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81.
Near-eutectic Cr–Cr3Si alloys were directionally solidified in a high-temperature optical floating zone furnace. At the eutectic composition, uniform and well-aligned lamellar structures were obtained over a fairly wide range of solidification conditions, but not at very low or very high growth rates where degenerate and cellular structures, respectively, were obtained. The lamellar spacing was found to increase with decreasing solidification rate, in agreement with the Jackson–Hunt theory. In addition, for a fixed growth rate, the lamellar spacing was found to increase with increasing rotation rate. The growth directions in the lamellar eutectic are found to be 1 0 0 for the Cr3Si phase and 1 1 1 for the Cr solid-solution phase. Eutectic microstructures (rod or lamellar) could also be produced at off-eutectic compositions, but only for a limited range of growth conditions. 相似文献
82.
The formation of self-aligned Ti(Si(1−x)Ge(x))2 on submicron lines is described. The silicide/germanide is formed by reacting sputtered Ti with epitaxially grown Si(1−x)Ge(x) of composition and thickness relevant to high mobility Si(1−x)Ge(x) channel field effect transistors. Ti(Si(1−x)Ge(x))2 formation on narrow lines was carried out on phosphorous doped material, because of the well known difficulties of forming
silicide on heavily n-doped silicon. A companion set of boron doped blanket films was also processed. The results show that
the process temperature required for the minimization of silicide/germanide sheet resistance is reduced as compared to silicide
formation on Si alone. However, the silicide/germanide films agglomerate with increased high temperature processing more easily
than pure silicide. The thermal stability is degraded more for films with higher Ge content and is a strong function of dopant
type. Silicide/germanide formation on phosphorous doped Si(1−x)Ge(x) layers with x = 10% have a line width dependence similar to silicide formation. Formation on phosphorous doped Si(1−x)Ge(x) layers with x = 27% display an inverse line width dependence, with higher overall sheet resistance. Formation of silicide/germanide
on blanket films of boron doped Si(1−x)Ge(x) with x = 27% behaved similar to the formation of silicide on silicon. 相似文献
83.
Cobalt disilicide is grown epitaxially on (100) Si from a 15 nm Co/2 nm Ti bilayer by rapid thermal annealing (RTA) at 900°C.
Polycrystalline CoSi2 is grown on (100) Si using a 15 nm Co layer and the same annealing condition. Silicide/p+-Si/n-Si diodes are made using the silicide as dopant source:11B+ ions are implanted at 3.5–7.5 kV and activated by RTA at 600–900°C. Shallow junctions with total junction depth (silicide
plus p+ region) measured by high-resolution secondaryion mass spectroscopy of 100 nm are fabricated. Areal leakage current densities
of 13 nA/cm2 and 2 nA/cm2 at a reverse bias of -5V are obtained for the epitaxial silicide and polycrystalline silicide junctions, respectively, after
700°C post-implant annealing. 相似文献
84.
The thermal stability of Ti/Pt/Au Schottky contacts on n-GaAs with Ti films 0–60 nm is investigated. The contacts with Ti films as small as 10 nm remain thermally stable with annealing up to 400°C. The changes induced by thermal treatment in the electrical characteristics of the contacts are correlated with the Rutherford backscattering and microscopic analysis of the annealed samples. It shows profuse interdiffusion and interfacial reaction with 300°C anneal for the GaAs/Pt/Au system. It has been found that introducing the Ti film between GaAs and Pt/Au, the interdiffusion of Pt and Au is also prevented. These results are useful for reducing the gate metallisation resistance of metal semiconductor field effect transistors. 相似文献
85.
The formation of CoSi2 on strained epitaxial Si0.8Ge0.2/Si(100) films has been studied as a function of the deposition method and annealing temperature. Two types of deposition processes were used: a direct method, where 5 nm of pure Co metal were deposited at room temperature onto a strained 80 nm thick Si0.8Ge0.2 layer; and a co-deposition method, where 5 nm Co and 18.2 nm Si were simultaneously deposited in a 1:2 ratio onto a strained Si0.8Ge0.2 layer at 450°C. Samples were then annealed at temperatures ranging from 500 to 800°C. Extended X-ray absorbance fine structure spectroscopy (EXAFS) and X-ray diffraction (XRD) were used to characterize the structure of the resulting films. It was found that the samples prepared via the direct deposition method did not convert to CoSi2 at any annealing temperature up to 800°C, while the co-deposited samples formed epitaxial CoSi2 at even the lowest annealing temperature of 500°C. These results are discussed in terms of proposed reaction mechanisms of the different deposition methods, based on consideration of the Co–Si–Ge ternary phase diagram. 相似文献
86.
本文以四氯化钛(TiCl4)和硅烷(SiH4)为源物质,采用等离子增强化学气相淀积(PECVD)工艺结合常规热退火制备了优良的TiSi2薄膜。研究了淀积和退火条件对薄膜性质的影响。用四探针检测了退火前后薄膜的薄层电阻,用俄歇电子能谱(AES)和X射线衍射分析了薄膜的化学组成和晶体结构。 相似文献
87.
K. Mars H. Ihou-Mouko G. Pont J. Tobola H. Scherrer 《Journal of Electronic Materials》2009,38(7):1360-1364
Mg2Si1−x
Ge
x
compounds were prepared from pure elements by melting in tantalum crucibles. The reaction was conducted under an inert gas
in a special laboratory setup. Samples for thermoelectric measurements were formed by hot pressing. Structure and phase composition
of the obtained materials were investigated by x-ray diffraction (XRD). Morphology and chemical composition were examined
by scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDS), respectively. Thermoelectric properties,
i.e., the Seebeck coefficient, the electrical conductivity, and the thermal conductivity, were measured in the temperature
range of 500 K to 900 K. The effect of Bi and Ag doping on the thermoelectric performance of Mg-Si-Ge ternary compounds was
investigated. The electronic structures of binary compounds were calculated using the Korringa–Kohn–Rostoker (KKR) method.
The effects of disorder, including Ge substitution and Bi or Ag doping, were accounted for in the KKR method with coherent
potential approximation calculations. The thermoelectric properties of doped Mg2Si1−x
Ge
x
are discussed with reference to computed density of states as well as the complex energy band structure. 相似文献
88.
The concept of using an ambipolar bilayer semiconducting heterostructure in organic light-emitting transistors (OLETs) is introduced to provide a new approach to achieve surface emission. The properties of top-gate-type bilayer OLETs with ambipolar materials based on two types of fluorene-type polymers used as an emissive layer and an electron blocking layer are investigated. Line-shaped yellow–green emission occurs near a hole-injection electrode. When hole transport is dominant in the upper layer which acts as an electron blocking layer, and electrons are injected into the lower layer, an in-plane light-emitting pattern is observed. The measured in-plane emission zone confirms that both hole and electron transport are determined to occur mainly along the different organic layers between the source and drain electrodes, and an in-plane recombination zone of electrons and holes exists near the bilayer organic interface. This work is anticipated to be useful for the development of in-plane light-emitting transistors. 相似文献
89.
Bin Du Chao He Junjie Qian Ping Hu Xuan Wang Mei Cai Anze Shui 《International Journal of Applied Ceramic Technology》2020,17(4):1785-1789
In this work, high-purity HfSi2 powders were successfully fabricated via a molten salt-assisted magnesium thermal reduction method using HfO2 and Si as raw materials. The effects of reaction temperature and time on the formation of HfSi2 were systemically investigated. The morphological and phase composition of as-prepared HfSi2 powders were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and nitrogen/oxygen determinator. The results indicated that as-obtained HfSi2 powders possess the orthorhombic structure with approximately 6.4 μm in size and the oxygen content as low as 0.20%. This work can provide a novel route to fabricate the high-purity transition metal silicides powders. 相似文献
90.
采用极化曲线,塔菲尔图(Tafel Plot),交流阻抗(EIS)及浸泡腐蚀技术,研究了激光熔化沉积γ/Mo2Ni3Si合金在不同酸,碱,盐介质中的腐蚀行为。结果表明,该合金在1mol/L NaOH溶液中,由于形成了稳定的钝化膜,耐蚀性优异;在1mol/LH2SO4溶液中,合金只能形成不稳定的钝化膜;而在含Cl^-的中性或酸性介质中,合金没有钝化趋势,且由浸泡腐蚀试验表明,在1mol/LHCl溶液中,由于Cl^-导致相界腐蚀,合金耐蚀性较差。 相似文献