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1.
Single phase TiN and AlN films were prepared on a Si wafer from titanium tetra-etoxide and aluminum tri-butoxide solutions dissolved in ethanol and toluene, respectively, using an Ar/N 2/H 2 radio-frequency (r.f.) inductive thermal plasma chemical vapor deposition (CVD) method. The films were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, measurement of electrical resistivity and Vickers microhardness. Factors affecting the formation of the films (lattice parameter, chemical composition, oxygen/carbon content, and deposition rate of the films) were examined in terms of the N 2 flow rate (2.5–4.5 slm), substrate temperature (300–700°C), feed rate of the solution (0.025–0.3 ml/min), and the mole ratio of the alkoxide solution (1:1–1:3). The optimum conditions for preparation of TiN films produced a film 0.2–3 μm thick with an oxygen content of 8 at.% and a free carbon content of 4 at.%, showing an electrical resistivity of 370 μΩ cm. The optimum conditions for AlN films produced a film 0.3 μm thick containing 14 at.% oxygen and 8 wt.% carbon. The deposition rate of the TiN film was determined to be 30–35 nm/min. The Vickers microhardness of the TiN and AlN films was found to be 10±1 and 13±3 GPa, respectively. 相似文献
2.
A series of 0.2–0.6 μm thick SnO x films were deposited onto borosilicate and sodalime silica glass substrates by atmospheric plasma discharge chemical vapor deposition at 80 °C. SnO x films deposited from monobutyltin trichloride contained a large percentage of SnCl 2:2H 2O, and therefore were partially soluble in water. SnO x coatings deposited from tetrabutyltin were not soluble in water or organic solvents, had good adhesion even at growth rates as high as 2.3 nm/s, had high transparency of 90% and electrical resistivity of 10 7 Ω cm. As-grown tin oxide coatings were amorphous with a small concentration of SnO 2, SnO and Sn crystalline phases as determined by grazing angle X-ray diffraction and X-ray photoelectron spectroscopy measurements. Upon annealing in air at 600 °C the resistivity of SnO x films decreased to 5–7 Ω cm. Furthermore, optical and X-ray measurements indicated that SnO x was converted into SnO 2 (cassiterite) with a direct band gap of 3.66 eV. Annealing of as-grown SnO x films in vacuum at 340 °C led to formation of the p-type conductor SnO/SnO x. The indirect band gap of SnO was calculated from the optical spectra to be 0.3 eV. 相似文献
3.
Doping and electrical characteristics of in-situ heavily B-doped Si 1−x−yGe xC y (0.22< x<0.6, 0< y<0.02) films epitaxially grown on Si(100) were investigated. The epitaxial growth was carried out at 550°C in a SiH 4–GeH 4–CH 3SiH 3–B 2H 6–H 2 gas mixture using an ultraclean hot-wall low-pressure chemical vapor deposition (LPCVD) system. It was found that the deposition rate increased with increasing GeH 4 partial pressure, and only at high GeH 4 partial pressure did it decrease with increasing B 2H 6 as well as CH 3SiH 3 partial pressures. With the B 2H 6 addition, the Ge and C fractions scarcely changed and the B concentration ( CB) increased proportionally. The C fraction increased proportionally with increasing CH 3SiH 3 partial pressures. These results can be explained by the modified Langmuir-type adsorption and reaction scheme. In B-doped Si 1−x−yGe xC y with y=0.0054 or below, the carrier concentration was nearly equal to CB up to approximately 2×10 20 cm −3 and was saturated at approximately 5×10 20 cm −3, regardless of the Ge fraction. The B-doped Si 1−x−yGe xC y with high Ge and C fractions contained some electrically inactive B even at the lower CB region. Resistivity measurements show that the existence of C in the film enhances alloy scattering. The discrepancy between the observed lattice constant and the calculated value at the higher Ge and C fraction suggests that the B and C atoms exist at the interstitial site more preferentially. 相似文献
4.
In this paper, bulk-Si metal–oxide–semiconductor field effect transistors (MOSFETs) are fabricated using the catalytic chemical vapor deposition (Cat-CVD) method as an alternative technology to the conventional high-temperature thermal chemical vapor deposition. Particularly, formation of low-resistivity phosphorus (P)-doped poly-Si films is attempted by using Cat-CVD-deposited amorphous silicon (a-Si) films and successive rapid thermal annealing (RTA) of them. Even after RTA processes, neither peeling nor bubbling are observed, since hydrogen contents in Cat-CVD a-Si films can be as low as 1.1%. Both the crystallization and low resistivity of 0.004 Ω·cm are realized by RTA at 1000 °C for only 5 s. It is also revealed that Cat-CVD SiN x films prepared at 250 °C show excellent oxidation resistance, when the thickness of films is larger than approximately 10 nm for wet O 2 oxidation at 1100 °C. It is found that the thickness required to stop oxygen penetration is equivalent to that for thermal CVD SiN x prepared at 750 °C. Finally, complementary MOSFETs (CMOSs) of single-crystalline Si were fabricated by using Cat-CVD poly-Si for gate electrodes and SiN x films for masks of local oxidation of silicon (LOCOS). At 3.3 V operation, less than 1.0 pA μm −1 of OFF leakage current and ON/OFF ratio of 10 7–10 8 are realized, i.e. the devices can operate similarly to conventional thermal CVD process. 相似文献
5.
B-doped a-Si 1−xC x:H films for a window layer of Si thin film solar cells have been prepared by the Cat-CVD method. It is found that C is effectively incorporated into the films by using C 2H 2 as a C source gas, where an only little C incorporation is observed from CH 4 and C 2H 6 under similar deposition conditions. Using a-Si 1−xC x:H films grown from C 2H 2, heterojunction p–i–n solar cells have been prepared by the Cat-CVD method. The cell structure is (SnO 2 Asahi-U)/ZnO/a-Si 1−xC x:H(p)/a-Si:H(i)/μc-Si:H(n)/Al. The obtained conversion efficiency was 5.4%. 相似文献
6.
We have investigated the stress behaviors and a mechanism of void formation in TiSi x films during annealing. TiSi x thin films were prepared by DC magnetron sputtering using a TiSi 2.1 target in the substrate temperature range of 200–500 °C. The as-deposited TiSi x films at low substrate temperature (<300 °C) have an amorphous structure with low stress of 1×10 8 dynes/cm 2. When the substrate temperature increases to 500 °C, the as-deposited TiSi x film has a mixture of C49 and C54 TiSi 2 phase with stress of 8×10 9 dynes/cm 2. No void was observed in the as-deposited TiSi x film. Amorphous TiSi x film transforms to C54 TiSi 2 phase with a random orientation of (311) and (040) after annealing at 750 °C. The C49 and C54 TiSi 2 mixture phase transforms to (040) preferred C54 TiSi 2 phase after annealing over 650 °C. By increasing substrate temperature, the transformation temperature for C54 TiSi 2 can be reduced, resulting in relieved stress of TiSi 2 film. The easy nucleation of the C54 phase was attributed to an avoidance of amorphous TiSi x phase. We found that amorphous TiSi x→C54 TiSi 2 transformation caused higher tensile stress of 2×10 10 dynes/cm 2, resulting in more voids in the films, than C49→C54 transformation. It was observed that void formation was increased with thermal treatment. The high tensile stress caused by volume decreases in the silicide must be relieved to retard voids and cracks during C54 TiSi 2 formation. 相似文献
7.
a-C:H and a-C:H/SiO x nanocomposite thin films were deposited on silicon, aluminum and polyimide substrates at 25 °C in an asymmetric 13.56 MHz r.f.-driven plasma reactor under heavy ion bombardment. Fourier transform infrared spectra of the films indicate that the nanocomposite filmsappears to consist of an atomic scale random network of a-C:H and SiO x. Raman spectroscopy revealed that the sp 2 carbon fraction in the nanocomposite film was reduced compared with the a-C:H film. The intrinsic stress of both films increased with increasing negative bias voltage (− Vdc) at the substrate. However, the nanocomposite films exhibited lower intrinsic stress compared w with a-C:H-only films. Especially, a thin SiO x-rich interlayer was very effective in reducing the film stress and enhancing the bonding strength at the interface. The interlayer allowed deposition of thick films of up to 5 μm. Also, the nanocomposite films were stable in 0.1 M NaOH solution and showed good microhardness. 相似文献
8.
Y xGd 1−xVO 4:Tm 3+ (5 mol%) phosphors were prepared by in situ co-precipitation technology with the different content ratio of Y/Gd ( x = 0.2, 0.3, 0.4, 0.5, 0.6, 0.8, respectively). During the process, rare earth coordination polymers with o-hydroxylbenzoate were used as precursors, composing with polyethylene glycol (PEG) as dispersing media. After heat-treatment of the resulting multicomponent hybrid precursors at 900 °C, the samples were obtained. SEM indicated the particles present good crystalline state, whose crystalline grain sizes were about 0.2–2 μm. Under the excitation of 257 nm, all the materials show the characteristic emission of Tm 3+ which is the strong blue emission centered at 475 nm originating from 1G 4 → 3H 6 of Tm 3+. Besides this, concentration quenching appears in the system of YVO 4:Tm 3+ and GdVO 4:Tm 3+. And when x reaches 0.5, the system of Y xGd 1−xVO 4:Tm 3+ shows the strongest blue emission. 相似文献
9.
The changes of the crystallinity of μc-Si phase are studied in samples deposited with hydrogen dilution ratio, H 2/SiH 4, from 9.0 to 19.0 by hot-wire CVD (Cat-CVD). In the samples deposited at filament temperature, Tf, of 1850 °C, the crystalline fraction and the crystallite size of μc-Si phase increased with increasing the H 2/SiH 4. The carbon content, C/(Si+C), was almost constant. In the XRD patterns, the intensity of Si(1 1 1) peak decreased and that of Si(2 2 0) peak increased with increasing the H 2/SiH 4. In the samples deposited at Tf of 2100 °C with H 2/SiH 4 over 11.4, the μc-Si phase was not formed and the C/(Si+C) increased. The growth mechanism of μc-Si in hetero-structured SiC x alloy films is discussed. 相似文献
10.
Nanocrystalline Ba 1−xSr xTiO 3 ( x=0, 0.2, 0.4, 0.6, 0.8 and 1.0) precursors were synthesized using the stearic acid gel method. After the precursors had been calcined at 600–950°C for 0.5–1 h, nanocrystalline powders with the cubic perovskite structure were obtained and these were made into thick films. The powder samples were characterized by differential thermal analysis, X-ray diffraction and transmission electron microscopy, and the thick film samples were characterized by scanning electron microscopy and X-ray diffraction. The humidity-sensitive properties of the nanocrystalline Ba 1−xSr xTiO 3 thick films were investigated. The results show that these nanocrystalline thick films possess higher humidity sensitivity and lower resistance than those of conventional materials. 相似文献
11.
(Ti, Al)N films have drawn much attention as alternatives for TiN coatings, which are oxidized easily in air above 500 °C. We have investigated the effect of Al content on the oxidation resistance of (Ti 1 − xAl x)N films prepared by r.f. reactive sputtering. (Ti1 − xAlxN films (O ≤ x ≤ 0.55) were deposited onto fused quartz substrates by r.f. reactive sputtering. Composite targets with five kinds of Al-to-Ti area ratio were used. The sputtering gas was Ar (purity, 5 N) and N2 (5 N). The flow rate of Ar and N2 gas was kept constant at 0.8 and 1.2 sccm, respectively, resulting in a sputtering pressure of 0.4 Pa. The r.f. power was 300 W for all experiments. Substrates were not intentionally heated during deposition. The deposited films (thickness, 300 nm) were annealed in air at 600 900 °C and then subjected to X-ray diffractometer and Auger depth profiling. The as-deposited (Ti1 − xAlx)N films had the same crystal structure as TiN (NaCl type). Al atoms seemed to substitute for Ti in lattice sites. The preferential orientation of the films changed with the Al content of the film, x. Oxide layers of the films grew during annealing and became thicker as the annealing temperature increased. The thickness of the oxide layer grown on the film surface decreased with increasing Al content in the film. For high Al content films an Al-rich oxide layer was grown on the surface, which seemed to prevent further oxidation. All of the films, however, were oxidized by 900 °C annealing, even if the Al content was increased up to 0.55. 相似文献
12.
以AlN粉末为原料, 添加稀土氧化物(Sm 2O 3、Y 2O 3), 在氮气气氛下, 采用SPS烧结方法制备AlN陶瓷, 研究稀土氧化物的掺杂对AlN烧结试样相组成、微观结构和电性能的影响。实验表明: Sm 2O 3、Y 2O 3与Al 2O 3反应生成的液相稀土金属铝酸盐会提高AlN陶瓷致密度, 且在晶界处形成导电通路降低了AlN陶瓷电阻率。随着Sm 2O 3掺杂量的增加, 晶界相逐渐由Sm 4Al 2O 9过渡到SmAlO 3, 且Sm 4Al 2O 9对电阻率贡献最大。其中, 3wt% Sm 2O 3掺杂AlN陶瓷电阻率最低, 为 相似文献
13.
TiN (4.5 nm)/AlN (3, 6, 22 nm) superlattices deposited by DC magnetron sputtering on MgO(001) at a temperature of 850°C exhibit Raman signals. They indicate N and Ti vacancies (as in thick TiN) in TiN 1−x layers ( x=3±2%). x is higher for the sample with 3-nm thick AlN layers, which is ascribed to N diffusion from AlN (standing close to the TiN interfaces) to TiN. In comparison to Raman peaks of thick AlN, there are split signals of wurzite AlN phase, and a signal from another phase, which might be defective rocksalt AlN standing close to the TiN interfaces. The Raman signals clearly show interactions between AlN and TiN layers. 相似文献
14.
Gadolinium-doped, yttrium oxide thin films have been deposited on silicon (001) substrates by radio-frequency (RF) magnetron reactive sputtering that exhibit cathodoluminescence (CL) at ultraviolet frequencies. The maximum CL brightness occurred at λ314–315 nm characteristic of the 6P 3 / 2 → 8S ( λ = 314 nm) transition observed in Gd-doped, yttrium oxide powders. The radiative recombination takes place at the rare earth activator Gd 3+ site embedded in the Y 2O 3−δ host; the optical transition resides within the band gap of the Y 2O 3−δ host and the transition observed is characteristic of atomic gadolinium. A combinatorial approach to sputtering was used to deposit a film of variable composition from 1 to 23 at.% Gd in Y 2O 3−δ in order to rapidly discern the composition node of optimal CL brightness. A simulation was created for the purpose of predicting the film combinatorial composition for binary and ternary alloys prior to sputtering experiments in order to facilitate our combinatorial thin film synthesis technique. The model prediction varied from the real experimental composition profile by only 2.2 at.% Gd ± 1.6 at.% proving the predictor as a useful aide to complement combinatorial thin film experiments. A film of composition Y 1.56Gd 0.44O 3.25 (8.3 at.% Gd) yielded the maximum CL brightness. CL brightness increased continuously up to the 8.3 at.% Gd composition due to the increased number of activators present in the host. Beyond this composition the brightness drastically decreased. The oxygen composition in the combinatorial film was strongly dependent on the Gd composition; films were sub-stoichiometric δ > 0 below 6 at.% Gd and was over-stoichiometric δ < 0 beyond this composition. 相似文献
15.
Experimental data on the phase formation process of amorphous Ir xSi 1−x thin films with 0.30 ≤ x ≤ 0.41 are presented and discussed in relation to electric transport properties. The structure formation process at temperatures from 300 K up to 1223 K was investigated by means of X-ray diffraction. Distinct phases were observed in the final stage in dependence on the initial composition: Ir 3Si 4, Ir 3Si 5, and IrSi 3. An unknown metastable phase was found in films with a silicon concentration of 61 at.% to 64 at.% after annealing above the crystallization temperature T = 970 K. The crystal structure of this phase was determined by the combined use of X-ray diffraction and electron diffraction. It was found to be monoclinic, basic-face centred with lattice constants a = 1.027 nm, b = 0.796 nm, c = 0.609 nm, and γ = 113.7°. Additionally, microstructure and morphology of the films were investigated by transmission electron microscopy (TEM). The annealing process was studied by means of mechanical stress investigations as well as by electrical resistivity and thermopower measurements. Correlations between the structure, the phase formation and the electrical transport behaviour are discussed on the basis of conduction mechanism. 相似文献
16.
In the present work, the AC magnetoimpedance effect in La 0.7Ca 0.3MnO 3−δ at various temperatures are investigated. The peak of the metal–insulator transition occurs in the temperature dependence of impedance. Negative magnetoimpedance effect in the La 0.7Ca 0.3MnO 3−δ is obtained at frequencies f≤10 MHz. In the magnetoimpedance effect of manganites, the magnetic field not only decreases the permeability μt, but also reduces the resistivity ρ by aligning the local spins and varying the transfer integral tij. The AC magnetoimpedance participated by the DC colossal magnetoresistance (CMR) in manganites, should be connected with the combined effects of double exchange interaction, electron–phonon coupling and skin effect. 相似文献
17.
The crystallization behavior of a-Si 1−xC x:H/Al films after annealing has been investigated by transmission electron microscopy and Raman scattering. It is found that the crystallization process is complex and non-uniform, and that both equiaxial and branching Si grains with many twins and stacking faults arise at annealing temperatures as low as 250 °C. Both fine polycrystalline β-SiC grains and fractal-like -SiC aggregates are first observed in a few regions in a-Si 1−xC x:H/Al films annealed at 350 °C. The increase of the Al grain size can cause a decrease in the crystallization temperature and a rise in the grain growth rate of Si. At higher annealing temperatures, the reaction process SiC+Al→Al 4C 3+Si is predominant. 相似文献
18.
The Ba xSr 1−xTiO 3 (BST)/Pb 1−xLa xTiO 3 (PLT) composite thick films (20 μm) with 12 mol% amount of xPbO–(1 − x)B 2O 3 glass additives ( x = 0.2, 0.35, 0.5, 0.65 and 0.8) have been prepared by screen-printing the paste onto the alumina substrates with silver bottom electrode. X-ray diffraction (XRD), scanning electron microscope (SEM) and an impedance analyzer and an electrometer were used to analyze the phase structures, morphologies and dielectric and pyroelectric properties of the composite thick films, respectively. The wetting and infiltration of the liquid phase on the particles results in the densification of the composite thick films sintered at 750 °C. Nice porous structure formed in the composite thick films with xPbO–(1 − x)B 2O 3 glass as the PbO content ( x) is 0.5 ≥ x ≥ 0.35, while dense structure formed in these thick films as the PbO content ( x) is 0.8 ≥ x ≥ 0.65. The volatilization of the PbO in PLT and the interdiffusion between the PLT and the glass lead to the reduction of the c-axis of the PLT phase. The operating temperature range of our composite thick films is 0–200 °C. At room temperature (20 °C), the BST/PLT composite thick films with 0.35PbO–0.65B 2O 3 glass additives provided low heat capacity and good pyroelectric figure-of-merit because of their porous structure. The pyroelectric coefficient and figure-of-merit FD are 364 μC/(m 2 K) and 14.3 μPa −1/2, respectively. These good pyroelectric properties as well as being able to produce low-cost devices make this kind of thick films a promising candidate for high-performance pyroelectric applications. 相似文献
19.
Pt-PtO x thin films were prepared on Si(100) substrates at temperatures from 30 to 700°C by reactive r.f. magnetron sputtering with platinum target. Deposition atmosphere was varied with O 2/Ar flow ratio. The deposited films were characterized by X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy. Resistively of the deposited films was measured by d.c. four probe method. The films mainly consisted of amorphous PtO and Pt 3O 4 (or Pt 2O 3) below 400°C, and amorphous Pt was increased in the film as a deposition temperature increased to 600°C. When deposition temperature was thoroughly increased, (111) oriented pure Pt films were formed at 700°C. Compounds included in the films strongly depended on substrate temperature rather than O 2/Ar flow ratio. Electrical resistivity of Pt-PtO x films was measured to be from the order of 10 −1 Ω cm to 10 −5 Ω cm, which was related to the amount of Pt phase included in the deposited films. 相似文献
20.
High quality GaN epitaxial layers were obtained with Al xGa 1−xN buffer layers on 6H–SiC substrates. The low-pressure metalorganic chemical vapor deposition (LP-MOCVD) method was used. The 500 Å thick buffer layers of Al xGa 1−xN (0≤ x≤1) were deposited on SiC substrates at 1025°C. The FWHM of GaN (0004) X-ray curves are 2–3 arcmin, which vary with the Al content in Al xGa 1−xN buffer layers. An optimum Al content is found to be 0.18. The best GaN epitaxial film has the mobility and carrier concentration about 564 cm 2 V −1 s −1 and 1.6×10 17 cm −3 at 300 K. The splitting diffraction angle between GaN and Al xGa 1−xN were also analyzed from X-ray diffraction curves. 相似文献
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