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981.
I. Halidou Z. Benzarti Z. Bougrioua T. Boufaden B. El Jani 《Superlattices and Microstructures》2006,40(4-6):490
GaN has been grown using Si/N treatment growth by MOVPE on sapphire (0001) in a home-made vertical reactor. The growth was monitored by in situ laser reflectometry. The morphological, electrical and optical properties of GaN are investigated at all the growth stages. To this aim, the growth was interrupted at different stages. The obtained samples are ex situ characterized by scanning electron microscopy (SEM), room temperature Van der Pauw–Hall electrical transport and low temperature (13 K) photoluminescence (PL) measurements. The SEM images show clearly the coalescence process. A smooth surface is obtained for a fully coalesced layer. During the coalescence process, the electron concentration (n) and mobility (μ) vary from 2×1019 cm−3 to 2×1017 cm−3 and 12 cm2/V s–440 cm2/V s, respectively. The PL maxima shift to higher energy and the FWHM decreases to about 4 meV. A correlation between PL spectra and Hall effect measurements is made. We show that the FWHM follows a n2/3 power law for n above 1018 cm−3. 相似文献
982.
P. Basa P. Petrik M. Fried L. Dobos B. Pcz L. Tth 《Physica E: Low-dimensional Systems and Nanostructures》2007,38(1-2):76
Low-pressure chemical vapour deposited Si3N4/nc-Si/Si3N4 layers prepared on Si substrates were characterized by spectroscopic ellipsometry. Model Dielectric Function (MDF) was applied to obtain the thickness and the dielectric spectra of the middle nc-Si layer. Sensitive effect of the deposition time was obtained on the MDF parameters. A comparison is presented between the studied samples and reference materials. 相似文献
983.
应用群论及原子分子反应静力学方法推导Si分子的电子态及其离解极限,在B3P86/CC-PVTZ水平上,对Si3分子基态进行优化计算,得出Si3基态的单重态能量最低,其稳定构性为的C2V构型,平衡核间距Re=0.2176nm、∠213=79.7°,能量为-869.2057a.u..同时计算出基态的简正振动频率:对称伸缩振动频率ν(B2)=547.6446cm-1,弯曲振动频率ν(A1)=185.6100cm-1和反对称伸缩振动频率ν(A1)=559.6090cm-1.在此基础上,使用多体项展式理论方法,导出了基态Si3分子的全空间解析势能函数,该势能函数准确再现了Si3(C2V)平衡结构. 相似文献
984.
Maximiliano Segala Yuji Takahata Delano P. Chong 《Journal of Electron Spectroscopy and Related Phenomena》2006
Density functional theory (DFT) calculations have been performed on the gas-phase 2p core-electron binding energies (CEBEs) of Si, P, S, Cl, and Ar in 145 cases using the following procedure: ΔEKS (scalar-ZORA + Exc)/TZP//HF/6-31G(d). ΔEKS is the difference in the total Kohn–Sham energies of the 2p-ionized cation and the neutral parent molecule calculated by DFT using different exchange-correlation functionals Exc with triple-zeta polarized basis set, at molecular geometry optimized by HF/6-31G(d), and relativistic effects have been estimated by scalar zeroth-order regular approximation. Among the 26 functionals tested, the form of Exc giving the best overall performance was found to be the combination of OPTX exchange and LYP correlation functionals. For that functional, the average absolute deviation (AAD) of the 145 calculated CEBEs from experiment is 0.26 eV. There are seven other exchange-correlation functionals that led to AADs of less than 0.30 eV. Some functionals give lower AADs than Exc = OPTX-LYP for some individual elements. In the case of Si, for example, the combination of either mPW91-PBE or Becke88-Perdew86 led to an AAD of only 0.10 eV for 56 silicon-containing molecules. Another example is the case of the argon atom, for which the choice of Exc = OPTX-Perdew86 yields a value for CEBE equal to the experimental value. 相似文献
985.
A combination of iterative Jacobsen’s hydrolytic kinetic resolution and reduction of a ketone for the construction of a 1,3-polyol moiety are key steps en route to a total synthesis of (+)-cryptocarya diacetate. 相似文献
986.
O. Jambois A. Vilà J. Carreras B. Garrido G. BenAssayag 《Journal of luminescence》2006,121(2):356-360
The electrical conductivity of silicon oxides containing silicon and silicon-carbon nanoparticles has been investigated. By use of sequential Si+ and C+ ion implantations in silicon oxide followed by an annealing at 1100 °C, luminescent Si nanocrystals and SiC nanoparticles were precipitated. The characterization of the electrical transport has been carried out on two kinds of structures, allowing parallel or perpendicular transport, with respect to the substrate. The first type of samples were elaborated by means of a focus-ion-beam technique: electrical contacts to embedded nanoparticles were made by milling two nanotrenches on the sample surface until reaching the buried layer, then filling them with tungsten. The distance between the electrodes is about 100 nm. The second type of samples correspond to 40 nm thick typical MOS capacitors.The electron transport along the buried layer has shown a dramatic lowering of the electrical current, up to five orders of magnitude, when applying a sequence of voltages. It has been related to a progressive charge retention inside the nanoparticles, which, on its turn, suppresses the electrical conduction along the layer. On the other hand, the MOS capacitors show a reversible carrier charge and discharge effect that limits the current at low voltage, mostly due to the presence of C in the layers. A typical Fowler-Nordheim injection takes place at higher applied voltages, with a threshold voltage equal to 23 V. 相似文献
987.
E. Vasco 《Surface science》2005,575(3):247-259
The surface relaxation mechanisms governing the preferential adsorption of metal atoms onto the faulted half-cells of a 7 × 7 reconstructed Si(1 1 1) surface are studied by rate equations and kinetic Monte Carlo simulations. The versatility of these mechanisms to control the formation of quasi-perfect 2D arrays of metal clusters is revealed via the optimization of the deposition/annealing conditions as a function of operating mechanisms, the Si(1 1 1)7 × 7 energy landscape, and the thermal stability of the created clusters. The influence on the formation process of such nanoarrays of the balance between kinetic limitations, which are especially relevant on Si(1 1 1)7 × 7, and thermodynamic tendencies is discussed. 相似文献
988.
以硝酸镍溶液为化学源,对于用不同方法沉积得到的非晶硅膜作晶化前驱物,都能予以不同程度的晶化.用VHF-PECVD方法获得的非晶硅膜作前驱物,易于去氢并更容易晶化.当化学源浓度不同时,晶化效果会存在一定差别,在一定的范围内,溶液浓度越高,晶化后形成的晶粒越大.退火气氛对晶化结果产生某些影响,可以发现,在N2气氛下退火,比在大气下有更好的晶化效果.最后对物理源与化学源作诱导金属的晶化结果进行了比较,结果表明,对诱导金属源而言,化学源显示出更为有效的晶化趋势.
关键词:
金属诱导晶化
多晶硅薄膜
低温制备
退火处理 相似文献
989.
Si K-edge XAFS was used to characterize a stoichiometric SiC film prepared by pulsed KrF laser deposition. The film was deposited on a p-type Si(1 0 0) wafer at a substrate temperature of 250 °C in high vacuum with a laser fluence of ∼5 J/cm2. The results reveal that the film contains mainly a SiC phase with an amorphous structure in which the Si atoms are bonded to C atoms in its first shell similar to that of crystalline SiC powder but with significant disorder. 相似文献
990.
Hong Wang Wen-cai Lu Ze-sheng Li Chia-chung Sun 《Journal of Molecular Structure》2005,730(1-3):263-271
Ab initio calculations are carried out to study the adsorption of Lithium atom on the Sin cluster with n ranging from 2 to 7. At the MP2/6-31G(d) level, the structures of the neutral Sin clusters and the SinLi clusters (n=2–7) are optimized. The single-point energy at QCISD/6-311+G(d,p) level for the optimized isomers are further performed. Harmonic vibrational frequency analysis at the MP2/6-31G(d) level is also undertaken to confirm that the optimize geometries are stable. Based on our results, the most favorable sites for Li adsorption on the Si2–7 clusters are the bridge sites. In addition, the vertical ionization energies of the SinLi clusters and the electron affinities of the Sin clusters are also calculated. The clear parallelism between the vertical ionization energies of SinLi and the electron affinities of Sin is found. This is consistent with the fact that the framework of the Sin in the SinLi cluster is similar to the structure of the corresponding negative ion . 相似文献