Implantation Temperature Research Articles

Blistering/exfoliation kinetics of GaAs by hydrogen and helium implantations

The blistering and exfoliation kinetics of GaAs (100) wafer implanted by hydrogen and helium were studied. The influence of ion fluence, implantation and subsequent annealing temperatures on the blistering and/or exfoliation was studied by Rutherford Backscattering Spectroscopy (RBS), optical microscopy, high resolution X-ray diffraction (XRD) and cross-sectional transmission electron microscopy (XTEM). The optimum H + fluence for the GaAs blistering after annealing in the 160–350 °C temperature range was of 1–2 × 10 17 H +/cm 2 for implantation temperatures of 120–160 °C. An avalanche type exfoliation was found in the GaAs wafer implanted at room temperature with 100 keV helium ions at fluences of 2–5 × 10 16 He +/cm 2 after annealing in the 200–300 °C. In case of helium implantation, a notable dependency of the exfoliated depth on the fluence was found: XTEM analysis showing dislocation-bubble lines that serve as a fracture path for exfoliation.

Blistering kinetics of GaN by hydrogen implantation at high temperature

The hydrogen ion implantation condition for the ion-cut process in wurtzite-phase GaN and the associated mechanisms of surface blistering of GaN films were investigated. The hydrogen ions were implanted at 40 keV with fluences in the range of (1.5–5) × 10 17 H +/cm 2 over a wide temperature range (RT-450 °C), and at 60 keV at room temperature with fluences in the range of (3–5) × 10 17 H +/cm 2. The influences of the ion fluence, implant temperature and the post-implantation annealing conditions on blistering process were studied. Optical microscopy, field emission scanning electron microscopy (FE-SEM), high resolution X-ray diffraction (HRXRD), Rutherford backscattering spectrometry/channeling (RBS/C), and cross-sectional transmission electron microscopy (XTEM) were used to investigate splitting kinetics, and the optimum conditions for achieving blistering only after post-implantation annealing were determined for the GaN ion-cut process. The optimum fluence for the GaN blistering by hydrogen implantation and subsequent low temperature annealing (250–350 °C) was in the (2–3) × 10 17 H +/cm 2 range within the implantation temperature window of 150–300 °C with activation energies in the range of 1.0–1.6 eV depending on the implanted ion fluence and implant temperature.

Epitaxial 3C-SiC nanocrystal formation at the SiO2/Si interface after carbon implantation and subsequent annealing in CO atmosphere

3C-SiC nanocrystallites were epitaxially formed on a single crystalline Si surface covered by a 150nm thick SiO2 capping layer after low dose carbon implantation and subsequent high temperature annealing in CO atmosphere. Carbon implantation is used to introduce nucleation sites by forming silicon–carbon clusters at the SiO2/Si interface facilitating the growth of 3C-SiC nanocrystallites.

In Vivo Changes in Dental Implant Temperatures During Hot Beverage Intake: A Pilot Study

The aim of this study was to measure the increase in temperature in dental implants during the intake of hot beverages in vivo. Eight successfully osseointegrated implants in 7 subjects were examined. Each subject was asked to drink the same volume of hot beverage. While drinking, temperature changes were recorded via 3 embedded thermocouples placed (i) in the implant's internal space, (ii) at the implant-abutment interface, and (iii) at the abutment. All thermocouples were linked to a computer and analyzed with appropriate software. The maximum temperatures were 47.3 degrees C at the abutment, 45.6 degrees C at the implant's internal space, and 44.6 degrees C at the implant-abutment interface. A linear correlation was found between the temperatures measured (i) at the implant abutment and in the implant's internal space, and (ii) at the abutment and at the abutment-implant interface. Further clinical studies are required to determine whether the habitual consumption of hot food and beverages may be considered a risk factor in the success of implant-supported prostheses.

Temperature behavior of damage in sapphire implanted with light ions

In this study, we compare and discuss the defect behavior of sapphire single crystals implanted with different fluences (1×1016–1×1017cm−2) of carbon and nitrogen with 150keV. The implantation temperatures were RT, 500°C and 1000°C to study the influence of temperature on the defect structures. For all the ions the Rutherford backscattering-channeling (RBS-C) results indicate a surface region with low residual disorder in the Al-sublattice. Near the end of range the channeled spectrum almost reaches the random indicating a high damage level for fluences of 1×1017cm−2. The transmission electron microscopy (TEM) photographs show a layered contrast feature for the C implanted sample where a buried amorphous region is present. For the N implanted sample the Electron Energy Loss Spectroscopy (EELS) elemental mapping give evidence for the presence of a buried damage layer decorated with bubbles. Samples implanted at high temperatures (500°C and 1000°C) show a strong contrast fluctuation indicating a defective crystalline structure of sapphire.

Investigation of structure and composition of buried oxide layers formed by oxygen-ion implantation into silicon

Single-crystal ⟨ 1 1 1 ⟩ silicon samples were implanted at room temperature and at elevated temperature (325 °C) with oxygen (16O+) ions at 140 keV energy to fluence levels 1.0×1017, 2.5×1017 and 5.0×1017 cm−2 to synthesize buried layers using the SIMOX (separation by implanted oxygen) process. We have studied the process of buried oxide formation as a function of implantation temperature and fluence. The effects of fluence and implantation temperature on the structure and composition of the ion-beam-synthesized, buried silicon oxide layers were investigated by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) studies and Rutherford backscattering spectroscopy (RBS) measurements, respectively. The FTIR spectra of the implanted samples revealed a single broad absorption band in the wavenumber range 1250–750 cm−1, indicating the formation of silicon oxide. The integrated absorption band intensity was found to increase with increasing ion fluence. The absorption peak of the elevated-temperature-implanted sample was broader than that of the room-temperature-implanted sample. The structure of the ion-beam-synthesized oxide layers showed strong dependence on the fluence and implant temperature. The XRD studies reveal the synthesis of silicon oxide (SiO2) structure at all fluences. The RBS measurements show that the thickness of the buried oxide layer increases with an increase in the oxygen fluence. In general, however, the thickness of the top silicon layer was found to decrease with an increase in the ion fluence.

Microstructure of Cs-implanted zirconia: Role of temperature

The aim of this study was to identify experimentally the phase which includes cesium in yttria stabilized zirconia (YSZ). The solubility and retention of cesium in YSZ were studied at high temperature (HT). Cesium was ion implanted (at 300 keV) into YSZ at room temperature (RT), 750 °C, or 900 °C at fluences up to 5×1016 cm−2. The temperature dependence of the radiation-induced damage and of the cesium distribution in YSZ single crystals was investigated by Rutherford backscattering spectrometry and ion channeling. Transmission electron microscopy (TEM) studies were performed in order to determine the damage nature and search for a predicted ternary phase of cesium zirconate. Whatever the implantation temperature, the thickness of the damaged layer increases inwards with ion fluence. At RT, amorphization occurs, caused by the high Cs concentration (7at.%). In situ TEM during postannealing shows recrystallization of cubic zirconia after release of cesium. A high implantation temperature has a significant influence on the nature of radiation defects and on the retained Cs concentration. At HT, dislocation loops and voids are formed but no amorphization is observed whereas polygonization occurs at high fluence. The implanted cesium concentration reaches a saturation value of 1.5 at. % above which Cs can no longer be retained in the matrix and is then released at the surface. At that concentration, cesium forms a solid solution in YSZ; no other phase is formed, neither during irradiation nor after thermal annealing.

Temporal control of drug release from biodegradable polymer: Multicomponent diclofenac sodium releasing PLGA 80/20 rod

In our previous studies we have reported on the development of diclofenac sodium (DS) releasing rods. However, their drug release profiles were unsatisfactory. To enhance the drug release properties of the implant, we have developed a system whereby various elements can be combined into one implant. Melt extruded, self-reinforced (SR), and sterilized (S) DS-containing SR-PLGA 80/20 billets were combined to produce multicomponent implants with various compositions. These components were basically heat pressed together to form multicomponent rods. Drug release from single component and multicomponent rods was defined using a UV-Vis spectrophotometer. DS was released from individual components within 82-111 days and from multicomponent rods within 50-70 days. Thermal properties were analyzed using differential scanning calorimetry (DSC). The melting temperature (T(m)) of multicomponent implants was about 157 degrees C, change in heat fusion (DeltaH) was 13.3 J/g, and the glass transition temperature (T(g)) was 55.4 degrees C. Mechanical strength was measured for 2 weeks and it decreased from 55 to 15 MPa. In conclusion, by compression molding three components with different release rates it is possible to control the temporal release from multicomponent rods. Released DS concentrations were within range for 49-74 days depending on the fractions of individual components used.

Extended Defects Created by Light Ion Implantation in Ge

The effect of the implantation temperature in the range room temperature - 300oC has been studied in hydrogen and helium implanted germanium at high fluence and in the energy range of few tens of keV with either conventional implantation or plasma based ion implantation. The microstructure of the as-implanted Ge samples has been studied by Grazing Incidence Small-Angle X-ray Scattering and/or Transmission Electron Microscopy. For H-implanted Ge, small (001) and {111} platelets and {113} defects are nucleated at RT. With increasing the implantation temperature, microcracks, cavities and plate-like cavity clusters are created as well. The formation of these types of defects is ascribed to the interplay between dynamic and kinetic effects occurring during the implantation. As for He implanted Ge, a continuous cavity layer is formed whatever the implantation temperature in the range studied.

Electrical and topographical characterization of aluminum implanted layers in 4H silicon carbide

AbstractElectrical parameters and surface topography of aluminum (Al) implanted layers in 4H silicon carbide (SiC) are analyzed. The implantation is conducted for temperatures from room temperature up to 1000 °C. The impact of the post implantation annealing step on the Al implanted layers is investigated for two different annealing systems, a furnace system and a lamp system. The implanted layers are characterized in detail by atomic force microscopy and resistivity measurements. A model based on resistivity data is developed for the determination of activation and compensation and is discussed in order to get a better insight into the influence of the annealing step on the electrical parameters (e.g., hole mobility). In particular, the effect of elevated implantation temperatures on resistivity is identified. Additionally, the surface topography is examined regarding the annealing gas atmosphere. For that, a silicon carbide coated graphite crucible is used to achieve a silicon overpressure during annealing. The effectiveness of this crucible is identified by modeling. Measurements confirm the modeling results, that such a crucible prevents surface degradation only in the lamp system with heating rates of several 1000 K/min, and not in the furnace with heating rates in the range of some 10 K/min. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Amorphous Ge quantum dots embedded in SiO2 formed by low energy ion implantation

Under ultrahigh vacuum conditions, extremely small Ge nanodots embedded in SiO2, i.e., Ge–SiO2 quantum dot composites, have been formed by ion implantation of Ge+74 isotope into (0001) Z-cut quartz at a low kinetic energy of 9keV using varying implantation temperatures. Transmission electron microscopy (TEM) images and micro-Raman scattering show that amorphous Ge nanodots are formed at all temperatures. The formation of amorphous Ge nanodots is different from reported crystalline Ge nanodot formation by high energy ion implantation followed by a necessary high temperature annealing process. At room temperature, a confined spatial distribution of the amorphous Ge nanodots can be obtained. Ge inward diffusion was found to be significantly enhanced by a synergetic effect of high implantation temperature and preferential sputtering of surface oxygen, which induced a much wider and deeper Ge nanodot distribution at elevated implantation temperature. The bimodal size distribution that is often observed in high energy implantation was not observed in the present study. Cross-sectional TEM observation and the depth profile of Ge atoms in SiO2 obtained from x-ray photoelectron spectra revealed a critical Ge concentration for observable amorphous nanodot formation. The mechanism of formation of amorphous Ge nanodots and the change in spatial distribution with implantation temperature are discussed.

Effects of hydrogen implantation temperature on InP surface blistering

We have investigated the effects of hydrogen implantation temperature on the ion-cut process of InP by examining the correlation between surface blistering and the ion induced damage, hydrogen distribution, and strain. Using Rutherford backscattering spectrometry, elastic recoil detection, and x-ray diffraction, it was found that both the point defects induced by the hydrogen implantation and the in-plane compressive stress were necessary for hydrogen trapping and H-platelet nucleation and growth. The control of implantation temperature is crucial for creating sufficient defects and strain to induce surface blistering or layer exfoliation.

Resonant Rutherford backscattering spectrometry for carbon diffusion in silicon

300keV C+ ion implantation onto Si(100) wafers was carried out at temperatures of 400, 500, 550, 600, 650 and 700°C. Depth profile of C was determined by resonant Rutherford backscattering spectrometry (RRBS) measurements using 12C(α,α)12C resonant reaction with the α-particle energy of 4.27MeV. The concentration of the implanted carbon at the surface as a function of inverse of implantation temperature shows an Arrhenius behaviour. The activation energy for diffusion of carbon in Si was measured and found to be 0.434eV, which is smaller than the activation energy (0.88eV) for the C diffusion in Si in equilibrium condition. The possible mechanism of C diffusion in Si during irradiation conditions existing in our experiments where large concentration of vacancies and interstitials are produced is discussed and we find that the C diffusion during irradiation conditions could be due to the drag the carbon towards the surface by the vacancy flux.

Fe-implanted ZnO: Magnetic precipitates versus dilution

Nowadays ferromagnetism is often found in potential diluted magnetic semiconductor systems. However, many authors argue that the observed ferromagnetism stems from ferromagnetic precipitates or spinodal decomposition rather than from carrier-mediated magnetic impurities, as required for a diluted magnetic semiconductor. In the present article, we answer this question for Fe-implanted ZnO single crystals comprehensively. Different implantation fluences, temperatures, and post-implantation annealing temperatures have been chosen in order to evaluate the structural and magnetic properties over a wide range of parameters. Three different regimes with respect to Fe concentration and process temperature are found: (1) Disperse Fe2+ and Fe3+ at low Fe concentrations and low processing temperatures, (2) FeZn2O4 at very high processing temperatures, and (3) an intermediate regime with a coexistence of metallic Fe (Fe0) and ionic Fe (Fe2+ and Fe3+). Ferromagnetism is only observed in the latter two cases, where inverted spinel ZnFe2O4 and α-Fe nanocrystals are the origin of the observed ferromagnetic behavior, respectively. The ionic Fe in the last case could contribute to a carrier-mediated coupling. However, the separation between Fe ions is too large to couple ferromagnetically due to the lack of p-type carrier. For comparison, investigations of Fe-implanted epitaxial ZnO thin films are presented.

A comparison of the magnetic properties of proton- and iron-implanted graphite

In this work we have investigated the changes of the magnetic properties of highly oriented pyrolytic graphite samples after irradiation either with ~3×1014 protons or 3.5×1013 ... 3.5×1014 iron ions with energies in the MeV range. Our results show that iron and proton irradiations can produce similar paramagnetic contributions depending on the implantation temperature. However, only protons induce a ferromagnetic effect.

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.

Application of mass-separated focused ion beams in nano-technology

FIB applications like writing ion implantation, ion beam mixing or ion beam synthesis in the μm- or nm range often require ion species other than gallium. Therefore alloy liquid metal ion sources (LMIS) have to be developed and applied in FIB tools. The energy distribution of ions emitted from an alloy LMIS is one of the crucial parameters for the performance of a FIB column. Different source materials like AuGe, AuSi, AuGeSi, CoNd, ErNi, ErFeNiCr, MnGe, GaBi, GaBiLi, SnPb,… were investigated with respect to the energy spread of the different ion species as a function of emission current, ion mass and emitter temperature. Different alloy LMIS’s have been developed and used in the FZD – FIB system especially for writing implantation to fabricate sub-μm pattern without any lithographic steps. Co and various other ion species were applied to generate CoSi2 nano-structures, like dots and wires by ion beam synthesis or to manipulate the properties of magnetic films. Additionally, the possibility of varying the flux in the FIB by changing the pixel dwell-time can be used for the investigation of the radiation damage and dynamic annealing in Si, Ge and SiC at elevated implantation temperatures. Furthermore, a broad spectrum of ions was employed to study in a fast manner the sputtering process depending on temperature, angle of incidence and ion mass on a couple of target materials. These studies are important for the 3D-fabrication of various kinds of micro-tools by FIB milling.

Hydrogen blistering of silicon: Effect of implantation temperature, isotope dependence, and key role of dynamic annealing

Blistering of (001) Cz–Si crystals (>1Ωcm), by either protium (H) or deuterium (D) ions of 5keV energy, was studied as a function of the sample temperature during implantation in the range of 150–450K. It was found that the blistering dose thresholds decreased with temperature, and very dramatically so in the case of D ions, revealing new aspects of the giant isotope effect. An optimal implantation temperature for ion cutting was found around 100°C, where the required dose is reduced and the isotope effect is minimized. The results are interpreted in terms of models of the interaction of implanted hydrogen with radiation defects, and they show that dynamic annealing is incomparably more efficient in promoting blistering than purely thermal annealing.

Study on Chemical Behavior of Energetic Deuterium Implanted into Li2TiO3

Deuterium ion implantation and subsequent X-ray Photoelectron Spectroscopy (XPS) and Thermal Desorption Spectroscopy (TDS) experiments were performed with varying implantation temperatures to reveal chemical behavior of tritium produced in Li2TiO3. These experimental results showed that there were four deuterium trapping states; two of which were interacted with and without oxygen near the surface, and the other two were interacted with E’-center and with oxygen with the formation of O-D bond in the bulk. These trapping states of deuterium in the bulk were almost the same as those of tritium generated in thermal neutron-irradiated Li2TiO3. The total amount of deuterium retention in the bulk was almost constant until O-D bonds formed in the bulk were decomposed, indicating that tritium trapping could proceed under hot atom chemical reactions. It was concluded that E’-center could trap the implanted deuterium more frequently than oxygen with the formation of O-D bonds in the bulk. Annihilations of them due to oxygen recovery could increase the retention of D with the formation of O-D bonds, resulting in the almost constant deuterium retention ratio up to its decomposition temperature of 573 K.

Comparison of Defects Created by Plasma-Based Ion Implantation and Conventional Implantation of Hydrogen in Germanium

(001) n-type Ge has been implanted at given fluence and intermediate temperature with hydrogen ions using two processes: conventional in-line implantation and plasma based ion implantation. The as-created microstructure has been compared using transmission electron microscopy. In particular, it has been shown that the major differences observed are due to the implantation temperature, much higher during the PBII process. This suggests that plasma based ion implantation could be used for layer transfer in spite of a higher surface roughness observed after the PBII process.