共查询到20条相似文献,搜索用时 15 毫秒
1.
J.X. Xu X.H. Xiao F. Ren C.Z. Jiang 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2010,268(17-18):2702-2705
(0 0 0 1) α-Al2O3 single crystals (sapphire) were implanted with Zn ions of 60 keV at a fluence of 1 × 1017 ions/cm2. Transmission electron microscopy and optical absorption spectroscopy studies show the formation of ZnO nanoparticles in the sapphire substrate after the implanted sample was annealed at 700 °C in oxygen ambient. The photoluminescence spectrum of the annealed sample indicates the formation of ZnO nanoparticles with perfect lattice structure. The selected-area electron diffraction pattern proves that the ZnO nanoparticles have the (0 0 0 2) orientation which follows the orientation of Al2O3 substrate. The result shows that the crystallographic orientation of nanoparticles obtained through ion implantation is defined by the substrate. 相似文献
2.
Tomoko Yoshida Shunsuke Muto Leny Yuliati Hisao Yoshida Yasuhiro Inada 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2009,267(8-9):1368-1371
We examined the relation between the 3.1 eV emission band and local structure for Ge+ implanted silica glass by means of photoluminescence, optical and X-ray absorption spectroscopies. In the 2 × 1015 cm?2 implanted sample, a new emission band around 2.7 eV was observed, the origin of which was assigned to the B2α oxygen deficient center and/or small Si clusters in silica. When the Ge+ fluence exceeded 2 × 1016 cm?2, a sharp and intense 3.1 eV emission band replaced the 2.7 eV band. We found that the intense 3.1 eV PL occurred by the prolonged X-ray irradiation onto the 2 × 1015 cm?2 implanted sample. UV–vis absorption and XAFS spectroscopies suggested that the aggregation of atomically dispersed tetravalent (Ge(IV)) atoms into Ge(0) clusters of ~1 nm exhibit strongly correlation with the generation of the 3.1 eV PL. Such nano- and/or subnano-size Ge(0) clusters formed by the X-ray radiation were oxidized and decomposed again to the isolated Ge(IV) atoms, while those produced by the higher Ge+ fluence were stable against the exposure to air. 相似文献
3.
《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》1998,145(3):401-408
Fluorescent soft X-ray carbon Kα emission spectra (XES) have been used to characterize the bonding of carbon atoms in polyimide (PI) and polycarbosilane (PCS) films. The PI films have been irradiated with 40 keV nitrogen or argon ions, at fluences ranging from 1 × 1014 to 1 × 1016 cm−2. The PCS films have been irradiated with 5 × 1015 carbon ions cm−2 of 500 keV and/or annealed at 1000°C. We find that the fine structure of the carbon XES of the PI films changes with implanted ion fluence above 1 × 1014 cm−2 which we believe is due to the degradation of the PI into amorphous C:N:O. The width of the forbidden band as determined from the high-energy cut-off of the C Kα X-ray excitation decreases with the ion fluence. The bonding configuration of free carbon precipitates embedded in amorphous SiC which are formed in PCS after irradiation with C ions or combined treatments (irradiation and subsequent annealing) is close to either to that in diamond-like films or in silicidated graphite, respectively. 相似文献
4.
N.-T.H. Kim-Ngan A.G. Balogh L. Havela T. Gouder 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2010,268(11-12):1875-1879
Thickness, composition, concentration depth profile and ion irradiation effects on uranium nitride thin films deposited on fused silica have been investigated by Rutherford Backscattering Spectroscopy (RBS) using 2 MeV He+ ions. The films were prepared by reactive DC sputtering at the temperatures of ?200 °C, +25 °C and +300 °C. A perfect 1U:1N stoichiometry with a layer thickness of 660 nm was found for the film deposited at ?200 °C. An increase of the deposition temperature led to an enhancement of surface oxidation and an increase of the thickness of the mixed U–N–Si–O layers at the interface. The sample irradiation by 1 MeV Ar+ ion beam with ion fluence of about 1.2–1.7 × 1016 ions/cm2 caused a large change in the layer composition and a large increase of the total film thickness for the films deposited at ?200 °C and at +25 °C, but almost no change in the film thickness was detected for the film deposited at +300 °C. An enhanced mixing effect for this film was obtained after further irradiation with ion fluence of 2.3 × 1016 ions/cm2. 相似文献
5.
J.F. Desjardins M. Chicoine F. Schiettekatte D. Barba F. Martin G.G. Ross 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2009,267(8-9):1317-1320
We investigate the Si nanocrystals (Si-nc) growth and photoluminescence (PL) obtained by Si and Ni co-implantation. After 1 h of annealing at 1000 °C, PL emission between 600 and 1000 nm is observed to be five times higher for samples containing 0.04–0.21 at.% Ni than for samples without Ni. For samples annealed at 1100 °C, a small increase in PL intensity is observed followed by a decrease for Ni contents above 0.3 at.%. Our results are well described by a simple model which assumes that Ni atoms act both as a nucleation center for amorphous Si (a-Si) clusters crystallisation and as a non-radiative recombination site when more than one atom is included in a Si-nc. The nucleation effect is supported by the increase in PL intensity, the increase of PL decay time and the decrease of the a-Si Raman peak intensity at 480 cm?1 for samples annealed at 1000 °C in presence of ~0.1 at.% Ni. Time-resolved PL shows that Ni mainly affects two emission bands. The first band, around 730 nm, is related to an oxygen surface state, suggesting that Ni enhances oxygen bonding with Si-nc. The second band, around 880 nm, is associated to the crystallisation effect induced by Ni at lower annealing temperature. 相似文献
6.
T.S. Iwayama S. Fukaya H. Watanabe T. Hama D.E. Hole 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2009,267(8-9):1328-1331
Si ion implantation was widely used to synthesize specimens of SiO2 containing supersaturated Si and subsequent high temperature annealing induces the formation of embedded luminescent Si nanocrystals. In this work, the potentialities of excimer UV-light (172 nm, 7.2 eV) irradiation and rapid thermal annealing (RTA) to achieve low temperature (below 1000 °C) formation of luminescent Si nanocrystals in SiO2 have been investigated. The Si ions were introduced at acceleration energy of 180 keV to fluences of 7.5 × 1016 and 1.5 × 1017 ions/cm2. The implanted samples were subsequently irradiated with an excimer-UV lamp for 2 h. After the process, the samples were rapidly thermal annealed at 1050 °C for 5 min before furnace annealing (FA) at 900 °C. Photoluminescence spectra were measured at various stages at the process. Effective visible photoluminescence is found to be observed even after FA at 900 °C, only for specimens treated with excimer-UV lamp and RTA, prior to a low temperature FA process. Based on our experimental results, we discuss the mechanism for the initial formation process of the luminescent Si nanocrystals in SiO2, together with the effects with excimer lamp irradiation and RTA process on the luminescence. 相似文献
7.
G.M. Wright R.S. Al E. Alves L.C. Alves N.P. Barradas A.W. Kleyn N.J. Lopes Cardozo H.J. van der Meiden V. Philipps G.J. van Rooij A.E. Shumack W.A.J. Vijvers J. Westerhout E. Zoethout J. Rapp 《Journal of Nuclear Materials》2010,396(2-3):176-180
Tungsten (W) targets have been exposed to high density (ne ? 4 × 1019 m?3), low temperature (Te ? 3 eV) CH4-seeded deuterium (D) plasma in Pilot-PSI. The surface temperature of the target was ~1220 K at the center and decreased radially to ~650 K at the edges. Carbon film growth was found to only occur in regions where there was a clear CII emission line, corresponding to regions in the plasma with Te ? 2 eV. The maximum film thickness was ~2.1 μm after a plasma exposure time of 120 s. 3He nuclear reaction (NRA) analysis and thermal desorption spectroscopy (TDS) determine that the presence of a thin carbon film dominates the hydrogenic retention properties of the W substrate. Thermal desorption spectroscopy analysis shows retention increasing roughly linearly with incident plasma fluence. NRA measures a C/D ratio of ~0.002 in these films deposited at high surface temperatures. 相似文献
8.
E. Alves C. Marques G. Sáfrán Carl J. McHargue 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2009,267(8-9):1464-1467
In this study, we compare and discuss the defect behavior of sapphire single crystals implanted with different fluences (1 × 1016–1 × 1017 cm?2) of carbon and nitrogen with 150 keV. 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 × 1017 cm?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. 相似文献
9.
K. Matsumoto K. Kuriyama K. Kushida 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2009,267(8-9):1568-1570
Carbon-ions, which are expected as an amphoteric impurity, are implanted into ZnO bulk single crystals with a fluence of 1.5 × 1015 cm?2. The carbon-ion implanted ZnO shows the n-type conductivity and the resistivity varies from 6 × 104 Ω cm (for unimplanted samples) to 3 × 10?2 Ω cm (for 800 °C-annealed ones). The Rutherford backscattering (RBS) studies show the existence of the displaced zinc atoms. In photoluminescence (PL) measurements, the broad emission at 2.34 eV observed in un-implanted and as-implanted samples is related to oxygen vacancy and zinc interstitial. After annealing, the weak PL-emission related to carbon donor is observed at 3.06 eV, indicating that the donor level lies at ~310 meV below the conduction band. The carbon-ion implanted ZnO layer with the low resistivity achieved in the present study suggests the possibility of transparent conductive oxide. 相似文献
10.
Mazhar E. Nasir Bruce Hamilton Duncan W.E. Allsop 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2010,268(3-4):251-253
We present X-ray spectroscopy measurements to investigate the chemistry and structure of nanoporous alumina using novel instrument CLASSIX [N.R.J. Poolton, B.M. Towlson, B. Hamilton, D.A. Evans, Nuclear Instruments and Methods in Physics Research B246 (2006) 445] (chemistry luminescence and structure of surfaces by micro-imaging X-ray absorption). X-ray excited optical luminescence (XEOL) measurements show that the porous anodic alumina (PAA) films obtained have blue emission band with a peak position at 2.63 eV (470 nm) which can be attributed to mixed emission from F and F+ centres. The LШ absorption edge of aluminium in porous anodic alumina has been observed at 76.64 eV that shows a chemical shift from pure aluminium. 相似文献
11.
《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》1999,147(1-4):171-174
Proton implantation in GaN is found to reduce the free carrier density through two mechanisms – first, by creating electron and hole traps at around EC − 0.8 eV and EV + 0.9 eV that lead to compensation in both n- and p-type material, and second, by leading to formation of (AH)° complexes, where A is any acceptor (Mg, Ca, Zn, Be, Cd). The former mechanism is useful in creating high resistivity regions for device isolation, whereas the latter produces unintentional acceptor passivation that is detrimental to device performance. The strong affinity of hydrogen for acceptors leads to markedly different redistribution behavior for implanted H+ in n- and p-GaN due to the chemical reaction to form neutral complexes in the latter. The acceptors may be reactivated by simple annealing at ⩾600°C, or by electron injection at 25–150°C that produces debonding of the (AH)° centers. Implanted hydrogen is also strongly attracted to regions of strain in heterostructure samples during annealing, leading to pile-up at epi–epi and epi–substrate interfaces. IR spectroscopy shows that implanted hydrogen also decorates VGa defects in undoped and n-GaN. 相似文献
12.
S. Asad Ali Rajesh Kumar F. Singh P.K. Kulriya Rajendra Prasad 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2010,268(11-12):1813-1817
Swift Heavy Ion (SHI) irradiation of the polymeric materials modifies their physico-chemical properties. Lexan polycarbonate films were irradiated with 95 MeV oxygen ions to the fluences of 1010, 1011, 1012, 1013 and 2 × 1013 ions/cm2. Characterization of optical, chemical, electrical and structural modifications were carried out by UV–Vis spectroscopy, FTIR spectroscopy, Dielectric measurements and X-ray Diffraction. A shift in the optical absorption edge towards the red end of the spectrum was observed with the increase in ion fluence. The optical band gap (Eg), calculated from the absorption edge of the UV–Vis spectra of these films in 200–800 nm region varied from 4.12 eV to 2.34 eV for virgin and irradiated samples. The cluster size varied in a range of 69–215 carbon atoms per cluster. In FTIR spectra, appreciable modification in terms of breaking of the cleavaged C–O bond of carbonate and formation of phenolic O–H bond was observed on irradiation. A rapidly decreasing trend in dielectric constant is observed at lower frequencies. The dielectric constant increases with fluence. It is observed that the loss factor increases moderately with fluence and it may be due to scissoring of polymer chains, resulting in an increase in free radicals. A sharp increase in A.C. conductivity in pristine as well as in irradiated samples is observed with frequency and is attributed to scissoring of polymer chains. XRD analyses show significant change in crystallinity with fluence. A decrease of ~9.02% in crystallite size of irradiated sample at the fluence of 2 × 1013 ions/cm2 is observed. 相似文献
13.
《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》1999,147(1-4):127-131
Epitaxial silicon samples of n-type have been implanted with 850 keV protons at a dose of 5 × 1013H+ cm−2. Subsequent in-diffusion of platinum at 700°C for 30 min resulted in the presence of a single deep level, which is attributed to the platinum acceptor level, at 0.23 eV below the conduction band edge. Depth profiling of this level shows that the substitutional platinum is following the vacancy profile in the peak region around the projected range for the protons. In addition, at more shallow depths, a strong increase of the platinum concentration is also observed. Without ion-implantation, no deep levels are detected after in-diffusion at 700°C, while at 800°C, the Pt deep level concentration is inferior to the one reached after pre-implantation with the above dose. After in-diffusion at 600°C into the implanted sample, many defects are observed. One of these is the substitutional platinum, while the others are considered to be of interstitial nature, due to the fact that their maximum concentration is found to be deeper than the projected range of the irradiation. The role of these latter defects in the process of platinum proximity gettering is discussed. 相似文献
14.
15.
F.L. Bregolin M. Behar U.S. Sias E.C. Moreira 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2009,267(8-9):1314-1316
Up to the present, photoluminescence (PL) was obtained from near stoichiometric or amorphous Si nitride films (SiNx) after annealing at high temperatures. As a consequence, the existence of PL bands has been reported in the 400–900 nm range. In the present contribution, we report the first PL results obtained by Si implantation into a stoichiometric 380 nm Si3N4 film. The Si excess is obtained by a 170 keV Si implantation at different temperatures with a fluence of Φ = 1017 Si/cm2. Further, we have annealed the samples in a temperature range between 350 and 900 °C in order to form the Si precipitates. PL measurements were done using an Ar laser as an excitation source, and a broad PL band basically centered at 910 nm was obtained. We show that the best annealing condition is obtained at Ta = 475 °C for the samples implanted at 200 °C, with a PL yield 20% higher than the obtained at room temperature implantation. Finally, we have varied the implantation fluence and, consequently, the Si nanocrystals size. However, no variation was observed nor in the position neither in the intensity of the PL band. We concluded that the PL emission is due to radiative states at the matrix and the Si nanocrystals interface, as previously suggested in the literature. 相似文献
16.
T.A. Harriman D.A. Lucca J.-K. Lee M.J. Klopfstein K. Herrmann M. Nastasi 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2009,267(8-9):1232-1234
A study of the effects of Ar ion implantation on the structural transformation of single crystal Si investigated by confocal Raman spectroscopy is presented. Implantation was performed at 77 K using 150 keV Ar++ with fluences ranging from 2 × 1013 to 1 × 1015 ions/cm2. The Raman spectra showed a progression from crystalline to highly disordered structure with increasing fluence. The 520 cm?1 c-Si peak was seen to decrease in intensity, broaden and exhibit spectral shifts indicating an increase in lattice disorder and changes in the residual stress state. In addition, an amorphous Si band first appeared as a shoulder on the 520 cm?1 peak and then shifted to lower wavenumbers as a single broadband peak with a spectral center of 465 cm?1. Additionally, the emergence of the a-Si TA phonon band and the decrease of the c-Si 2TA and 2TO phonon bands also indicated the same structural transition from crystalline to highly disordered. The Raman results were compared to those obtained by channeling RBS. 相似文献
17.
M. Usman M. Nour A.Yu. Azarov A. Hallén 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2010,268(11-12):2083-2085
Ion implantation induced damage formation and subsequent annealing in 4H–SiC in the temperature range of 100–800 °C has been investigated. Silicon Carbide was implanted at room temperature with 200 keV 40Ar ions with two implantation fluences of 4 × 1014 and 2 × 1015 ions/cm2. The samples were characterized by Rutherford backscattering and nuclear reaction analysis techniques in channeling mode using 2.00 and 4.30 MeV 4He ion beams for damage buildup and recovery in the Si and C sublattices, respectively. At low ion fluence, the restoration of the Si sublattice is evident already at 200 °C and a considerable annealing step occurs between 300 and 400 °C. Similar results have been obtained for the C sublattice using the nuclear resonance reaction for carbon, 12C(α,α)12C at 4.26 MeV. For samples implanted with the higher ion fluence, no significant recovery is observed at these temperatures. 相似文献
18.
《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》1998,143(3):333-341
Damage accumulation and annealing in 6H-silicon carbide (α-SiC) single crystals have been studied in situ using 2.0 MeV He+ RBS in a 〈0 0 0 1〉-axial channeling geometry (RBS/C). The damage was induced by 550 keV Si+ ion implantation (30° off normal) at a temperature of −110°C, and the damage recovery was investigated by subsequent isochronal annealing (20 min) over the temperature range from −110°C to 900°C. At ion fluences below 7.5 × 1013 Si+/cm2 (0.04 dpa in the damage peak), only point defects appear to be created. Furthermore, the defects on the Si sublattice can be completely recovered by thermal annealing at room temperature (RT), and recovery of defects on the C sublattice is suggested. At higher fluences, amorphization occurs; however, partial damage recovery at RT is still observed, even at a fluence of 6.6 × 1014 Si+/cm2 (0.35 dpa in the damage peak) where a buried amorphous layer is produced. At an ion fluence of 6.0 × 1015 Si+/cm2 (−90°C), an amorphous layer is created from the surface to a depth of 0.6 μm. Because of recovery processes at the buried crystalline–amorphous interface, the apparent thickness of this amorphous layer decreases slightly (<10%) with increasing temperature over the range from −90°C to 600°C. 相似文献
19.
《Journal of Nuclear Materials》2006,348(1-2):79-86
The interaction of isotopic oxygen (18O2) with Zircaloy-4 (Zry-4) at 150 and 300 K has been studied using Auger electron spectroscopy (AES) and temperature-programmed desorption (TPD) methods. AES reveals the oxidation of the Zry-4 surface, reflected in shifts of the Zr(MNV) and Zr(MNN) features by about 5.5 and 3.0 eV, respectively, for both adsorption temperatures. The O(KLL)/Zr(MNN) Auger peak-to-peak height ratios as a function of exposure show the same trends at both temperatures. Following 18O2 adsorption at 150 or 300 K, TPD experiments show hydrogen desorption near 400 K that is attributed to the presence of a surface-stabilized form of hydrogen. Additionally, water (H218O and H216O) desorption below 200 K and above 700 K is observed after 150 K oxygen adsorption. However, after oxygen adsorption at 300 K the only significant desorption features are from isotopic water (H218O). These findings indicate that mass transport involving the near-surface region contributes to the observed desorption, and that this behavior is dependent on the original adsorption temperature. Charging experiments using D2 prior to and after 18O2 adsorption were also performed and support our conclusions about the role of surface–subsurface mass transport in this system. 相似文献
20.
L. Marot G. De Temmerman R.P. Doerner K. Umstadter R.S. Wagner D. Mathys M. Duggelin E. Meyer 《Journal of Nuclear Materials》2013,432(1-3):388-394
The combined effect of hydrogen plasma exposure and surface heating, either continuous or by short laser pulses (5 ns), on the surface morphology of rhodium layers has been studied. Investigations were performed by reflectivity measurements, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and atomic force microscope (AFM). While surfaces exposed at room temperature exhibit little modifications, strong surface changes are observed for surface temperatures higher than 250 °C. At 500 °C, the plasma exposed surface exhibits a nanoscale structure (50–100 nm) with a high level of porosity and a low reflectivity. Additional laser irradiation of the surface strongly enhances the observed surface damage. Localized surface melting is observed with craters extending deep into the substrate together with a dense network of voids. 相似文献