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1.
Thin films of crystalline lithium niobate (LN) grown on Si(1 0 0) and SiO 2 substrates by electron cyclotron resonance plasma sputtering exhibit distinct interfacial structures that strongly affect the orientation of respective films. Growth at 460–600 °C on the Si(1 0 0) surface produced columnar domains of LiNbO 3 with well-oriented c-axes, i.e., normal to the surface. When the SiO 2 substrate was similarly exposed to plasma at temperatures above 500 °C, however, increased diffusion of Li and Nb atoms into the SiO 2 film was seen and this led to an LN–SiO 2 alloy interface in which crystal-axis orientations were randomized. This problem was solved by solid-phase crystallization of the deposited film of amorphous LN; the degree of c-axis orientation was then immune to the choice of substrate material. 相似文献
2.
Segregation phenomenon of Ga in Czochralski (CZ)–Si crystal growth has been investigated. The effective segregation coefficient, keff, of Ga was obtained for different growth rates by assuming the simple relationship between the concentration of Ga in Si crystal and the bulk Ga concentration in melt. Applying BPS theory to effective segregation coefficients which is valid for the melt-solidified fraction up to 0.38, an equilibrium segregation coefficient of Ga was obtained, k0=0.0079. 相似文献
3.
The structure and thermal stability of ZrO 2 films grown on Si (1 0 0) substrates by metalorganic chemical vapor deposition have been studied by high-resolution transmission electron microscopy, selected area electron diffraction and X-ray energy dispersive spectroscopy. As-deposited films consist of tetragonal ZrO 2 nanocrystallites and an amorphous Zr silicate interfacial layer. After annealing at 850°C, some monoclinic phase is formed, and the grain size is increased. Annealing a 6 nm thick film at 850°C in O 2 revealed that the growth of the interfacial layer is at the expense of the ZrO 2 layer. In a 3.0 nm thick Zr silicate interfacial layer, there is a 0.9 nm Zr-free SiO 2 region right above the Si substrate. These observations suggest that oxygen reacted with the Si substrate to grow SiO 2, and SiO 2 reacted with ZrO 2 to form a Zr silicate interfacial layer during the deposition and annealing. Oxygen diffusion through the tetragonal ZrO 2 phase was found to be relatively easier than through the monoclinic phase. 相似文献
4.
Deposition of sub-monolayer silicon on SiO 2/Si(1 0 0) greatly facilitates nucleation in subsequent thermal chemical vapor deposition (CVD) of silicon nanoparticles. Sub-monolayer seeding is accomplished using silicon atoms generated via disilane decomposition over a hot tungsten filament. The hot-wire process is nonselective towards deposition on silicon and SiO 2, is insensitive to surface temperature below 825 K, and gives controlled coverages well below 1 ML. Thermal CVD of nanoparticles at 1×10 −4 Torr disilane and temperatures ranging from 825 to 925 K was studied over SiO 2/Si(1 0 0) surfaces that had been subjected to predeposition of Si or were bare. Seeding of the SiO 2 surface with as little as 0.01 ML is shown to double the nanoparticle density at 825 K, and densities are increased twenty fold at 875 K after seeding the surface with 30% of a monolayer. 相似文献
5.
Homogeneous and transparent V 2O 5–TiO 2 composite nanometer thin films were prepared on glass substrates by sol–gel processing and dip-coating technique. The films as well as the dried powder of bulk gel were characterized by different techniques like X-ray diffraction (XRD), high-resolution scanning electron microscopy (HRSEM), atomic force microscope (AFM) and thermogravimetry–differential thermal analysis (TG–DTA). The hydrophilicity of the films was determined by measuring the water contact angles on the films. The results showed that the dopant of V 2O 5 on TiO 2 thin films could produce a visible-light response to the films, and the introduction of V 2O 5 could suppress the structural phase transition and crystal growth of TiO 2 crystal. Finally, the relationship between crystalline size and hydrophilicity under sunlight was investigated in this article. 相似文献
6.
Sessile drop experiments were performed on molten indium antimonide on clean quartz (fused silica) surfaces. A cell was constructed through which argon, helium, oxygen, hydrogen or a mixture of these was flowed at 600 °C. Some of the InSb was doped with 0.1% Ga. The surface tension σ of oxide-free molten InSb was smaller in Ar than in He, may have increased with increasing O 2 in the gas, and was not influenced by Ga or H 2. The contact angle θ on silica was higher in the presence of Ar, was lowered by O 2, and was not influenced by H 2 or Ga. The work of adhesion W and the surface energy σsv of the silica were higher in He than in Ar. The surface remained free of solid oxide only in flowing gas containing 0.8 ppm O 2. This behavior is attributed to reaction of O 2 at the surface of the melt to form In 2O gas. When solid oxide formed on Ga-doped material, it was strongly enriched in Ga, with the Ga/In ratio increasing with the concentration of O 2 in the gas. Examination of published sessile-drop results for liquid metals and semiconductors on silica revealed that W and σsv were highest for reactive melts, in which SiO2 dissolves. For non-reactive melts, W and σsv were lower and θ higher in a gas than in a vacuum, regardless of whether the experiments had been carried out in sealed ampoules, a flowing gas, or dynamic vacuum. The implication is that the surface of silica was different in a vacuum than in a gas at 1 bar. 相似文献
7.
The (Pb 0.90La 0.10)TiO 3 [PLT] thick films (3.0 μm) with a PbO buffer layer were deposited on the Pt(1 1 1)/Ti/SiO 2/Si(1 0 0) substrates by RF magnetron sputtering method. The PLT thick films comprise five periodicities, the layer thicknesses of (Pb 0.90La 0.10)TiO 3 and PbO in one periodicity are fixed. The PbO buffer layer improves the phase purity and electrical properties of the PLT thick films. The microstructure and electrical properties of the PLT thick films with a PbO buffer layer were studied. The PLT thick films with a PbO buffer layer possess good electrical properties with the remnant polarization ( Pr=2.40 μC cm −2), coercive field ( Ec=18.2 kV cm −1), dielectric constant ( εr=139) and dielectric loss (tan δ=0.0206) at 1 kHz, and pyroelectric coefficient (9.20×10 −9 C cm −2 K −1). The result shows the PLT thick film with a PbO buffer layer is a good candidate for pyroelectric detector. 相似文献
8.
The segregation of Ga during the growth of Czochralski-Si crystals with Ge codoping was investigated. The effective segregation coefficient of Ga in Ga/Ge-codoped Si crystal growth was nearly constant over a wide Ge concentration range, even at high Ge concentrations of about 10 21 cm −3. In contrast, the effective segregation coefficient increased at high B concentrations in Ga/B-codoped CZ-Si crystal growth. The segregation behavior of Ga in Ga/Ge- and Ga/B-codoped CZ-Si crystal growth was theoretically compared. The difference in the segregation coefficients of Ga as a function of the codoped impurity (Ge or B) between the two Si crystals was attributed to a difference in the excess enthalpy due to impurity incorporation into the Si crystal between Ga–Ge pairs and Ga–B pairs 相似文献
9.
在石墨烯的化学气相沉积工艺中,铜箔是决定石墨烯薄膜质量的重要因素。传统铜箔由于制备工艺的限制,存在大量的缺陷,导致石墨烯薄膜的成核密度较高。本工作选用抛光铝板、抛光不锈钢板、微晶玻璃和SiO 2/Si作为基材,用热蒸镀法制备了不同粗糙度的铜箔,并详细讨论了以该系列铜箔生长高平整度石墨烯薄膜的条件及铜箔对石墨烯薄膜品质的影响。实验结果表明,铜箔以(111)取向为主,与基材分离后,表面具有纳米级平整度。在生长石墨烯后,从SiO 2/Si剥离的铜箔成核密度是4种基材中最小的。同时,从SiO 2/Si剥离的铜箔晶体结构变化最不明显,具有良好的结晶性,表面几乎不存在铜晶界缺陷。当压强为3 000 Pa,氢气和甲烷流速分别为300 mL/min和0.5 mL/min时,可以获得约1 mm横向尺寸的石墨烯单晶晶畴。 相似文献
10.
本文对TOPCon电池发射结的叠层钝化膜进行了研究,对比了3种不同叠层钝化膜(SiO 2/SiN x、Al 2O 3(1.5 nm)/SiN x、SiO 2/Al 2O 3(1.5 nm)/SiN x)的钝化性能。结果表明:Al 2O 3(1.5 nm)/SiN x的钝化性能优于SiO 2/SiN x,SiO 2/Al 2O 3(1.5 nm)/SiN x的钝化水平最佳,隐开路电压均值可达到705 mV。基于Al 2O 3/SiN x叠层膜研究了Al 2O 3厚度(1.5 nm、3 nm和5 nm)对钝化性能和电池转换效率的影响。当Al 2O 3厚度由1.5 nm增加到3 nm时,钝化性能得到明显提升,隐开路电压均值提高了20 mV,达到707 mV,对应电池的光电转换效率升高了0.23个百分点,与SiO 2/Al 2O 3(1.5 nm)/SiN x叠层膜电池的转换效率持平。然而,当Al 2O 3厚度继续增加至5 nm时,隐开路电压均值保持不变。因此可以使用Al 2O 3(3 nm)/SiN x叠层膜代替SiO 2/Al 2O 3(1.5 nm)/SiN x叠层膜,不仅简化了电池的工艺步骤,而且降低了生产成本。 相似文献
11.
We have investigated photoluminescence (PL) and electron Hall mobility for unintentionally doped GaN epitaxial layers grown by low-pressure metalorganic chemical vapor deposition on c-plane Al 2O 3 substrates. Four GaN films having identical dislocation density but remarkably different electron Hall mobility were exploited. At low temperature (12 K), a PL line associated with a bound exciton was observed and strong correlations were found between the Hall mobility and the PL intensity of the exciton transition. That is, relative PL intensity of the bound exciton to a donor-bound exciton monotonously increased with decreasing the electron mobility of the GaN films. This correlation was interpreted in terms of electrical compensation. Efforts to find the chemical origin of the PL line led to the conclusion that the BE line originated neither from threading dislocations nor from extrinsic point defects. Intrinsic acceptors such as Ga vacancy and GaN anti-site were suspected as plausible origin. 相似文献
12.
We have studied the impact of several Si selective epitaxial growth (SEG) process on the agglomeration of ultra-thin, patterned silicon-on-insulator (SOI) layers. Through a careful analysis of the effects of the in situ H 2 bake temperature (that followed an ex situ “HF-last” wet cleaning) and of the silicon growth temperature on the SOI film quality, we have been able to develop a low-temperature SEG process that allows the growth of Si on patterned SOI layers as thin as 3.4 nm without any agglomeration or Si moat recess at the Si window/shallow trench isolation edges. This process consists of an in situ H 2 bake at 650 °C for 2 min, followed by a ramping-up of the temperature to 750 °C, then some SEG of Si at 750 °C using a chlorinated chemistry (i.e. SiH 2Cl 2+HCl). 相似文献
13.
Nucleation and growth of wurtzite AlN layers on nominal and off-axis Si(0 0 1) substrates by plasma-assisted molecular beam epitaxy is reported. The nucleation and the growth dynamics have been studied in situ by reflection high-energy electron diffraction. For the films grown on the nominal Si(0 0 1) surface, cross-sectional transmission electron microscopy and X-ray diffraction investigations revealed a two-domain film structure (AlN 1 and AlN 2) with an epitaxial orientation relationship of [0 0 0 1] AlN || [0 0 1] Si and
AlN 1 ||
AlN 2 || [1 1 0] Si. The epitaxial growth of single crystalline wurtzite AlN thin films has been achieved on off-axis Si(0 0 1) substrates with an epitaxial orientation relationship of [0 0 0 1] AlN parallel to the surface normal and 0 1 1 0 AlN || [1 1 0] Si. 相似文献
14.
The growth of ZnO single crystals and crystalline films by solvothermal techniques is reviewed. Largest ZnO crystals of 3 inch in diameter are grown by a high-pressure medium-temperature hydrothermal process employing alkaline-metal mineralizer for solubility enhancement. Structural, thermal, optical and electrical properties, impurities and annealing effects as well as machining are discussed. Poly- and single-crystalline ZnO films are fabricated from aqueous and non-aqueous solutions on a variety of substrates like glass, (100) silicon, -Al 2O 3, Mg 2AlO 4, ScAlMgO 4, ZnO and even some plastics at temperatures as low as 50 °C and ambient air conditions. Film thickness from a few nanometers up to some tens of micrometers is achieved. Lateral epitaxial overgrowth of thick ZnO films on Mg 2AlO 4 from aqueous solution at 90 °C was recently developed. The best crystallinity with a full-width half-maximum from the (0002) reflection of 26 arcsec has been obtained by liquid phase epitaxy employing alkaline-metal chlorides as solvent. Doping behavior (Cu, Ga, In, Ge) and the formation of solid solutions with MgO and CdO are reported. Photoluminescence and radioluminescence are discussed. 相似文献
15.
It is demonstrated that the NEXAFS spectra are a “fingerprint” of the symmetry and the composition of the binary nitrides GaN, AlN and InN, as well as of their ternary alloys In 0.16Ga 0.84N and Al yGa 1−yN. From the angular dependence of the N-K-edge NEXAFS spectra, the hexagonal symmetry of the under study compounds is deduced and the (p x, p y) or p z character of the final state is identified. The energy position of the absorption edge ( Eabs) of the binary compounds GaN, AlN and InN is found to red-shift linearly with the atomic number of the cation. The Eabs of the Al yGa 1−yN alloys takes values in between those corresponding to the parent compounds AlN and GaN. Contrary to that, the Eabs of In 0.16Ga 0.84N is red-shifted relative to that of GaN and InN, probably due to ordering and/or phase separation phenomena. The EXAFS analysis results reveal that the first nearest-neighbour shell around the N atom, which consists of Ga atoms, is distorted in both GaN and Al xGa 1−xN for x<0.5. 相似文献
16.
We investigated the dependence of the Y 2O 3 film growth on Si surface at initial growth stage. The reflection high-energy electron diffraction, X-ray scattering, and atomic force microscopy showed that the film crystallinity and morphology strongly depended on whether Si surface contained O or not. In particular, the films grown on oxidized surfaces revealed significant improvement in crystallinity and surface smoothness. A well-ordered atomic structure of Y 2O 3 film was formed on 1.5 nm thick SiO 2 layer with the surface and interfacial roughness markedly enhanced, compared with the film grown on the clean Si surfaces. The epitaxial film on the oxidized Si surface exhibited extremely small mosaic structures at interface, while the film on the clean Si surface displayed an island-like growth with large mosaic structures. The nucleation sites for Y 2O 3 were provided by the reaction between SiO 2 and Y at the initial growth stage. The SiO 2 layer known to hinder crystal growth is found to enhance the nucleation of Y 2O 3, and provides a stable buffer layer against the silicide formation. Thus, the formation of the initial SiO 2 layer is the key to the high-quality epitaxial growth of Y 2O 3 on Si. 相似文献
17.
Effects of relaxation of interfacial misfit strain and non-stoichiometry on surface morphology and surface and interfacial structures of epitaxial SrTiO 3 (STO) thin films on (0 0 1) Si during initial growth by molecular beam epitaxy (MBE) were investigated. In situ reflection high-energy electron diffraction (RHEED) in combination with X-ray diffraction (XRD), atomic force microscopy (AFM), X-ray photoelectron spectrometry (XPS) and transmission electron microscopy (TEM) techniques were employed. Relaxation of the interfacial misfit strain between STO and Si as measured by in situ RHEED indicates initial growth is not pseudomorphic, and the interfacial misfit strain is relaxed during and immediately after the first monolayer (ML) deposition. The interfacial strain up to 15 ML results from thermal mismatch strain rather than lattice mismatch strain. Stoichiometry of STO affects not only surface morphology but interfacial structure. We have identified a nanoscale Sr 4Ti 3O 10 second phase at the STO/Si interface in a Sr-rich film. 相似文献
18.
We have fabricated LaNiO 3 and BaTiO 3 films using the rf sputtering method. The LaNiO 3 were deposited on Si substrates, demonstrating a (1 0 0) highly oriented structure and nanocrystalline characteristic with a grain size of 30 nm. The BaTiO 3 thin films were deposited on the LaNiO 3 buffer layers, and have exhibited a (1 0 0) texture with a thickness of 400 nm. A smooth interface is obtained between the LaNiO 3 bottom electrode and the BaTiO 3 film from cross-section observations by scanning electron microscopy. The bi-layer films show a dense and column microstructure with a grain size of 60 nm. Ferroelectric characterizations have been obtained for the BaTiO 3 films. The remnant polarization and coercive field are 2.1 μC/cm 2 and 45 kV/cm, respectively. The leak current measurements have shown a good insulating property. 相似文献
19.
An EXAFS study has been made on the structure of three composition ranges of Ce---Si---O amorphous thin films prepared by RF sputtering. The measurements, carried out on the K edge of silicon and the L 3 edge of cerium, reveal that in the stoichiometric oxygen films of the general formula (Ce, Si) O 2, both cerium and silicon are four-coordinated by oxygen regardless of the O : Si ratio. In the oxygen-deficient films cerium remains four-coordinated by oxygen, but, around silicon, the oxygen atoms are progressively replaced by silicon as the oxygen content of the films is reduced. In silicon-rich films which are very deficient in oxygen, the oxygen atoms prefer to ramain coordinated with cerium, rather than silicon. A definite decrease in the Si---O distance with increase in Si---O coordination has been found. The effect is attributed to an increase in the charge of silicon with oxygen coordination, and supports a randomly bonded model for the structure. The total oxygen coordination, derived from a consideration of bond conservation, indicates that the film structures are probably SiO2-type continuous random networks. 相似文献
20.
Multi-domained heteroepitaxial rutile-phase TiO 2 (1 0 0)-oriented films were grown on Si (1 0 0) substrates by using a 30-nm-thick BaF 2 (1 1 1) buffer layer at the TiO 2–Si interface. The 50 nm TiO 2 films were grown by electron cyclotron resonance oxygen plasma-assisted electron beam evaporation of a titanium source, and the growth temperature was varied from 300 to 600 °C. At an optimal temperature of 500 °C, X-ray diffraction measurements show that rutile phase TiO 2 films are produced. Pole figure analysis indicates that the TiO 2 layer follows the symmetry of the BaF 2 surface mesh, and consists of six (1 0 0)-oriented domains separated by 30° in-plane rotations about the TiO 2 [1 0 0] axis. The in-plane alignment between the TiO 2 and BaF 2 films is oriented as [0 0 1] TiO 2 || BaF 2 or [0 0 1] TiO 2 || BaF 2 . Rocking curve and STM analyses suggest that the TiO 2 films are more finely grained than the BaF 2 film. STM imaging also reveals that the TiO 2 surface has morphological features consistent with the BaF 2 surface mesh symmetry. One of the optimally grown TiO 2 (1 0 0) films was used to template a CrO 2 (1 0 0) film which was grown via chemical vapor deposition. Point contact Andreev reflection measurements indicate that the CrO 2 film was approximately 70% spin polarized. 相似文献
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