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1.
Munetoshi Seki Masateru Mikami Fujiyuki Iwamoto Yosuke Ono Takamasa Osone Hitoshi Tabata 《Journal of Crystal Growth》2010,312(15):2273-2278
Epitaxial thin films of TmFeCuO4 with a two-dimensional triangular lattice structure were successfully grown on yttria-stabilized-zirconia substrates by pulsed laser deposition and ex situ annealing in air. The films as-deposited below 500 °C showed no TmFeCuO4 phase and the subsequent annealing resulted in the decomposition of film components. On the other hand, as-grown films deposited at 800 °C showed an amorphous nature. Thermal annealing converted the amorphous films into highly (0 0 1)-oriented epitaxial films. The results of scanning electron microscopic analysis suggest that the crystal growth process during thermal annealing is dominated by the regrowth of non-uniformly shaped islands to the distinct uniform islands of hexagonal base. 相似文献
2.
The growth and characterization of zirconium oxide (ZrO2) thin films prepared by thermal oxidation of a deposited Zr metal layer on SiO2/Si were investigated. Uniform ZrO2 thin film with smooth surface morphology was obtained. The thermal ZrO2 films showed a polycrystalline structure. The dielectric constant of the ZrO2 film has been shown to be 23, and the equivalent oxide thickness (EOT) of the ZrO2 stacked oxide is in the range of 3.38–5.43 nm. MOS capacitors with ZrO2 dielectric stack show extremely low leakage current density, less than 10?6 A/cm2 at ?4 V. Consequently, using this method, high-quality ZrO2 films could be fabricated at oxidation temperature as low as 600 °C. 相似文献
3.
Seok-Woo Nam Jung-Ho YooSuheun Nam Hyo-Jick ChoiDongwon Lee Dae-Hong Ko Joo Ho MoonJa-Hum Ku Siyoung Choi 《Journal of Non》2002,303(1):139-143
Hafnium oxide thin films were deposited on p-type (1 0 0) silicon wafers by reactive dc magnetron sputtering. Prior to the deposition of HfO2 films, a thin Hf film was deposited. Sputtered HfO2 thin films deposited at room temperature remain amorphous at T<650°C and orthorhombic phases were observed above 650 °C. The monoclinic phase which is a stable HfO2 polymorphic form appeared after annealing above 800 °C. Capacitance equivalent thickness values decreased and leakage characteristics are improved by the Hf interlayer and O2 settlement process. The decrease of accumulation capacitance values upon annealing is due to the growth of an interfacial layer upon post-annealing. The flat band voltage (VFB) shifts negatively due to positive charge generated during post-annealing. 相似文献
4.
Tin oxide (SnO2) thin films were deposited on UV fused silica (UVFS) substrates using filtered vacuum arc deposition (FVAD). During deposition, the substrates were at room temperature (RT). As-deposited films were annealed at 400 and 600 °C in Ar for 30 min. The film structure, composition, and surface morphology were determined as function of the annealing temperature using X-ray diffraction (XRD), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). The XRD patterns of the SnO2 thin films deposited on substrates at RT indicated that the films were amorphous, however, after the annealing the film structure became polycrystalline. The grain size of the annealed films, obtained from the XRD analysis, increased with the annealing temperature, and it was in the range 8-34 nm. The AFM analysis of the surface revealed an increase in the film surface average grain size from 15 nm to 46 nm, and the surface roughness from 0.2 to 1.8 nm, as function of the annealing temperature. The average optical transmission of the films in the visible spectrum was >80%, and increased by the annealing ∼10%. The films’ optical constants in the 250-989 nm wavelength range were determined by variable angle spectroscopic ellipsometry (VASE). The refractive indexes of as-deposited and annealed films were in the range 1.83-2.23 and 1.85-2.3, respectively. The extinction coefficients, k(λ), of as-deposited and annealed films were in the range same range ∼0-0.5. The optical energy band gap (Eg), as determined by the dependence of the absorption coefficient on the photon energy at short wavelengths, increased with the annealing temperature from 3.90 to 4.35 eV. The lowest electrical resistivity of the as-deposited tin oxide films was 7.8 × 10−3 Ω cm, however, film annealing resulted in highly resistive films. 相似文献
5.
Li Wang 《Journal of Non》2011,357(3):1063-1069
Amorphous SiC has superior mechanical, chemical, electrical, and optical properties which are process dependent. In this study, the impact of deposition temperature and substrate choice on the chemical composition and bonding of deposited amorphous SiC is investigated, both 6 in. single-crystalline Si and oxide covered Si wafers were used as substrates. The deposition was performed in a standard low-pressure chemical vapour deposition reactor, methylsilane was used as the single precursor, and deposition temperature was set at 600 and 650 °C. XPS analyses were employed to investigate the chemical composition, Si/C ratio, and chemical bonding of deposited amorphous SiC. The results demonstrate that these properties varied with deposition temperature, and the impact of substrate on them became minor when deposition temperature was raised up from 600 °C to 650 °C. Nearly stoichiometric amorphous SiC with higher impurity concentration was deposited on crystalline Si substrate at 600 °C. Slightly carbon rich amorphous SiC films with much lower impurity concentration were prepared at 650 °C on both kinds of substrates. Tetrahedral Si-C bonds were found to be the dominant bonds in all deposited amorphous SiC. No contribution from Si-H/Si-Si but from sp2 and sp3 C-C/C-H bonds was identified. 相似文献
6.
Dan Seguin Madhana Sunder Lakshmi Krishna Alexander Tatarenko P.D. Moran 《Journal of Crystal Growth》2009,311(12):3235-3238
Fe0.8Ga0.2 films were deposited on bulk single-crystal (0 0 1) 0.69PMN-0.31PT substrates by DC magnetron sputtering to make magnetoelectric bilayer composites. Films deposited at temperatures below 600 °C were X-ray amorphous. Films deposited at temperatures of 600 °C and higher exhibited a single-crystal (0 0 1) disordered BCC structure. The crystalline FeGa films demonstrate a 45° twisted cube-on-cube epitaxial relationship with the PMN–PT substrates. Heterostructures with an X-ray amorphous FeGa film exhibited zero magnetoelectric response. Heterostructures with a 990 nm epitaxial FeGa film exhibited a large inverse magnetoelectric voltage coefficient of 13.4 (G cm)/V. 相似文献
7.
Fluorinated nanoporous silica (denoted as SiO2:F) thin films with low dielectric constant were prepared by a sol-gel method and spin coating technique. The leakage current densities of the SiO2:F thin films were 10−8 and 3 × 10−6 A/cm2 respectively for the as-deposited films and for those subjected to annealing at a temperature of 450 °C. These currents are more than one order of magnitude lower than those of the common SiO2 films. Photoluminescent results showed strong blue-light emission and a small blue shift in the SiO2:F films that were related to the increment of the porosity. The dielectric properties were also characterized and the k value of the annealed SiO2:F film was found to be about 1.67. The hole size in the films is small and the size distribution is uniform for the annealed SiO2:F samples due to the effects of fluorination. The underlying mechanism for fluorination is discussed in this paper. 相似文献
8.
9.
This study investigated the effect of the substrate temperature on the structural, optical, morphological, and electrical properties of undoped SnO2 films prepared by a spray deposition method. The films were deposited at various substrate temperatures ranging from 300-500 °C in steps of 50 °C and characterized by different optical and structural techniques. X-ray diffraction studies showed that the crystallite size and preferential growth directions of the films were dependent on the substrate temperature. These studies also indicated that the films were amorphous at 300 °C and polycrystalline at the other substrate temperatures used. Infrared and visible spectroscopic studies revealed that a strong vibration band, characteristic of the SnO2 stretching mode, was present around 630 cm−1 and that the optical transmittance in the visible region varied over the range 75-95% with substrate temperature, respectively. The films deposited at 400 °C exhibited the highest electrical conductivity property. 相似文献
10.
A. A. Dakhel 《Crystal Research and Technology》2003,38(11):968-973
Thin Eu2O3 films were prepared on Si (P) substrates to form MOS devices. The oxide crystal structure was determined by X‐ray diffraction (XRD). The electrical transport properties of the devices with amorphous and crystalline Eu oxide were investigated. The current‐voltage and current‐temperature characteristics suggest a Poole‐Frenkel (PF) type mechanism of carrier transport through the device when the applied field is more than 105 V/cm. A deviation from PF leakage current course was found and attributed to the current carrier trapping. We have also observed that, the dielectric spectra of MOS structure are different when the insulator is an amorphous or crystalline thin film. From which we calculate the relaxation time (τ) of the interface (insulator/semiconductor) dipoles. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
11.
T. Leistner K. LehmbacherP. Härter C. SchmidtA.J. Bauer L. Frey H. Ryssel 《Journal of Non》2002,303(1):64-68
Thin films with a considerably higher dielectric constant than silicon dioxide, for example titanium dioxide or titanium containing barium strontium titanate, can be used for dielectrics in ultralarge scale integration devices. TiO2 shows, besides its high dielectric constant, a sufficiently low leakage current and high breakdown field strength. MOCVD is the most promising method for depositing those dielectrics because of its obvious advantages like homogeneity of films, good step coverage and ultrathin film deposition. In this work, three new precursor chemicals have been developed and tested in a low pressure horizontal cold wall-type furnace. For the synthesis of the novel precursors, commercial titaniumisopropylate is brought to an reaction with an alcoholic compound at 150 °C and distilled under vacuum. The motivation for the development of new Ti precursors lies in an improvement of the handling and deposition characteristics as for example the hydrolytic stability. For the three precursors the deposition parameters temperature, pressure, gas flow and activation energy is presented. The electrical properties dielectric constant and leakage current were compared to commercially available titaniumisopropylate. 相似文献
12.
SnO2 films have been deposited on Y-stabilized ZrO2 (YSZ) (1 0 0) substrates at different substrate temperatures (500–800 °C) by metalorganic chemical vapor deposition (MOCVD). Structural, electrical and optical properties of the films have been investigated. The films deposited at 500 and 600 °C are epitaxial SnO2 films with orthorhombic columbite structure, and the HRTEM analysis shows a clear epitaxial relationship of columbite SnO2(1 0 0)||YSZ(1 0 0). The films deposited at 700 and 800 °C have mixed-phase structures of rutile and columbite SnO2. The carrier concentration of the films is in the range from 1.15×1019 to 2.68×1019 cm−3, and the resistivity is from 2.48×10−2 to 1.16×10−2 Ω cm. The absolute average transmittance of the films in the visible range exceeds 90%. The band gap of the obtained SnO2 films is about 3.75–3.87 eV. 相似文献
13.
Nitrogen-rich GaAsN thin films have been deposited at 500 °C by reactive rf sputtering of GaAs target in argon-nitrogen atmosphere. The arsenic content of the films was varied by changing the nitrogen percentage in the sputtering atmosphere and the As/Ga ratio in the films was estimated by X-ray fluorescence measurements. Spectroscopic ellipsometry measurements have been carried out on these films and the measured ellispometric spectra were fitted with theoretical spectra generated by using suitable model sample structures. From the best fit parameters of the dispersion model, band-gap values and variation of refractive index and extinction coefficient as a function of wavelength have been obtained for films deposited with different percentages of nitrogen in the sputtering atmosphere. The films deposited with 12% to 100% nitrogen in the sputtering atmosphere, which are of hexagonal GaN, exhibit GaN-like optical properties, though effects due to excess arsenic in amorphous phase are seen in the films deposited with less than 40% nitrogen. The films deposited with 5% to 12% nitrogen in sputtering atmosphere are dominantly polycrystalline GaAsxN1−x (x ≈ 0.01 to 0.08) and exhibit variations in optical parameters, which are consistent with their structure and composition. The films deposited with less than 5% nitrogen in sputtering atmosphere are arsenic-rich and amorphous. 相似文献
14.
X. H. Xu M. Wang Y. Hou S.R. Zhao H. Wang D. Wang S.X. Shang 《Crystal Research and Technology》2002,37(5):431-439
TiO2 thin films, were deposited on Si(100) and Si(111) substrates by metalorganic chemical vapor deposition at 500 °C, and have been annealed for 2 min, 30 min and 10 hours at the temperature from 600 °C to 900 °C, in oxygen and air flow, respectively. XRD and atomic force microscopy characterized the structural properties and surface morphologies of the films. As‐deposited films show anatase polycrystalline structure with a surface morphology of regular rectangled grains with distinct boundaries. Rutile phase formed for films annealed above 600 °C, and pure rutile polycrystalline films with (110) orientation can be obtained after annealing under adequate conditions. Rutile annealed films exhibit a surface morphology of equiaxed grains without distinct boundaries. The effects of substrate orientation, annealing time and atmosphere on the structure and surface morphology of films have also been studied. Capacitance‐Voltage measurements have been performed for films deposited on Si(100) before and after annealing. The dielectric properties of TiO2 films were greatly improved by thermal annealing above 600 °C in oxygen. 相似文献
15.
The crystallization dynamic of amorphous GeTe 50 nm thick films deposited on a SiO2/Si substrate by RF magnetron sputtering, either ion implanted by Ge+ ions or not, has been analyzed in situ by optical microscopy during annealing in the 143-155 °C temperature range. Raman spectroscopy has been also performed in as deposited, ion implanted (i.i.) and melt quenched (m.q.) amorphous samples to compare the local order among the different amorphous structure. Nucleation and growth rates, for i.i. and as deposited samples, have been observed and directly compared by optical microscopy in a region of about 5 × 104 μm2. From these data, the activation energy and pre-exponential terms of each process have been calculated. The nucleation rate and growth velocity of the i.i. films increased by a factor thirteen and a factor three with respect to the as deposited samples. This evidence, in agreement with Raman spectroscopy data, suggests that implantation, providing kinetic energy by collision cascade, induces a local atomic rearrangement towards more relaxed amorphous states. As a result the crystallization kinetic is enhanced by the reduction of wrong bonds formed during sputter deposition, a process which occurs far from equilibrium conditions. 相似文献
16.
C. Zhao O. RichardE. Young H. BenderG. Roebben S. HaukkaS. De Gendt M. HoussaR. Carter W. TsaiO. Van Der Biest M. Heyns 《Journal of Non》2002,303(1):144-149
One challenge in the development of high-k dielectric films is to preserve their amorphous nature during the processing of CMOS. In this work, the feasibility of using ZrO2-Al2O3 binary alloys to obtain a stable homogeneous amorphous structure in a high-k layer is investigated. In situ high temperature X-ray diffraction tests show that the onset crystallisation temperature of the binary alloy with 42 and 61 mol% Al2O3 is 900, 400 °C higher than that of the pure ZrO2. After rapid thermal process anneals up to 900 °C, the ZrAlxOy film remains amorphous. At 1000 °C, tetragonal ZrO2 forms in the ZrAlxOy film. In addition, it is demonstrated that there is no undesirable amorphous phase separation during annealing at temperatures below and equal to 900 °C in the ZrO2-Al2O3 system. 相似文献
17.
The sol-gel route has been applied to obtain ZnO-TiO2 thin films. For comparison, pure TiO2 and ZnO films are also prepared from the corresponding solutions. The films are deposited by a spin-coated method on silicon and glass substrates. Their structural and vibrational properties have been studied as a function of the annealing temperatures (400-750 °C). Pure ZnO films crystallize in a wurtzite modification at a relatively low temperature of 400 °C, whereas the mixed oxide films show predominantly amorphous structure at this temperature. XRD analysis shows that by increasing the annealing temperatures, the sol-gel Zn/Ti oxide films reveal a certain degree of crystallization and their structures are found to be mixtures of wurtzite ZnO, Zn2TiO4, anatase TiO2 and amorphous fraction. The XRD analysis presumes that Zn2TiO4 becomes a favored phase at the highest annealing temperature of 750 °C. The obtained thin films are uniform with no visual defects. The optical properties of ZnO-TiO2 films have been compared with those of single component films (ZnO and TiO2). The mixed oxide films present a high transparency with a slight decrease by increasing the annealing temperature. 相似文献
18.
Chao-Yang Tsao Patrick Campbell Dengyuan Song Martin A. Green 《Journal of Crystal Growth》2010,312(19):2647-2655
To improve the properties of polycrystalline Ge thin films, which are a candidate material for the bottom cells of low cost monolithic tandem solar cells, ∼300 nm in situ hydrogenated Ge (Ge:H) thin films were deposited on silicon nitride coated glass by radio-frequency magnetron sputtering. The films were sputtered in a mixture of 15 sccm argon and 10 sccm hydrogen at a variety of low substrate temperatures (Ts)≤450 °C. Structural and optical properties of the Ge:H thin films were measured and compared to those of non-hydrogenated Ge thin films deduced in our previous work. Raman and X-ray diffraction spectra revealed a structural evolution from amorphous to crystalline phase with increase in Ts. It is found that the introduction of hydrogen gas benefits the structural properties of the polycrystalline Ge film, sputtered at 450 °C, although the onset crystallization temperature is ∼90 °C higher than in those sputtered without hydrogen. Compared with non-hydrogenated Ge thin films, hydrogen incorporated in the films leads to broadened band gaps of the films sputtered at different Ts. 相似文献
19.
Zengfeng Di Miao Zhang Weili Liu Suhua Luo Zhenghua An Zhengxuan Zhang Chenglu Lin 《Journal of Non》2005,351(1):93-96
Zr0.6Al0.4O1.8 dielectric films were deposited directly on strained SiGe substrates at room temperature by ultra-high vacuum electron-beam evaporation (UHV-EBE) and then annealed in N2 under various temperatures. X-ray diffraction (XRD) reveals that the onset crystallization temperature of the Zr0.6Al0.4O1.8 film is about 900 °C, 400 °C higher than that of pure ZrO2. The amorphous Zr0.6Al0.4O1.8 film with a physical thickness of ∼12 nm and an amorphous interfacial layer (IL) with a physical thickness of ∼3 nm have been observed by high-resolution transmission electron microscopy (HRTEM). In addition, it is demonstrated there is no undesirable amorphous phase separation during annealing at temperatures below and equal to 800 °C in the Zr0.6Al0.4O1.8 film. The chemical composition of the Zr0.6Al0.4O1.8 film has been studied using secondary ion mass spectroscopy (SIMS). 相似文献
20.
R. Matero M. RitalaM. Leskelä A.C. Jones P.A. WilliamsJ.F. Bickley A. SteinerT.J. Leedham H.O. Davies 《Journal of Non》2002,303(1):24-28
Zirconium oxide thin films were grown by atomic layer deposition using a new type of Zr alkoxide: [Zr(OtBu)2(dmae)2]2 (dmae is dimethylaminoethoxide). Water was used as the oxygen source. The films grown at 190-240 °C were amorphous, and the films grown at 290-340 °C were nanocrystalline. The highest refractive index of the films was 2.08 at a wavelength of 580 nm. The permittivity of a film grown at 240 °C was 25. 相似文献