排序方式: 共有15条查询结果,搜索用时 78 毫秒
1.
2.
3.
M. Schade O. Varlamova J. Reif H. Blumtritt W. Erfurth H. S. Leipner 《Analytical and bioanalytical chemistry》2010,396(5):1905-1911
We report on the structural investigation of self-organized periodic microstructures (ripples) generated in Si(100) targets
after multishot irradiation by approximately 100-fs to 800-nm laser pulses at intensities near the single shot ablation threshold.
Inspection by surface sensitive microscopy, e.g., atomic force microscopy (AFM) or scanning electron microscopy (SEM), and
conventional and high-resolution transmission electron microscopy reveal complex structural modifications upon interaction
with the laser: even well outside the ablated area, the target surface exhibits fine ripple-like undulations, consisting of
alternating crystalline and amorphous silicon. Inside the heavily modified area, amorphous silicon is found only in the valleys
but not on the crests which, instead, consist of highly distorted crystalline phases, rich in defects. 相似文献
4.
Koksal Yildiz Unal Akgul Hartmut S. Leipner Yusuf Atici 《Applied Physics A: Materials Science & Processing》2014,117(3):1387-1392
The film of thermoelectric ternary p-type (Bi0.15Sb0.85)2Te3 was deposited on polyimide foil substrate at 168 °C using direct-current magnetron sputtering. Microstructural investigations of the film were performed by electron microscopy techniques. SEM observations showed that the film surface consisted of large-sized particulates with small-sized particles and also mound-like crystal agglomerates in some areas. Chemical composition of the film was analyzed using energy-dispersive X-ray spectrometer (EDS). It has been observed that the EDS results were in an agreement with nominal composition for the film. Detailed microstructural investigations were carried out using transmission electron microscopy (TEM). TEM images and selected area electron diffraction patterns showed that the film has randomly oriented polycrystalline grain structure. High-resolution TEM images indicated that the microstructure of film also contained nano-crystal structure, smaller than 10 nm. 相似文献
5.
Maurizio Roczen Enno Malguth Martin Schade Andreas Schöpke Abdelazize Laades Michael Blech Orman Gref Thomas Barthel Jan Amaru Töfflinger Manfred Schmidt Hartmut S. Leipner Lars Korte Bernd Rech 《Journal of Non》2012,358(17):2253-2256
Two different growth mechanisms are compared for the fabrication of Si/SiO2 nanostructures on crystalline silicon (c-Si) to be used as hetero-emitter in high-efficiency solar cells: (1) The decomposition of substoichiometric amorphous SiOx (a-SiOx) films with 0 < x < 1.3 and (2) the dewetting of thin amorphous silicon (a-Si) layers.The grown layers are investigated with regard to their structural properties, their passivation quality for c-Si wafer substrates and their electrical properties in order to evaluate their suitability as a nanodot hetero-emitter. While by layer decomposition, no passivating nanodots could be formed, the dewetting process allows fabricating nanodot passivation layers at temperatures as low as 600 °C. The series resistance through Ag/[Si-nanodots in SiO2]/c-Si/Al structures for dewetting is similar to nanostructured silicon rich SiOx films. Still, a nanodot hetero-emitter which exhibits both a satisfying passivation of the substrate and induces a high band bending by doping at the same time could not be fabricated yet. 相似文献
6.
Molten salt hydrates proved to be alternative solvents to cellulose. Toinvestigate the reasons for this dissolving ability, information about thesolvent–cellulose interactions is essential. As well as 13CHR NMR, 7Li NMR was used to obtain further insight into thisproblem.After comparing several molten salt hydrates, the 7Li NMR spectrarevealed a smaller shielding of the lithium cation for not dissolving than fordissolving and swelling cellulose systems. In most solvent systems theshieldingat the 7Li nuclei increases with the cellulose concentration. 2D7Li-1H HOESY NMR was successfully applied to verify thepresence of cellobiose, used as a model compound for cellulose, in the firstco-ordination sphere of the lithium cation. 相似文献
7.
8.
M.?ElsayedEmail author R.?Krause-Rehberg B.?Korff I.?Ratschinski H.?S.?Leipner 《The European Physical Journal B - Condensed Matter and Complex Systems》2013,86(8):358
Positron annihilation spectroscopy was applied to investigate the nature and thermal behavior of defects induced by Cu diffusion in Zn-doped p-type GaAs crystals. Cu atoms were intentionally introduced in the GaAs lattice through thermally activated diffusion from a thin Cu capping layer at 1100 °C under defined arsenic vapor pressure. During isochronal annealing of the obtained Cu-diffused GaAs in the temperature range of 450?850 K, vacancy clusters were found to form, grow and finally disappear. We found that annealing at 650 K triggers the formation of divacancies, whereas further increasing in the annealing temperature up to 750 K leads to the formation of divacancy-copper complexes. The observations suggest that the formation of these vacancy-like defects in GaAs is related to the out-diffusion of Cu. Two kinds of acceptors are detected with a concentration of about 1016 ? 1017 cm?3, negative ions and arsenic vacancy copper complexes. Transmission electron microscopy showed the presence of voids and Cu precipitates which are not observed by positron measurements. The positron binding energy to shallow traps is estimated using the positron trapping model. Coincidence Doppler broadening spectroscopy showed the presence of Cu in the immediate vicinity of the detected vacancies. Theoretical calculations suggested that the detected defect is V Ga V As-2CuGa. 相似文献
9.
M. Schade N. Geyer B. Fuhrmann F. Heyroth H. S. Leipner 《Applied Physics A: Materials Science & Processing》2009,95(2):325-327
We report on the characterization of hexagonally ordered, vertically aligned silicon nanowires (SiNW) by means of analytical
transmission electron microscopy. Combining colloidal lithography, plasma etching, and catalytic wet etching arrays of SiNW
of a sub-50 nm diameter with an aspect ratio of up to 10 could be fabricated. Scanning transmission electron microscopy has
been applied in order to investigate the morphology, the internal structure, and the composition of the catalytically etched
SiNW. The analysis yielded a single-crystalline porous structure composed of crystalline silicon, amorphous silicon, and SiO
x
with x≤2. 相似文献
10.
Rössel M Höche HR Leipner HS Völtzke D Abicht HP Hollricher O Müller J Gablenz S 《Analytical and bioanalytical chemistry》2004,380(1):157-162
Due to their outstanding dielectric and ferroelectric properties, barium titanate (BaTiO3)-based ceramics have found many applications in electronic devices. To optimise the final quality of such ceramics, a detailed knowledge of the complex processes involved in the formation of BaTiO3 is required. The phase formation process in ordered structures of the BaCO3/TiO2 system was analysed by X-ray diffraction and by Raman spectral imaging (RSI) as a function of the annealing temperature. RSI was used for the first time as a locally resolving method for phase analysis, and proved to be a useful tool in examining the formation process of BaTiO3 starting from spherical, core–shell structured precursors of the type TiO2 core/BaCO3 shell. The Raman spectra of different BaO–TiO2 phases appearing as intermediate phases during the formation of BaTiO3 were recorded for separately-prepared pure substances. Using these spectra as fingerprints, and choosing phase filters by setting wave number windows, phase landscape pictures of the samples at different temperatures during the genesis of BaTiO3 could be created with a lateral resolution of up to 200 nm. These pictures confirm shell-like formation of the different barium titanate phases according to the diffusion of barium and oxygen ions from the Ba-rich shell into the TiO2 core. At an intermediate state of the phase formation process, the phase sequence Ba2TiO4, BaTiO3, BaTi2O5, BaTi4O9 and BaTi5O11 to TiO2 was detected from the outer to the inner parts of the core–shell structures. 相似文献