共查询到20条相似文献,搜索用时 15 毫秒
1.
Rao Huang Li-bo Ma Jian-ping Ye Yong-qian Wang Ze-xian Cao 《Frontiers of Physics in China》2008,3(2):173-180
High-density silicon nanoparticles with well-controlled sizes were grown onto cold substrates in amorphous SiN
x
and SiC matrices by plasma-enhanced chemical vapor deposition. Strong, tunable photoluminescence across the whole visible
light range has been measured at room temperature from such samples without invoking any post-treatment, and the spectral
features can find a qualitative explanation in the framework of quantum confinement effect. Moreover, the decay time was for
the first time brought down to within one nanosecond. These excellent features make the silicon nanostructures discussed here
very promising candidates for light-emitting units in photonic and optoelectronic applications.
相似文献
2.
High-density silicon nanoparticles with well-controlled sizes were grown onto cold substrates in amorphous SiNx and SiC matrices by plasma-enhanced chemical vapor deposition. Strong, tunable photoluminescence across the whole visible light range has been measured at room temperature from such samples without invoking any post-treatment, and the spectral features can find a qualitative explanation in the framework of quantum confinement effect. Moreover, the decay time was for the first time brought down to within one nanosecond. These excellent features make the silicon nanostructures discussed here very promising candidates for light-emitting units in photonic and optoelectronic applications. 相似文献
3.
A laboratory setup for fabrication of amorphous silicon thin films and structures on their basis by chemical vapor deposition (CVD) has been developed and assembled. All the operating processes were automated by software in LabVIEW media. Special programs and subprograms were created to maintain the corresponding temperature with a necessary accuracy, to control the gas flow controller, as well as to control the vacuum valves. Hydrogenated amorphous silicon thin films of n-, p- and i-types, as well as a test p-i-n structures with different thicknesses were made. Transmission and photoconductivity spectra of the obtained samples were investigated. 相似文献
4.
Z. Jiang T. Xie X.Y. Yuan B.Y. Geng G.S. Wu G.Z. Wang G.W. Meng L.D. Zhang 《Applied Physics A: Materials Science & Processing》2005,81(3):477-479
A large quantity of nanowires and nanotubes of silicon oxide are produced by using Fe–Co–Ni alloy nanoparticles as catalyst. The products have a uniform diameter of around 100 nm. The nanowires have a smooth surface and the lengths are up to 100 μm or more. A new morphology called a serrated joint nanotube was found. The alloy catalyst plays a key role in the synthesis process. Room-temperature photoluminescence measurement under excitation at 360 nm showed that the silicon oxide had a strong blue-green emission at 525 nm (about 2.36 eV), which may be related to oxygen defects. PACS 81.15.Gh; 81.07.Vb; 81.07.De; 42.70.Nq; 78.55.-m 相似文献
5.
K. Giannakopoulos N. Boukos A. Travlos T. Monteiro M.J. Soares M. Peres A. Neves M.C. Carmo 《Applied Physics A: Materials Science & Processing》2007,88(1):41-44
Isolated, self assembled ZnO nanoparticles are grown in two steps: by the electron beam evaporation of Zn on oxidised silicon
wafers, during which isolated Zn nanodots are grown, and a subsequent annealing in oxygen that results in the desired ZnO
nanodots. Low temperature PL measurements of the ZnO nanodots show that the near band edge part of the spectra is dominated
by a zero phonon line near 3.36 eV which is an overlap of two emitting lines near 3.363 eV and 3.367 eV. Characterization
by TEM and EELS shows that the nanoparticles are zinc oxide single crystals grown with their c-axis perpendicular to the substrate;
their distribution, size and crystallinity depend on the deposition parameters of zinc and the growth substrate. We discuss
the effect of these parameters on the morphology of the resulting material. Our approach demonstrates a simple method for
the growth of high purity isolated ZnO nanodots of similar sizes, distributed uniformly on a large surface.
PACS 61.46.Df; 81.05.Dz; 81.07.-b 相似文献
6.
Noriaki Tsurumachi Chang-Sik Son Tae Geun Kim Kazunori Hikosaka Kazuhiro Komori Mutsuo Ogura 《Physica E: Low-dimensional Systems and Nanostructures》2004,21(2-4):300
We investigated the temperature dependence of the time-resolved photoluminescence (PL) spectra of high-density InGaAs/AlGaAs quantum wire (QWR) distributed-feedback laser structure on a submicron grating. A red-shift of peak in the time-resolved PL after photo-excitation was observed due to the relaxation of the photo-generated excitons from the entire QWR to localized centers at 10 K. On the other hand, at 60 K, no red-shift in the time-resolved PL spectra was observed since the localization centers are thermally activated and the excitons are delocalized. 相似文献
7.
The polarization method of photomagnetoelectric investigation was used for determining values of refractive indexes of SiO2 surface layers. This method of investigation is complementary to ellipsometry. It is based on measurements of intensity of variously polarized radiation which enters semiconductor sample through the investigated surface layer. The SiO2 layers were obtained by thermal oxidation of 〈111〉 and 〈100〉 oriented silicon in different gases 相似文献
8.
J. Richter J. Meinertz J. Ihlemann 《Applied Physics A: Materials Science & Processing》2011,104(3):759-764
UV-absorbing silicon monoxide (SiO
x
, x≈1) thin films on fused silica substrates are irradiated by an ArF excimer laser (wavelength 193 nm) in the sub-ablation threshold
regime. Multi-pulse irradiation of films with ∼200-nm thickness at a fluence of about 100 mJ/cm2 leads to a significant increase of the UV transmission, indicating the oxidation of SiO
x
to SiO2. The quality of the obtained films after this laser annealing process depends on the oxygen content of the environment. Irradiation in air at atmospheric pressure leads to the formation of sub-micron-sized
oxide particles on top of the film. Structured illumination is applied either to form areas of the film with changed transmission
and refractive index, or for the formation of regular particle patterns with sub-micron periods. These processes can be utilized
for the fabrication of phase masks or for various types of surface functionalization. 相似文献
9.
J. Sládková 《Czechoslovak Journal of Physics》1963,13(6):452-458
The optical constants of oxide films formed by heating single-crystal silicon specimens were measured. The measurements were carried out in a range of 300° to 1000°C. The thickness and refractive indices of the oxide films were determined by the polarimetric method. In the measured temperature interval the oxidation process can be divided into three groups. In the first range, from 300° to 560°C, no oxidation of the silicon surface was observed. In the second interval, from 560° to 950°C, the oxidation of silicon proceeded according to the linear oxidation law. At temperatures from 950° to 1000°C the thickness of the oxide films increased with the square root of the heating time according to the parabolic oxidation law. 相似文献
10.
L. K. Orlov E. A. Shteinman N. L. Ivina V. I. Vdovin 《Physics of the Solid State》2011,53(9):1798-1805
The light-emitting properties of cubic silicon carbide films grown by vacuum vapor phase epitaxy on Si(100) and Si(111) substrates
under conditions of decreased growth temperatures (T
gr ∼ 900–700°C) have been discussed. Structural investigations have revealed a nanocrystalline structure and, simultaneously,
a homogeneity of the phase composition of the grown 3C-SiC films. Photoluminescence spectra of these structures under excitation of the electronic subsystem by a helium-cadmium
laser (λexcit = 325 nm) are characterized by a rather intense luminescence band with the maximum shifted toward the ultraviolet (∼3 eV)
region of the spectral range. It has been found that the integral curve of photoluminescence at low temperatures of measurements
is split into a set of Lorentzian components. The correlation between these components and the specific features of the crystal
structure of the grown silicon carbide layers has been analyzed. 相似文献
11.
V. Godinho V.N. Denisov B.N. Mavrin N.N. Novikova E.A. Vinogradov V.A. Yakovlev C. Fernndez-Ramos M.C. Jimnez de Haro A. Fernndez 《Applied Surface Science》2009,256(1):156-164
Vibrational (infrared and Raman) spectroscopy has been used to characterize SiOxNy and SiOx films prepared by magnetron sputtering on steel and silicon substrates. Interference bands in the infrared reflectivity measurements provided the film thickness and the dielectric function of the films. Vibrational modes bands were obtained both from infrared and Raman spectra providing useful information on the bonding structure and the microstructure (formation of nano-voids in some coatings) for these amorphous (or nanocrystalline) coatings. X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) analysis have also been carried out to determine the composition and texture of the films, and to correlate these data with the vibrational spectroscopy studies. The angular dependence of the reflectivity spectra provides the dispersion of vibrational and interference polaritons modes, what allows to separate these two types of bands especially in the frequency regions where overlaps/resonances occurred. Finally the attenuated total reflection Fourier transform infrared measurements have been also carried out demonstrating the feasibility and high sensitivity of the technique. Comparison of the spectra of the SiOxNy films prepared in various conditions demonstrates how films can be prepared from pure silicon oxide to silicon oxynitride with reduced oxygen content. 相似文献
12.
E. A. Tutov 《Technical Physics》2012,57(6):765-769
The electrophysical parameters of ovalbumin/silicon and propolis/silicon heterostructures are studied using impedance spectroscopy and high-frequency capacitance-voltage characteristics under water vapor sorption conditions. 相似文献
13.
Cathodoluminescence (CL) spectra for the Si nanocrystallites embedded in a matrix of silicon oxide films are measured at room temperature. The CL spectra consist of two principal bands whose peak energies are in a near-infrared (NIR) region (<1.6 eV) and in a blue region (2.6 eV), respectively. The spectral feature of the NIR CL band is similar to the corresponding PL spectra. The strong correlation between the presence of Si nanocrystallites and the formation of the NIR CL band are found as well as the PL spectrum. The peak energy of the blue CL band is slightly lower than that of the luminescence band originating from oxygen vacancies (≡Si–Si≡) in SiO2. Therefore, the blue CL band is considered to come from Sin clusters with n3 in the oxide matrix. Under irradiation of electron beams, degradation of the intensity is observed for both the CL bands but the decay characteristics are different. 相似文献
14.
Amorphous silicon oxide thin films were prepared by co-evaporation of Si and SiO in ultra-high vacuum. Different compositions were obtained by changing the evaporation rate of silicon. After thermal annealing treatments, the dissociation of the silicon oxide in pure silicon and silicon dioxide leads to the formation of silicon clusters embedded in a silicon oxide matrix. Thus the samples were annealed to different temperatures up to 950°C. Depending on the annealing temperature and on the composition, different cluster sizes were obtained. The photoluminescence (PL) energy depends on the cluster size and a large range of wavelengths is obtained from 500 to 750 nm. The PL, attributed to a confinement effect of the electron–hole pairs in the silicon particles, is studied as a function of the temperature. It is demonstrated that the continuous decrease of PL intensity with the temperature from 77 to 500 K depends on the structure of the samples. For samples with well-separated clusters, the PL decreases rapidly with the temperature. For samples containing clusters separated by a small distance, the PL weakly depends on the temperature. No shift of the energy is observed. The results are discussed by taking into account the competition between the radiative recombination in the silicon clusters and the non-radiative escape of the carriers via a hopping mechanism. 相似文献
15.
Photoluminescence (PL) properties of Er-doped silicon rich oxide thin films deposited on Si substrate by co-evaporation of silicon monoxide and Er under different atmospheres are investigated. The samples exhibit luminescence peak at 1.54 μm which could be assigned to the recombination in intra-4f Er3+ transition. PL shows that this transition is highest when ammonia atmosphere is used during deposition followed by an annealing temperature at 850 °C in 95% N2+5% H2 gas (forming gas). In fact, we believe that the presence of the N atoms around Er ions increases the intensity of the 1.54 μm luminescence. 相似文献
16.
A. E. Aleksenskii P. N. Brunkov A. T. Dideikin D. A. Kirilenko Yu. V. Kudashova D. A. Sakseev V. A. Sevryuk M. S. Shestakov 《Technical Physics》2013,58(11):1614-1618
A method is proposed to produce large-area single-layer graphene oxide films on the surface of semiconductor silicon wafers by precipitation from aqueous suspensions. Graphene oxide is synthesized from natural crystalline graphite during chemical oxidation and represents a wide-gap insulator. Single-layer graphene with a homogeneous-fragment size up to 50 μm can be formed by the reduction of graphene oxide films, and this size is significantly larger than those achieved to date. 相似文献
17.
D. Valerini A.P. Caricato M. Lomascolo A. Taurino M. Martino 《Applied Surface Science》2009,255(24):9680-9683
Zinc oxide films with different morphologies have been grown by pulsed laser deposition, varying substrate temperature and oxygen pressure. At low oxygen pressure and low substrate temperature continuous films with different roughness have been obtained, while at high substrate temperature a film with sparse hexagonal pyramids has been observed. Increasing the oxygen pressure the film became rougher and at 100 Pa a rod-array has been deposited. The columns of this rod-array grew along the wurtzite c-axis perpendicularly to the substrate surface as proved by X-ray diffraction measurements. Near to the sample borders the columns were slightly tilted towards the center of the sample. The possible growth mechanisms giving rise to the different morphologies have been discussed. Low-temperature photoluminescence measurements allowed to get information about the film quality, showing the variations of the excitonic peak and two defect bands (green and violet-blue) with the different deposition parameters. 相似文献
18.
Cobalt oxide thin films were prepared by a facile spray pyrolysis technique, using a perfume atomizer with an aqueous solution of hydrated cobalt chloride salt with a molar concentration of 0.025?M as a source of cobalt. The films were deposited onto glass substrates at temperature of 350?°C. The structural, morphological, and electrochromic properties of the obtained films were studied. It was found from X-ray diffraction analysis that the films were polycrystalline in nature with spinel-type cubic structure and preferred orientation along [111] direction. The Scanning Electron Microscopy images revealed a porous structure with the average grain size around 200?nm. The cyclic voltammetry measurements revealed that Cobalt oxide thin film is an anodically coloring electrochromic material with a transmittance variation in the visible range of 31%, and a fast response time (about 2?seconds) and a good cycling stability. These electrochromic performances make cobalt oxide thin film an attractive material for using as an anodic electrochromic material in smart windows devices. The photoluminescence spectra exhibited a strong emission in the visible region confirming the good crystallinity properties of Co3O4 thin films. 相似文献
19.
A. Benami G. Santana B.M. Monroy A. Ortiz J.C. Alonso J. Fandio J. Aguilar-Hernndez G. Contreras-Puente 《Physica E: Low-dimensional Systems and Nanostructures》2007,38(1-2):148
The photoluminescence (PL) of silicon nanoclusters embedded in silicon nitride films grown by remote plasma-enhanced chemical vapor deposition at 200 °C, using mixtures of SiCl4/H2/Ar/NH3 is investigated. It was found that the color and the intensity of the PL of the as-grown samples depend on the H2 flow rate, and there is an optimum flow for which a maximum luminescence is obtained. A strong improvement of the PL intensity and change in color was obtained with annealing treatments in the range of 500–1000 °C. The changes in the composition, structure and optical properties of the films, as a function of H2 flow rate and thermal treatments, were studied by means of Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, ellipsometry and ultraviolet–visible transmission measurements. We conclude that the PL can be attributed to quantum confinement effect in silicon nanoclusters embedded in silicon nitride matrix, which is improved when a better passivation of the nanoclusters surface is obtained. 相似文献
20.
Silicon suboxide thin films have been fabricated by physical vapor deposition of silicon monoxide in vacuum at controlled
oxygen partial pressure. These films undergo a phase separation into silicon- and oxygen-enriched regions upon thermal processing.
At temperatures around 900 °C, the onset of Si nanocrystallite formation is observed, regardless of film stoichiometry. With
increasing initial oxygen content of the films, the mean size of created nanocrystallites decreases whereas the corresponding
photoluminescence emission blueshifts. The photoluminescence intensity increases with increasing annealing temperature up
to 1050 °C. Upon resonant excitation at low temperatures, the photoluminescence exhibits phonon replica signature. Therefore,
the emission may be attributed to excitonic recombination in the nanocrystallites.
Received: 3 July 2001 / Accepted: 6 August 2001 / Published online: 17 October 2001 相似文献