共查询到20条相似文献,搜索用时 15 毫秒
1.
W. Wong-Ng Z. Yang L.P Cook J. Frank M. Loung Q. Huang 《Journal of Electronic Materials》2007,36(10):1279-1287
For applications ranging from phase equilibria to the processing of second-generation high T
c superconductor-coated-conductors, phase diagrams constructed under carbonate-free conditions are needed. Subsolidus phase
equilibria of BaO-R2O3-CuO
z
(R = Ho) have been investigated at (810°C), 21 kPa (875°C) and 0.1 MPa (850 and 930°C) by applying controlled atmosphere methods to minimize the presence of
carbonate and CO2 and H2O contamination. Under carbonate-free conditions, most of these phase diagrams are different from those reported in the literature.
In this paper, we also review and compare the phase diagrams of ten BaO-R2O3-CuO
z
systems (R = Nd, Sm, Eu, Gd, Dy, Y, Ho, Er, Tm and Yb) that were previously determined in this laboratory under Among these diagrams, a distinct trend of phase formation and tie-line relationships is observed. 相似文献
2.
C. André D. Vasilevskiy S. Turenne R. A. Masut 《Journal of Electronic Materials》2009,38(7):1061-1067
Thermoelectric (TE) generator modules for a number of waste heat recovery applications are required to operate between room
temperature and 500 K, a temperature range for which the composition of bismuth-telluride-based alloys needs to be adjusted
to optimize performance. In particular n-type alloys do not perform as well as p-type and require a more systematic study. We have produced, by mechanical alloying followed by hot extrusion, alloys, within the range with fixed carrier concentration () to optimize their TE performance in the temperature range 300 K to 420 K. The optimum composition has been identified to
be and which is very close to the composition that also maximizes the ratio of the electron mobility to the lattice component of
the thermal conductivity. The optimized alloy performance can be further increased by adjusting the carrier concentration. 相似文献
3.
S.K. Chan S.K. Lok G. Wang Y. Cai N. Wang I.K. Sou 《Journal of Electronic Materials》2008,37(9):1344-1348
Nanotrenches are induced by thermal annealing Au droplets on ZnSe surfaces. High-resolution scanning electron microscopy studies
of the nanotrench structures reveal that the preferred migration directions of the catalyst droplets are along the direction family. On a ZnSe(111)B surface, each of the trenches is along one of the six directions while on a nonvicinal ZnSe(100) surface, the trenches are along a pair of antiparallel directions. Based on the results obtained from atomic force microscopy surface profiling and electron energy-loss spectroscopy
chemical analysis techniques, a model is proposed to describe the possible formation mechanisms of the␣observed nanotrenches.
The highly parallel nanotrenches induced on the Au/ZnSe(100) structure as revealed in this study are potentially useful as
a template for in situ fabrication of ordered one-dimensional nanostructures (such as nanowires) of many materials. 相似文献
4.
Ohmic contacts to n-type 4H- and 6H-SiC without postdeposition annealing were achieved using an interlayer of epitaxial InN beneath a layer of
Ti. The InN films were grown by reactive dc magnetron sputtering at 450°C, whereas the Ti films were deposited by electron-beam
evaporation at room temperature. The InN films were characterized by x-ray diffraction (XRD), secondary electron microscopy
(SEM), cross-sectional transmission electron microscopy (TEM), and Hall-effect measurements. Both XRD and TEM observations
revealed that the Ti and InN films have epitaxial relationships with the 6H-SiC substrate as follows: (0001)[]Ti∥(0001)[]InN∥(0001)[]6H-SiC. The Ti/InN/SiC contacts displayed ohmic behavior, whereas Ti/SiC contacts (without an InN interlayer) were nonohmic. These
results suggest that InN reduces the Schottky barrier height at the SiC surface via a small conduction-band offset and support previous reports of an electron accumulation layer at the surface of InN. 相似文献
5.
6.
J.D. Benson R.N. Jacobs J.K. Markunas M. Jaime-Vasquez P.J. Smith L.A. Almeida M. Martinka M.F. Vilela U. Lee 《Journal of Electronic Materials》2008,37(9):1231-1236
X-ray diffraction full-width at half-maximum (XRD FWHM), reflection high-energy electron diffraction (RHEED), and atomic force
microscopy (AFM) indicate a mosaic structure for molecular-beam epitaxy (MBE) (211)B CdTe/Si. AFM measurements indicate long,
thin, small-angle-disoriented grains for CdTe/Si epilayers. These disoriented grains are ~1 μm in the [] direction and are ~40 nm in the [] direction. The RHEED pattern in the [] direction depicts nearly ideal single-crystal periodicity. The RHEED pattern in the [] direction is indicative of small-angle-disoriented crystalline grains. Scanning electron microscopy (SEM), AFM, and XRD
measurements all indicate an approximate factor of 10 increase in the Everson etch pit density (EPD) over standard Nomarski
microscopy Everson EPD determination. 相似文献
7.
Hisashi Masui Samantha C. Cruz Shuji Nakamura Steven P. DenBaars 《Journal of Electronic Materials》2009,38(6):756-760
Inclined crystallographic planes of the wurtzite structure were investigated in comparison with the zincblende structure in
terms of surface geometry characteristics. The ball–stick model indicates that the semipolar surface possesses a surface polarity resembling the anion polarity, which agrees with the common experimental observations
of epitaxial growth preference for the cation-polarity surface over the surface. The wurtzite surface was found to share geometrical similarities with the zincblende {100} surface uniquely among the possible semipolar
planes. This finding encourages epitaxial growth on the plane of wurtzite semiconductors, e.g., GaN, with the potential of avoiding atomic step formations typically associated with
off-axis crystallographic planes. 相似文献
8.
T. Nishihara M. Shinohara O. Ishiyama F. Ohtani M. Yoshimoto T. Maeda H. Koinuma 《Journal of Electronic Materials》1996,25(5):667-670
The topmost atom of InP (001) surfaces, which were annealed at temperatures between 300 and 550°C or sputtered with 1 keV
Ar+ at 300°C in ultra high vacuum, has been directly identified by means of coaxial impact collision ion scattering spectroscopy
(CAICISS). Time-of-flight spectra of the annealed InP (001) surface exhibited both In and P peaks in both
azimuth and in [100] azimuth, which revealed that the topmost layer of annealed InP (001) was comprised of In-terminated
and P-terminated surfaces. On the other hand, time-of-flight spectrum of the InP (001) sputtered at 300°C revealed only an
In peak in
azimuth and revealed both In and P peaks in [100] azimuth. This result indicates that the topmost layer on the Ar+-sputtered InP (001) surface was completely terminated by In atoms. Furthermore, we indicate that surface damage induced by
this sputtering treatment is little. The azimuthal depen-dence of CAICISS intensity scattered from In and P showed twofold
symmetry with respect to [100] direction, which originated from the zinc-blende structure. 相似文献
9.
Creep behavior of eutectic Sn-Cu lead-free solder alloy 总被引:3,自引:0,他引:3
Tensile creep behavior of precipitation-strengthened, tin-based eutectic Sn-0.7Cu alloy was investigated at three temperatures
ranging from 303–393 K. The steady-state creep rates cover six orders of magnitude (10−3−10−8 s−1) under the stress range of σ/E=10−4−10−3. The initial microstructure reveals that the intermetallic compound Cu6Sn5 is finely dispersed in the matrix of β-Sn. By incorporating a threshold stress, σ
th, into the analysis, the creep data of eutectic Sn-Cu at all temperatures can be fitted by a single straight line with a slope
of 7 after normalizing the steady-state creep rate and the effective stress, indicating that the creep rates are controlled
by the dislocation-pipe diffusion in the tin matrix. So the steady-state creep rate,
, can be expressed as
exp
, where Qc is the activation energy for creep, G is the temperature-dependent shear modulus, b is the Burgers vector, R is the universal
gas constant, T is the temperature, σ is the applied stress, A is a material-dependent constant, and
, in which σ
OB is the Orowan bowing stress, and kR is the relaxation factor.
An erratum to this article is available at . 相似文献
10.
Surface Morphology and Defect Formation Mechanisms for HgCdTe (211)B Grown by Molecular Beam Epitaxy 总被引:1,自引:0,他引:1
Yong Chang C.R. Becker C.H. Grein J. Zhao C. Fulk T. Casselman R. Kiran X.J. Wang E. Robinson S.Y. An S. Mallick S. Sivananthan T. Aoki C.Z. Wang D.J. Smith S. Velicu J. Zhao J. Crocco Y. Chen G. Brill P.S. Wijewarnasuriya N. Dhar R. Sporken V. Nathan 《Journal of Electronic Materials》2008,37(9):1171-1183
The surface morphology and crystallinity of HgCdTe films grown by molecular beam epitaxy (MBE) on both CdZnTe and CdTe/Si
(211)B substrates were characterized using atomic force microscopy (AFM), as well as scanning (SEM) and transmission (TEM)
electron microscopy. Crosshatch patterns and sandy-beach-like morphologies were commonly found on MBE (211) HgCdTe epilayers
grown on both CdZnTe and CdTe/Si substrates. The patterns were oriented along the , , and directions, which were associated with the intersection between the (211) growth plane and each of the eight equivalent HgCdTe
slip planes. This was caused by strain-driven operation of slip in these systems with relative large Schmid factor, and was
accompanied by dislocation formation as well as surface strain relief. Surface crater defects were associated with relatively
high growth temperature and/or low Hg flux, whereas microtwins were associated with relatively low growth temperature and/or
high Hg flux. AFM and electron microscopy were used to reveal the formation mechanisms of these defects. HgCdTe/HgCdTe superlattices
with layer composition differences of less than 2% were grown by MBE on CdZnTe substrates in order to clarify the formation
mechanisms of void defects. The micrographs directly revealed the spiral nature of growth, hence demonstrating that the formation
of void defects could be associated with the Burton, Cabrera, and Frank (BCF) growth mode. Void defects, including microvoids
and craters, were caused by screw defect clusters, which could be triggered by Te precipitates, impurities, dust, other contamination
or flakes. Needle defects originated from screw defect clusters linearly aligned along the directions with opposite Burgers vector directions. They were visible in HgCdTe epilayers grown on interfacial superlattices.
Hillocks were generated owing to twin growth of void or needle defects on (111) planes due to low growth temperature and the
corresponding insufficient Hg movement on the growth surface. Therefore, in addition to nucleation and growth of HgCdTe in
the normal two-dimensional layer growth mode, the BCF growth mode played an important role and should be taken into account
during investigation of HgCdTe MBE growth mechanisms. 相似文献
11.
Maskless Lateral Epitaxial Growth of Gallium Nitride Using Dimethylhydrazine as a Nitrogen Precursor
Lateral epitaxial growth (LEG) is a key technology to improve the lifetime of III-V nitride-based laser diodes (LDs) by reducing
the dislocation density in the materials. To increase the area of low dislocation density, the lateral growth rate needs to
be increased. In addition, suppression of the vertical growth is strongly desired to avoid unnecessarily thick growth, which
would result in cracks in the epitaxial film. This paper reports the maskless LEG of GaN with extremely high lateral-to-vertical
growth rate ratio using dimethylhydrazine as a nitrogen precursor. The lateral growth only occurs from the sidewalls of the
etched mesa stripes without any dielectric masks. The lateral growth rate toward the direction is extremely high, as high as 10 μm/h, while no vertical growth is observed on the top of unmasked mesa. The cross-sectional transmission electron microscopic
image shows that the threading dislocations in the wing region extend only toward the lateral direction. Note that almost smooth coalescence between the wing regions is confirmed by atomic force microscopy. X-ray diffraction
measurements reveal that this maskless LEG drastically improves the crystallographic twist down to 97 arc-s, which is as comparably
low as that of a free-standing GaN substrate. The presented maskless LEG is advantageous for optical device applications. 相似文献
12.
Lawrence H. Friedman 《Journal of Electronic Materials》2007,36(12):1546-1554
Heteroepitaxial self-assembled quantum dots (SAQDs) will allow breakthroughs in electronics and optoelectronics. SAQDs are
a result of Stranski–Krastanow growth, whereby a growing planar film becomes unstable after an initial wetting layer is formed.
Common systems are and For applications, SAQD arrays need to be ordered. The roles of crystal anisotropy, random initial conditions and thermal
fluctuations in influencing SAQD order during early stages of SAQD formation are studied through a simple stochastic model
of surface diffusion. Surface diffusion is analyzed through a linear and perturbatively non-linear analysis. The role of crystal
anisotropy in enhancing SAQD order is elucidated. It is also found that SAQD order is enhanced when the deposited film is
allowed to evolve at heights near the critical wetting surface height that marks the onset of non-planar film growth. 相似文献
13.
Kenji Monden 《Journal of Electronic Materials》2007,36(12):1691-1696
The creep properties of tin-based, lead-free solders, Sn-3.0Ag-0.5Cu and Sn-7.5Zn-3.0Bi, were investigated for the temperature
range from 298 K to 398 K. The creep rupture time decreases with increasing initial stress and temperature. The Omega method
is applied to the analysis of the solder creep curves. The creep rate is expressed by the following formula: , where and Ω are experimentally determined. The parameter , the imaginary initial strain rate, increases with increasing initial stress and temperature. The parameter Ω is temperature dependent, but less dependent on the initial stress. The apparent activation energy for is 108 kJ/mol in Sn-3.0Ag-0.5Cu and 83 kJ/mol in Sn-7.5Zn-3.0Bi. These values are close to the activation energy for the
lattice diffusion of tin. The creep rupture time is calculated using the parameters and Ω. The calculated creep rupture time is in good agreement with the measured creep rupture time. 相似文献
14.
Chung-Chieh Yang Chia-Feng Lin Jen-Hao Chiang Hsun-Chih Liu Chun-Min Lin Feng-Hsu Fan Chung-Ying Chang 《Journal of Electronic Materials》2009,38(1):145-152
InGaN-based light-emitting diodes (LEDs) were fabricated to have a higher light extraction through the photoelectrochemical
(PEC) mesa shaping process. After the PEC selective wet oxidation and wet etching processes, stable and controllable crystallographic
etching planes were formed as p-type GaN {} planes and n-type GaN {} planes included at an angle of 27 deg. The ever-present cone-shaped structure of a PEC-treated LED has a larger light scattering
area and higher light extraction cones on the mesa sidewall, as analyzed by microphotoluminescence and light output power
measurement. This cone-shaped-sidewall LED has a higher light output power and a larger divergence angle compared with a conventional
LED measured in an LED chip form. 相似文献
15.
Interfacial reactions of Y and Er thin films on both (111)Si and (001)Si have been studied by transmission electron microscopy
(TEM). Epitaxial rare-earth (RE) silicide films were grown on (111)Si. Planar defects, identified to be stacking faults on
planes with 1/6
displacement vectors, were formed as a result of the coalescence of epitaxial silicide islands. Double-domain epitaxy was
found to form in RE silicides on (001)Si samples resulting from a large lattice mismatch along one direction and symmetry
conditions at the silicide/(001)Si interfaces. The orientation relationships are [0001]RESi2−x//
Si,
RESi2−x//(001)Si and [0001]RESi2−x/
Si,
RESi2−x//(001)Si. The density of staking faults in (111) samples and the domain size in (001) samples were found to decrease and
increase with annealing temperature, respectively. 相似文献
16.
P. Kale P. Padmini J. Dou L. Navarrete M. Shamsuzzoha R. Schad R. K. Pandey 《Journal of Electronic Materials》2007,36(9):1224-1228
The ilmenite–hematite (1 − x) FeTiO3 · xFe2O3 solid solution system is considered to be a novel material for spin-electronics, microelectronics, high-temperature electronics,
and radhard electronics. This paper focuses on thin films of composition x = 0.33 grown on (100) MgO single-crystal substrates using pulsed-laser deposition (PLD) under different argon–oxygen mixtures.
The surface of the MgO was found to possess MgO2 crystals, yielding an orientation relationship, [001] MgO ∥ [011] MgO2 and (00)MgO ∥ (10) MgO2. The structural characterizations show that the films are crystalline and homogeneous without any secondary phase. The films
show a weak and inclined (110) growth epitaxy. A bandgap of 3.4–3.7 eV was obtained for these films from optical measurements carried out in the UV–visible
region. Electrical measurements confirmed the semiconducting behavior. However, the resistivity was found to increase substantially
on the slightest addition of oxygen into the chamber. 相似文献
17.
The ultraviolet (UV) photoelectric characteristics of transitional metal (Cu) doped ZnO nanowires produced by the self-catalytic
vapor–liquid–solid (VLS) method were investigated by performing a series of photoconduction and time-resolved measurements.
The photocurrent voltage characteristics obtained on the nanowires configured as two-terminal metal–semiconductor–metal photodetectors
exhibited a nonmonotonic behavior attributed to the interplay of several limiting mechanisms: Schottky contacts and trapping/detrapping
effects that take place at low and intermediate (pre-avalanche) bias regimes, respectively. In the intermediate biases, the
photocurrent was power-law dependent, i.e., changed with voltage as
and for excitation wavelengths of 365 nm, 302 nm, and 254 nm, respectively. The dependence of the exponent on the wavelength
of the light is analyzed and explained based on the detailed consideration of the contribution of different deep-defect Cu
levels formed within the band gap of ZnO. The study will be important to those working in the area of ZnO-based nanophotodetectors,
optical switches, and sensors. 相似文献
18.
We present evidence that it is the presence or absence of atomic terraces with a specific crystallographic orientation on
the (102) Al2O3 surface that promotes growth of single-crystal (001) CeO2 films over polycrystalline (111) CeO2 films. The CeO2 film nucleates so that the [010] and [100] directions of the film align parallel and perpendicular to the terrace edges.
In the absence of terraces, multidomain (111) CeO2 films result in which the in-plane orientation of the two domains are rotated by 85.71°, so that a [110] CeO2 direction aligns parallel to either the or Al2O3 direction. 相似文献
19.
A Fully Integrated, Low Noise and Low Power BiCMOS Front-end Readout System for Capacitive Detectors 总被引:1,自引:0,他引:1
Chaoying-Christine Guo Philippe Schmitt Grzegorz Deptuch Yongcai-Yann Hu 《Analog Integrated Circuits and Signal Processing》2001,28(3):211-223
Bipolar transistors are interesting for low noise front-end readout systems when high speed and low power consumption are required. This paper presents a fully integrated, low noise front-end design for the future Large Hadron Collider (LHC) experiments using the radiation hard SOI BiCMOS process. In the present prototype, the input-referred Equivalent Noise Charge (ENC) of 990 electrons (rms) for 12 pF detector capacitance with a shaping time of 25 ns and power consumption of 1.4 mW/channel has been measured. The gain of this front-end is 90 mV/MIP (Minimum Ionisation Particle: 1
fC) with non-linearity of less than 3% and linear input dynamic range is
MIP. These results are obtained at room temperature and before irradiation. The measurements after irradiations by high intensity pion beam with an integrated flux of
pions/cm2 are also presented in this paper. 相似文献
20.
The results of an ab?initio modelling of aluminium substitutional impurity (\({\hbox {Al}}_{\rm Ge}\)), aluminium interstitial in Ge [\({\hbox {I}}_{\rm Al}\) for the tetrahedral (T) and hexagonal (H) configurations] and aluminium interstitial-substitutional pairs in Ge (\({\hbox {I}}_{\rm Al}{\hbox {Al}}_{\rm Ge}\)) are presented. For all calculations, the hybrid functional of Heyd, Scuseria, and Ernzerhof in the framework of density functional theory was used. Defects formation energies, charge state transition levels and minimum energy configurations of the \({\hbox {Al}}_{\rm Ge}\), \({\hbox {I}}_{\rm Al}\) and \({\hbox {I}}_{\rm Al}{\hbox {Al}}_{\rm Ge}\) were obtained for ?2, ?1, 0, \(+\)1 and \(+\)2 charge states. The calculated formation energy shows that for the neutral charge state, the \({\hbox {I}}_{\rm Al}\) is energetically more favourable in the T than the H configuration. The \({\hbox {I}}_{\rm Al}{\hbox {Al}}_{\rm Ge}\) forms with formation energies of ?2.37 eV and ?2.32 eV, when the interstitial atom is at the T and H sites, respectively. The \({\hbox {I}}_{\rm Al}{\hbox {Al}}_{\rm Ge}\) is energetically more favourable when the interstitial atom is at the T site with a binding energy of 0.8 eV. The \({\hbox {I}}_{\rm Al}\) in the T configuration, induced a deep donor (\(+\)2/\(+1\)) level at \(E_{\mathrm {V}}+0.23\) eV and the \({\hbox {Al}}_{\rm Ge}\) induced a single acceptor level (0/?1) at \(E_{\mathrm {V}}+0.14\) eV in the band gap of Ge. The \({\hbox {I}}_{\rm Al}{\hbox {Al}}_{\rm Ge}\) induced double-donor levels are at \(E_{\rm V}+0.06\) and \(E_{\rm V}+0.12\) eV, when the interstitial atom is at the T and H sites, respectively. The \({\hbox {I}}_{\rm Al}\) and \({\hbox {I}}_{\rm Al}{\hbox {Al}}_{\rm Ge}\) exhibit properties of charge state-controlled metastability. 相似文献