusion of HA and Ti6Al4V increases by increasing the temperature of the implantation process therefore the thickness of the implanted layer and the hardness of the embedded surface increase with the temperature.

Effect of Elevated Implant Temperature on Amorphization and Activation in As-implanted Silicon-on-insulator Layers

ABSTRACTThe ion implantation steps used in fabricating field effect transistors in ultrathin (6 to 30 nm) silicon-on-insulator (UTSOI) substrates present many challenges. Deep source/drain (S/D) implants in UTSOI layers are a particular concern, since it can be difficult to implant the desired dose without amorphizing the entire SOI thickness. In a first study, we investigated the effect of implant temperature (20 to 300 °C) on the sheet resistance (Rs) of 28 nm thick SOI layers implanted with As+ at an energy of 50 keV and a dose of 3 × 1015 /cm2, and found Rs values after activation sharply lower for samples implanted at the highest temperature. In a second study, on 8 nm thick SOI layers implanted with As+ at an energy of 0.75 keV and doses in the range 0.5 to 2 × 1015/cm2, the benefits of the elevated implantation temperature were less clear. Explanations for these effects, supported by microscopy, medium energy ion scattering (MEIS), and optical reflectance data, will be discussed.

Effects of implantation temperature and volume flow rate ratio of nitrogen and hydrogen on nitrogen concentration distribution, mechanical properties, fatigue life, fracture toughness, and tribological behavior of plasma-nitrided P20, 718 and 420 steels

In the present study, three steel materials, AISI P20 DEM NO.3, ASSAB 718 and AISI 420, were selected as the mold substrate materials in plastic injection forming. The plasma immersion ion implantation (PIII) system with an electron cyclotron resonance microwave source was applied to prepare the specimens by varying the implantation temperature (400 °C, 460 °C and 520 °C) and the volume flow rate ratio (4:1, 1:1 and 1:3) of nitrogen to hydrogen in the gas mixture (N 2:H 2). For the specimens with the same substrate material, the mean hardness was either invariant to or lowered by increase in the total penetration depth of nitrogen. The hardness was lowered by increasing the distance of the peak position of nitrogen concentration from the implantation surface. Both the fracture toughness and the fatigue life of a specimen at the nitrided layer were elevated by increasing the implantation temperature. The most significant increase in each of these two mechanical properties due to the temperature increase gives rise in the P20 specimens. Varying the N 2:H 2 ratio shows a fatigue life sequence of (FL) 4:1 > (FL) 1:3 ≥ (FL) 1:1 for all three substrate materials. X-ray diffraction (XRD) was applied to determine the phase structures at the nitrided layer which was formed by changing either the implantation temperature or the N 2:H 2 ratio. The (α-Fe + CrN) phase in the nitrided later can elevate the fatigue life and fracture toughness of the specimen. However, the increase in the hardness is due to the combined effect of all main phases formed in the nitrided later. The scratch wear resistance of a specimen with ion implantations is significantly enhanced compared with that exhibited in the “pure” specimen (without nitrided layer). However, most of the specimens with ion implantations showed severer adhesive wear than corresponding “pure” specimens.

Study on Properties of M50 Steel Implanted With Nitrogen by Plasma-Based Ion Implantation at Elevated Temperatures

M50 steel was implanted with nitrogen at elevated temperatures ranging from 260 degC to 420 degC using plasma-based ion implantation. The effect of implantation temperature on surface microstructure, hardness, and wear resistance was investigated. It is observed that nitrogen penetrates very deeply from the surface as a result of implantation and thermal diffusion at elevated temperatures. The amount of nitrides and their distribution depth as well as the hardness and the wear resistance in the surface layer increase with the processing temperature. As the implantation temperature increases, the wear mechanism changes from adhesive wear to abrasive wear

High-fluence Si-implanted diamond: Optimum implantation temperature for SiC formation

In this paper the authors investigate the effect of implantation temperature on the structural properties of diamond implanted with high fluences of Si between 5.3×1017Sicm−2 and 1×1018Sicm−2. In order to reduce radiation-induced damage and to enhance SiC formation the implantations were performed at elevated temperatures in the range from 900to1200°C. Subsequently, all samples were annealed for 10min at 1500°C in a rf-heated furnace. X-ray diffraction revealed the formation of cubic SiC nanocrystallites in a buried layer inside the implanted diamond. The implantation-induced damage was assessed by analyzing graphitization of the surface-near layer using Raman spectroscopy. With increasing Si fluence the implantation-induced damage rises and the nearly perfect alignment of the formed SiC crystallites within the host diamond lattice deteriorates. However, raising the implantation temperature from 900to1000°C reduces the damage in the diamond and increases the amount, size, and epitaxial alignment of the crystalline SiC precipitates. Further increase of the implantation temperature gives no improvement in the quality of the SiC-rich layer. Instead, the damaged diamond converts into graphite and the formation of SiC crystallites is obstructed.

Effect of Implantation Temperature on Redistribution of Al in SiC during Annealing

Effect of Implantation Temperature on Redistribution of Al in SiC during Annealing