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1.
Molecular beam epitaxy (MBE) grown AlN thin layer on sapphire substrates have been implanted with Cr+ ions for various dose from 1013 to 1015 cm−2. The analyses were carried out by an X-ray diffractometer (XRD), Raman spectroscopy, a spectrophotometer and spectroscopic ellipsometry (SE) for structural and optical analyses. E2(high) and A1(LO) Raman modes of AlN layer have been observed and analyzed. The behavior of Raman shift and the variation in intensity and in peak width of Raman modes as a function of ions flux are explained on the basis of chromium substituting aluminum atom and implantation-induced lattice damage. Both Raman and X-ray analyses reveal that the incorporation of chromium atoms increases in the host lattice with the increasing of Cr ions fluence. The band gap energy was determined by using transmission spectra. It was found that the band gap energy decreases as the ion dose increases. The band gap of the unimplanted AlN is 6.02 eV and it decreases down to 5.92 eV for the Cr+-implanted AlN with a ion dose of 1×1015 cm−2. Optical properties such as optical constants of the samples were examined by using a spectroscopic ellipsometer. It was observed that the refractive index (n) decreases with the increasing of ion dose.  相似文献   

2.
Mn ions were implanted into metal organic chemical vapour deposition (MOCVD)-grown GaN with dose ranging from 1014 to 5×1016 cm−2. Isochronal annealing at 800 and 850 °C has been carried out after implantation of the samples. Photoluminescence measurements were carried out on the implanted samples before and after annealing. A peak found at 3.34 eV in the spectra of implanted samples after annealing at 850 °C is attributed to the stacking faults. Blue and green luminescence bands have been observed suppressed and an oxygen-related peak appeared at 3.44 eV in the PL spectra. The suppression of blue and green luminescence bands has been assigned to dissociation of VGaON complex. Near-band-edge (NBE) peak exhibited a blue shift after 800 °C anneal and then red shift to restore its original energy position when annealed at 850 °C.  相似文献   

3.
In the present study, we report the photoluminescence (PL) study of nanoparticles of ZnS implanted with Cu+ ions at the doses of 5×1014, 1×1015 and 5×1015 ions/cm2 and annealed at 200 and 300 °C. The photoluminescence spectra of the samples implanted at lower doses of 5×1014 and 1×1015 ions/cm2 and annealed at 200 and 300 °C showed peaks at around 406, 418 and 485 nm. The PL emission peak at 485 nm was attributed to the transition of electrons from conduction band of ZnS to the impurity level formed by the implanted Cu+ ions. In the PL spectrum of the sample implanted at the highest dose of 5×1015 ions/cm2, in addition to the emission peaks observed in the PL spectra of the samples implanted at lower doses, a peak at around 525 nm, the intensity of which decreased with increase in the annealing temperature, was observed. The emission peak at 525 nm was attributed to the transitions between sulfur and zinc vacancy levels. The full width at half maximum (FWHM) of the emission peak at 406 nm was observed to decrease with increase in annealing temperature, indicating lattice reconstruction. The observation of copper ion impurity related peak at 485 nm in the PL spectra of samples of the present study indicated that the doping of copper ions into the ZnS lattice is achievable by implanting Cu+ ions followed by annealing.  相似文献   

4.
ZnO films prepared by radio frequency magnetron sputtering were singly or sequentially implanted with 120 keV Fe ions at a fluence of 5 × 1016 ions/cm2 and 20 keV C ions at a fluence of 3 × 1015 ions/cm2. Magnetic and optical properties as well as structures of the films have been investigated using various techniques. Magnetic measurements show that the as-deposited ZnO film presents room temperature ferromagnetism. Single Fe or C ion implantation has no contribution to enhancement in the film magnetism, while magnetic moment increases distinctly in the Fe and C ions sequentially implanted film. Results from structural measurements reveal that Fe nanoparticles are formed in the Fe singly implanted ZnO film. The post C implantation induces dissolution of Fe nanoparticles and promotes Fe atoms to substitute Zn atoms in the lattice. Based on the structural results, the effect of magnetic enhancement has been tentatively interpreted.  相似文献   

5.
Single crystalline ZnO films were grown on c-plane GaN/sapphire (0 0 0 1) substrates by molecular beam epitaxy. Cr+ ions were implanted into the ZnO films with three different doses, i.e., 1 × 1014, 5 × 1015, and 3 × 1016 cm−2. The implantation energy was 150 keV. Thermal treatment was carried out at 800 °C for 30 s in a rapid thermal annealing oven in flowing nitrogen. X-ray diffraction (XRD), atomic force microscopy, Raman measurements, transmission electron microscopy and superconducting quantum interference device were used to characterize the ZnO films. The results showed that thermal annealing relaxed the stress in the Cr+ ions implanted samples and the implantation-induced damage was partly recovered by means of the proper annealing treatment. Transmission electron microscopy measurements indicated that the first five monolayers of ZnO rotated an angle off the [0 0 0 1]-axis of the GaN in the interfacial layer. The magnetic-field dependence of magnetization of annealed ZnO:Cr showed ferromagnetic behavior at room temperature.  相似文献   

6.
In order to study the effect of copper ion implantation on the aqueous corrosion behavior, samples of zircaloy-4 were implanted with copper ions with fluences ranging from 1 × 1016 to 1 × 1017 ions/cm2, using a metal vapor vacuum arc source (MEVVA) operated at an extraction voltage of 40 kV. The valence states and depth distributions of elements in the surface layer of the samples were analyzed by X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES), respectively. Glancing angle X-ray diffraction (GAXRD) was employed to examine the phase transformation due to the copper ion implantation. The potentiodynamic polarization technique was employed to evaluate the aqueous corrosion resistance of implanted zircaloy-4 in a 1 M H2SO4 solution. It was found that a significant improvement was achieved in the aqueous corrosion resistance of zircaloy-4 implanted with copper ions when the fluence is smaller than 5 × 1016 ions/cm2. The corrosion resistance of implanted samples declined with increasing the fluence. Finally, the mechanism of the corrosion behavior of copper-implanted zircaloy-4 was discussed.  相似文献   

7.
Comprehensive and systematic optical activation studies of Si-implanted GaN grown on sapphire substrates have been made as a function of ion dose and anneal temperature. Silicon ions were implanted at 200 keV with doses ranging from 1×1013 to 5×1015 cm−2 at room temperature. The samples were proximity cap annealed from 1250 to 1350 °C with a 500-Å-thick AlN cap in a nitrogen environment. The results of photoluminescence measurements made at 3 K show a very sharp neutral-donor-bound exciton peak along with a sharp donor-acceptor pair peak after annealing at 1350 °C for 20 s, indicating excellent implantation damage recovery. The results also indicate the AlN cap protected the implanted GaN layer very well during high temperature annealing without creating any significant anneal-induced damage. This observation is consistent with the electrical activation results for these samples.  相似文献   

8.
We report on photoluminescence and Raman studies of Xe ion-implanted diamond. Several natural and high-purity artificial diamonds implanted within the wide dose range of 1010-5×1014 ion/cm2 were studied. The room temperature luminescence of the Xe center consists of two zero phonon lines, at 813 nm (strong) and 794 nm (weak). The dose dependences of photoluminescence and Raman spectra were studied. For doses less than 1013 ion/cm2, the luminescence intensity grows with the implantation dose linearly. The defect-induced photoluminescence quenching was observed for doses equal or more than 1013 ion/cm2. Possible models of the Xe center will be discussed. The nature of damages induced by ion implantation at different doses was analyzed using micro-Raman spectroscopy.  相似文献   

9.
Diamond-like carbon (DLC) films were deposited on Si(1 0 0) substrates using plasma deposition technique. The deposited films were irradiated using 2 MeV N+ ions at fluences of 1×1014, 1×1015 and 5×1015 ions/cm2. Samples have been characterized by using Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and high-resolution transmission electron microscopy (HRTEM). Analysis of Raman spectra shows a gradual shift of both D and G band peaks towards higher frequencies along with an increase of the intensity ratio, I(D)/I(G), with increasing ion fluence in irradiation. These results are consistent with an increase of sp2 bonding. XPS results also show a monotonic increase of sp2/sp3 hybridization ratio with increasing ion fluence. Plan view TEM images show the formation of clusters in the irradiated DLC films. HRTEM micrographs from the samples irradiated at a fluence of 5×1015 ions/cm2 show the lattice image with an average interplanar spacing of 0.34 nm, revealing that the clusters are graphite clusters. The crystallographic planes in these clusters are somewhat distorted compared to the perfect graphite structure.  相似文献   

10.
Ag nanoclusters embedded in silica matrix were formed by ion implantation to different doses. The intensity of surface plasmon resonance absorption enhances with the increasing of the implanted dose, but decreases at dose higher than 1×1017 ions/cm2 due to the surface sputtering effect. The lattice distortion of nanoclusters has been observed using a high-resolution transmission electron microscope. The positions of the resonance peaks are red-shifted after the samples were annealed in oxidizing atmosphere at elevated temperatures. The red shift is mainly attributed to the interactions of Ag nanoclusters with diffused oxygen and nanovoids.  相似文献   

11.
The amorphization of crystalline Si (100) under 125 keV O+ ion implantation is investigated in the fluence range 1×1014 ions/cm2 to 1×1016 ions/cm2. The microstructure of the O+ implanted Si is modeled from ellipsometric data using a two phase, multilayer model within Bruggeman effective medium approximation (BEMA). The transition from the crystalline to the amorphous phase is found to be smooth and progressive. From a detailed analysis of the moments of the dielectric spectra and laser Raman spectroscopy, we infer that the amorphization occurs through a progressive disruption of long-range order caused by the overlap of amorphous nanozones. The dielectric spectrum of the fully amorphous phase is characterized using the Forouhi-Bloomer interband model.  相似文献   

12.
We report on the formation of the planar waveguide by 550 keV O ion followed by 250 keV O ion implantation in lithium niobate (LiNbO3), at fluences of 6 × 1014 ions/cm2 and 3 × 1014 ions/cm2, respectively. The Rutherford backscattering/channeling spectra have shown the atomic displacements in the damage region before and after annealing. A broad and nearly homogeneous damage layer has been formed by double-energy ion implantation after annealing. Both the dark mode spectra and the data of refractive index profile verified that the extraordinary refractive index was enhanced in the ion implanted region of LiNbO3. A homogeneous near-field intensity profile was obtained by double-low-energy ion implantation. There is a reasonable agreement between the simulated modal intensity profile and the experimental data. The estimated propagation loss is about 0.5 dB/cm.  相似文献   

13.
《Physics letters. A》2001,286(5):332-337
The weak damage induced by 0.8 MeV Si ion implantation in the Al0.25Ga0.75As films epitaxially grown on GaAs substrates was studied by using Rutherford backscattering spectrometry/channeling (RBS/C) and Raman spectroscopy. RBS/C spectra measured from the implanted samples showed rather low damage level induced by the ion implantation with ion dose from 1×1014 to 5×1015 cm−2. The Raman spectra were measured on these samples. Two kinds of phonon modes, GaAs-like and AlAs-like, are observed, which indicate the existence of multiple phonon vibrational modes in the epitaxial Al0.25Ga0.75As films on the GaAs substrate. Compared with the unimplanted sample, the Raman photon peaks for the implanted sample shift gradually to lower energy with the increase of the implantation dose. The strains induced in the implanted layer were also evaluated from the Raman spectra. The result from high resolution double crystal X-ray diffractometry (HRXRD) also verified the evolution of the strains in the implanted layers.  相似文献   

14.
Carbon ions at 40 keV were implanted into (1 0 0) high-purity p-type silicon wafers at 400 °C to a fluence of 6.5 × 1017 ions/cm2. Subsequent thermal annealing of the implanted samples was performed in a diffusion furnace at atmospheric pressure with inert nitrogen ambient at 1100 °C. Time-of-flight energy elastic recoil detection analysis (ToF-E ERDA) was used to investigate depth distributions of the implanted ions. Infrared transmittance (IR) and Raman scattering measurements were used to characterize the formation of SiC in the implanted Si substrate. X-ray diffraction analysis (XRD) was used to characterize the crystalline quality in the surface layer of the sample. The formation of 3C-SiC and its crystalline structure obtained from the above mentioned techniques was finally confirmed by transmission electron microscopy (TEM). The results show that 3C-SiC is directly formed during implantation, and that the subsequent high-temperature annealing enhances the quality of the poly-crystalline SiC.  相似文献   

15.
High purity alumina ceramics (99% Al2O3) was implanted by copper ion and titanium ion in a metal vapour vacuum arc (MEVVA) implanter, respectively. The influence of implantation parameters was studied varying ion fluence. The samples were implanted by 68 keV Cu ion and 82 keV Ti ion with fluences from 1 × 1015 to 1 × 1018 ions/cm2, respectively. The as-implanted samples were investigated by scanning electron microscopy (SEM), glancing X-ray diffraction (GXRD), scanning Auger microscopy (SAM), and four-probe method. Different morphologies were observed on the surfaces of the as-implanted samples and clearly related to implantation parameters. For both ion implantations, the sheet resistances of the alumina samples implanted with Cu and Ti ion fluences of 1 × 1018 ions/cm2, respectively, reached the corresponding minimum values because of the surface metallization. The experimental results indicate that the high-fluence ion implantation resulted in conductive layer on the surface of the as-implanted high purity alumina ceramics.  相似文献   

16.
Among the family of rare earth (RE) dopants, the doping of first member Ce into GaN is the least studied system. This article reports structure properties of Ce‐doped GaN realized by technique of ion implantation. Ce ions were implanted into metal organic chemical vapor deposition grown n‐ and p‐GaN/sapphire thin films at doses 3 × 1014 and 2 × 1015 cm−2. X‐ray diffraction scans and Raman scattering measurements exhibited expansion of lattice in the implanted portion of the samples. First order Raman scattering spectra show appearance of several disorder‐activated Raman scattering modes in addition to typical GaN features. A dose‐dependent decrease in intensity of E2 mode was observed in Raman the spectra of the implanted samples. Ultraviolet Raman spectra of implanted samples show complete quenching of photoluminescence emission and appearance of multiple A1(LO) phonon scattering modes up to fifth order. Moreover, a decrease in intensity and an increase in line width of LO modes as a function of wavenumber were observed for implanted samples. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

17.
We report on the low energy oxygen implantation induced improvement in crystallinity and optical properties of surface modified ZnO single crystals. Undoped ZnO (0 0 0 1) single crystal wafers are implanted with 100 keV oxygen ions at a dose of 5 × 1013 and 5 × 1014 cm−2 and subsequently annealed at 500 and 600 °C in oxygen ambient. The as-implanted and annealed ZnO wafers are studied by Rutherford back scattering spectrometry (RBS), channeling, Raman, photoluminescence (PL), and Fourier transform infrared spectroscopy (FTIR). Channeling studies show a relatively high χmin (>20%) in the virgin ZnO wafer. After implantation and two-step annealing, RBS studies show improved crystallinity. Raman line width analysis for the mode indicates reduction in strain in the annealed samples as compared to the virgin ZnO wafer. As-implanted samples show drastic quenching of the near band-edge (NBE) PL band due to defects created by the implantation. However, after two-step annealing, the low-dose implanted sample show a five-fold increase in intensity ratio of NBE band (376 nm) to defect related broad band (∼530 nm) at room temperature. Implantation induced changes in the composition and improved crystallinity in the near surface region is accounted for the major improvement in the PL emission.  相似文献   

18.
AZ31 samples were implanted with yttrium ions with fluences of 5 × 1016, 1 × 1017 and 5 × 1017 ions/cm2, using a metal vapor vacuum arc source at an extraction voltage of 45 kV. The surfaces of the implanted samples were then analyzed by Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS). It was found that after treatment a pre-oxidation layer was formed, and the higher the fluence, the thicker the pre-oxidation layer was. The valence states showed that yttrium existed in the form of Y2O3. Isothermal oxidation tests have been conducted in pure oxygen at 773 K for 90 min to evaluate the oxidation behavior of the implanted samples. The results indicate that after implantation the oxidation resistance of the samples was significantly improved. Moreover, the greater the fluence, the better the oxidation resistance has been achieved. The characterization of the implanted layers after isothermal oxidation was examined by SEM, AES and XPS. From the results, it can be found that the thickness of the oxide scale formed on the implanted surfaces have been greatly decreased, and there is no obvious change for both the thickness of the pre-oxidation layer and the valence states of the elements after oxidation.  相似文献   

19.
High density polyethylene (HDPE) has been modified by Ag+ ion implantation with the energy of 60 keV. The total amount of implanted silver ions was 1, 5 and 12 × 1015 ions/cm2. The surface topography was observed by atomic force microscopy (AFM), while the surface composition changes were detected using phase imaging AFM. Surface topography changes were studied in detail using 3D surface parameters analyses. The average roughness decreased for the implanted HDPE indicating the flattening of the surface. Phase AFM images indicated the homogenization of the polyethylene during ion implantation, while histogram analyses confirmed the change in surface composition.  相似文献   

20.
ZnO [0 0 0 1] crystals were irradiated at room temperature with Tb+ ions of 400 keV with fluences from 1×1016 to 2×1017 cm−2. The implanted layer was examined by several methods, including radioluminescence (RL), Rutherford backscattering spectrometry (RBS) and optical spectroscopy. The optical extinction spectra were simulated using Mie scattering theory. Absorption spectra predicted by Mie theory for particles of decreasing diameter were compared with those obtained experimentally. Some qualitative agreement between theoretical and experimental data was achieved. It was also shown that the intensities of the characteristic green emission bands associated with Tb produced by 5D47Fj=5,4 transitions have increased about 8 times after annealing. Optical spectroscopy and radioluminescence data have revealed that the ion implantation is a promising tool for synthesizing Tb nanoparticles in the ZnO surface. The Tb nanoparticles exhibit a rather weak plasma resonance.  相似文献   

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