共查询到20条相似文献,搜索用时 15 毫秒
1.
A.F. Zatsepin V.A. Pustovarov V.S. Kortov E.A. Buntov H.-J. Fitting 《Journal of Non》2009,355(18-21):1119-1122
In this paper we present results of a low-temperature time-resolved photoluminescence (PL) investigation of thin SiO2 films implanted with silicon ions. In addition to the luminescence of well-known ODCs, some other bands are present in the low-energy region of PL spectra that are attributed to silicon nanoclusters (quantum dots – SiQDs), excitons and hydrogen-related species (HRS). Specific features of SiQD and HRS bands are the nanosecond kinetics and unusual “stepped” PL excitation spectrum in the 3.5–7.5 eV range. The possible origin of discovered phenomena is discussed. The obtained results are interpreted taking into account the interference of exciting radiation and dimensional quantization effects. 相似文献
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H.-J. Fitting T. BarfelsA.N. Trukhin B. SchmidtA. Gulans A. von Czarnowski 《Journal of Non》2002,303(2):218-231
Thermally grown SiO2 layers of thickness d=500 nm have been implanted by Ge+, Si+, and O+ ions of energy 350, 150, and 100 keV, respectively, and a uniform implantation dose of Di=5×1016 ions/cm2. Thus the implantation profiles are expected with a concentration maximum of nearly 4 at.% at the half-depth dm≅250 nm of the SiO2 layers. After thermal annealing to 900 °C for 1 h in dry nitrogen or vacuum the typical violet luminescence band (λ=400 nm) of the Ge+ implanted centers is increased more than 200-fold and the Ge luminescent center depth profile is shifted from about 250 to 170 nm towards the surface as determined by cathodoluminescence (CL) depth profiling. Implanting oxygen increases the red band (λ=650 nm) but does not affect the blue band (λ=460 nm). Silicon surplus increases the amplitude of the blue (B) luminescence, but reduces the amplitude of the red (R) one. Studying the irradiation dose dependence of these blue and red bands we have established defect kinetics in SiO2 including six main defects and precursors, including the non-bridging oxygen hole center for the red luminescence, the twofold-coordinated silicon as the oxygen deficient center ODC(2) for the blue luminescence and the mobile oxygen as the main transmitter between precursors and the radiation induced defects. The kinetics are described by a set of eight differential equations which predict the dose dependence of the CL. 相似文献
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The redeposition of electrode material (Ni, Cr, Al) and material of a Nb layer on silicon surface during plasma etching of Nb, SiO2 and Si by a CF4 plasma has been investigated by Rutherford Back Scattering spectrometry. It is shown that a steady state exists, what causes a Nb contamination of etched Si surfaces. Obviously this steady state concentration (Nb)ads is influenced by additional redeposition of non-etchable electrode material as Ni, Cr and Al. 相似文献
4.
Kenichi Kawaguchi Hiroji Ebe Mitsuru Ekawa Akio Sugama Yasuhiko Arakawa 《Journal of Crystal Growth》2010,312(20):2919-2922
Crystal growth of GaAs layers and InAs quantum dots (QDs) on the GaAs layers was investigated on Ge/Si substrates using ultrahigh vacuum chemical vapor deposition. Ga-rich GaAs with anti-site Ga atoms grown at a low V/III ratio was found to suppress the diffusion of Ge into GaAs. S-K mode QD formation was observed on GaAs layers grown on Ge/Si substrates with Ga-rich GaAs initial layers, and improved photoluminescence from 1.3 μm-emitting InAs QDs was demonstrated. 相似文献
5.
Emil V. Jelenković O. Kutsay Shrawan K. Jha K.C. Tam P.F. Lee I. Bello 《Journal of Non》2012,358(4):771-775
In this work, a study of aluminum induced crystallization (AIC) of thin film germanium/silicon/aluminum (Ge/Si/Al) structure on oxidized silicon is presented. The Ge/Si/Al trilayer structure was prepared in three consecutive thin film deposition processes. The AIC was performed in nitrogen at 500 °C within time duration between 1 and 9 h. The progress of crystallization was monitored by optical microscopy, Raman spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM) combined with energy dispersive X-ray spectroscopy (EDS). It was found that in Ge/Si/Al structure the AIC can lead to formation of SiGe alloy at temperature of 500 °C. This presents an alternative low-temperature formation method of SiGe which is suitable for integration with the conventional Si technology in electronic device fabrication. 相似文献
6.
J.Z. Li J. BaiJ.M. Hydrick J.S. ParkC. Major M. CarrollJ.G. Fiorenza A. Lochtefeld 《Journal of Crystal Growth》2009,311(11):3133-3137
Epitaxial GaAs layers have been deposited on polished Ge film grown on exactly (0 0 1) oriented Si substrate by metal-organic chemical vapor deposition (MOCVD) via aspect ratio trapping (ART) method. Double-crystal X-ray diffraction shows that the full-width at half-maximum (FWHM) of the (4 0 0) reflection obtained from 1 μm GaAs is 140 arcsec. Scanning electron microscopy (SEM) of the GaAs layer surface shows that the amount of antiphase domain defects (APD) raised from GaAs/Ge interface using Ge ART on Si is dramatically reduced compared to GaAs layers grown on exact (0 0 1) Ge substrate. Defect reduction and Ge diffusion at vicinal GaAs/Ge interface were investigated via cross-section transmission electron microscopy (X-TEM) and secondary ion mass spectrometry (SIMS). Film morphology and optical properties were evaluated via SEM and room temperature photoluminescence (PL). 相似文献
7.
SiO2/Si/SiO2 single quantum wells (QWs) were prepared under ultrahigh vacuum conditions in order to study their structural, chemical and photoelectrical properties with respect to a possible application in photovoltaic devices. Amorphous silicon (a-Si) layers (thickness <10 nm) were deposited onto quartz glass (SiO2) substrates and subsequently oxidized with neutral atomic oxygen at moderate temperatures of 600 °C. Under these conditions, the formation of suboxides is mostly suppressed and abrupt Si/SiO2 interfaces are obtained. Crystallization of a-Si QWs requires temperatures as high as 1000 °C resulting in a nanocrystalline structure with a small amorphous fraction. The spectral dependence of the internal quantum efficiency of photoconductivity correlates well with the nanocrystalline structure and yields mobility lifetime products of <10?7 cm2 V?1. This rather low value points towards a strong influence of Si/SiO2 interface states on the carrier mobility and the carrier lifetime in Si QWs. Electronic passivation of interface states by subsequent hydrogen treatment in forming gas enhances the internal quantum efficiency by nearly one order of magnitude. 相似文献
8.
Comparative analysis of the specific features of the formation of a dislocation structure in the single-layer epitaxial heterostructures Si1?xGex/Si and Ge1?ySiy/Ge is performed. It is ascertained that, at a relatively low lattice mismatch between an epitaxial layer and a substrate, the sign of misfit strain at the interface significantly affects the processes of defect formation. The most probable reasons for the observed phenomena are analyzed with allowance for the specific features of the state of the ensemble of intrinsic point defects in epitaxial layers subjected to elastic strains of a different sign. 相似文献
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A.M. Pereira C. Magen M.E. Braga R.P. Pinto R. Fermento P.A. Algarabel L. Morellon M.R. Ibarra J.P. Araújo J.B. Sousa 《Journal of Non》2008,354(47-51):5298-5300
We report high resolution measurements of the electrical resistivity (ρ, dρ/dT) and thermopower (S, dS/dT) measurements near the magnetic and structural transition of the layered Tb5Si2Ge2 compound, which are fairly close but not fully coupled. The analysis of the transport properties confirms a split magneto/structural transition, with TS ~ 97 K and TS ~ 107 K for the structural transition (on cooling and heating respectively; 1st-order transition). The magnetic transition occurs only at TC ~ 112 K and without hysteresis (2nd-order transition). The magnetic critical behavior of resistivity is analyzed, obtaining an almost classical mean field exponent (α ~ 0.59) for T > TC. For the structural phase, and below TS, we obtain a rather different exponent (α ~ 1.06). 相似文献
12.
Energy and angular dependent reflectivity measurements of differently prepared SiO2 layers were made in the soft X-ray region in order to study differences in their optical and electronic behaviour caused by the technological process. The optical constants of the layers were determined by fitting the angular dependent reflectivity data with a multilayer model which takes into account the roughness of all interfaces. Detailed knowledge of the polarization level of the primary beam from the synchrotron radiation source is needed for reliable results. The energy dependent reflectivity measurements indicate that high-pressure dry-oxidized layers have a more perfect structure than normal dry-oxidized layers. Independent on the deposition process the Si SiO2 interface roughness amounts to ± 1 nm. The Si2p-XANES of Si and SiO2 were detected. 相似文献
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E.A. Buntov A.F. Zatsepin V.S. Kortov V.A. Pustovarov H.-J. Fitting 《Journal of Non》2011,357(8-9):1977-1980
The paper presents the results of a low-temperature time-resolved photoluminescence (PL) investigation of thin SiO2 films implanted with either oxygen or sulfur ions. Both PL and PLE spectra of the samples demonstrate vibronic oscillations which were attributed to the ground and excited states of sulfur- and oxygen-related molecular species. Vibrational frequencies and anharmonicity parameters calculated from the experimental data agree well with known literature. The most intensive excitation is observed in the spectral region of silica matrix excitons. It is established that such high-energy irradiation leads to non-bridging oxygen hole center creation as well as to the luminescence of molecular species. The results obtained on silica film modification could be of interest for future planar waveguides and thin oxide structure design. 相似文献
15.
J. Kirchhof S. Unger B. Knappe P. Kleinert A. Funke 《Crystal Research and Technology》1987,22(4):495-501
Fluorine incorporation during the deposition of silica layers is studied under MCVD conditions using C2F3Cl3 as fluorine source. The experimental results are compared with known models of the incorporation mechanism. It is found that a gas/solid equilibrium during the consolidation step determines the final fluorine content of the layers. 相似文献
16.
Ge nanocluster formation in SiO2 is of growing interest for new electronic applications. Ion beam synthesis using high‐energy Ge implantation connected with thermal annealing is one possible preparation method of such clusters. In addition to investigations of electrical and structural changes during the cluster formation process we also studied chemical changes in the samples using x‐ray photoelectron spectroscopy (XPS). This was done with low‐energy noble gas ion sputtering for depth profiling. Binding state information one can get from the XPS data by means of factor analysis (FA) in combination with other structural investigations. However, mixed bonding states probably created by ion beam damage during sputter erosion are dominating the results. It is shown, that by changing the experimental conditions (ion beam impact depth during sputtering, electron information depth during XPS measurement) these mixed states are influenced in an appropriate manner. It is concluded that useful chemical information on the behavior of the implanted Ge can be derived despite of the ion beam damage. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
17.
Peng‐Yan Xiao Tie‐Zhen Ren Zhi‐Qiang Wang K. E. Christensen 《Crystal Research and Technology》2010,45(6):589-592
A Si modified Ge10 cluster with structure Na4(Ge,Si)9O20 (denoted as HUT‐1) was synthesized by hydrothermal synthesis at 160 °C with a sodium silicate source. The compound was characterized by single crystal, powder X‐ray diffraction and TGA‐DSC analysis. HUT‐1 crystallizes in space group I41 (80) with calculated unit cell (a=14.966(5) Å, c=7.343(2) Å, V=1644.8(9) Å3), which has the same structure as Na4Ge9O20. HUT‐1 has a high Si/Ge ratio with an approximate formula of Na4Ge7.68Si1.32O20. Single crystal X‐ray structure refinements together with results from X‐ray powder diffraction (XRPD) confirm the occupancy of Si at two tetrahedral sites. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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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
20.
《Journal of Non》2007,353(5-7):703-707
The change of optical and electrical properties of SiO2 layer on Si single crystal exposed to YAG:Nd laser radiation has been found experimentally. The second harmonic of YAG:Nd laser was used as a source of light. Before irradiation the SiO2 layer with thickness 0.75 μm had red color in reflecting light due to the interference. After irradiation with the laser with intensity of more than 3.5 MW/cm2 red color changed to yellow. However, samples with thickness 0.21 μm did not change color after irradiation. We explain such peculiarities of optical properties by change of optical path. Capacity (C) measurements of SiO2 layer with thickness 0.21 μm by the method of capacity–voltage characteristics have shown a decrease of C to more than 40%. It is possible if real part of dielectric permittivity (K) decreases or thickness of the SiO2 layer increases. Atomic force microscope and profilemeter measurements did not show any change of surface roughness for the SiO2 layer with thickness 0.21 μm. We suppose that after irradiation of the SiO2 layer decrease of K takes place due to the formation of nanopores in SiO2 or/and generation of the charged point defect at the interface of Si–SiO2. Particularly the first is in agreement with measurements of micro hardness and capillary effect. 相似文献