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1.
Masakazu Katsuno Noboru Ohtani Tatsuo Fujimoto Hirokatsu Yashiro 《Journal of Electronic Materials》2005,34(1):91-95
The effect of off-orientation growth has been investigated in terms of stacking fault formation during physical vapor transport
(PVT) growth of silicon carbide (SiC) single crystals on the (11
0) seed crystal surface. Occurrence of stacking fault formation is largely dependent on the direction of off-orientation,
and basal plane stacking fault density is significantly reduced by growing the crystals on a (11
0) seed crystal off-oriented toward 〈0001〉. The density of the basal plane stacking faults rapidly decreases from 100–150
cm−1 to ∼10 cm−1 as the degree of off-orientation is increased from 0 to 10 deg. The results are interpreted in the framework of microscopic
facet formation during PVT growth, and the introduction of off-orientation of seed crystal is assumed to prevent (01
0) and (10
0) microfacet formation on the (11
0) growing surface through modification of the surface growth kinetics and to suppress the stacking fault formation.
An erratum to this article is available at . 相似文献
2.
Feng Wu Shai Zamir Boris Meyler Joseph Salzman Yuval Golan 《Journal of Electronic Materials》2003,32(1):23-28
Transmission electron microscopy (TEM), atomic force microscopy (AFM), and photoluminescence (PL) spectroscopy were used in
order to study the microstructure and optical properties of GaN films grown by metal-organic chemical vapor deposition (MOCVD)
on c-plane sapphire by lateral confined epitaxy (LCE). In this method, the substrate is etched prior to growth to form uniform
mesas separated by trenches for laterally restricting growth area. As previously observed for LCE GaN on Si(111), the density
of threading dislocations was significantly reduced in the areas close to the edge of mesas due to the lateral propagation
of the dislocations. Hence, the overall material quality improves with decreasing mesa size, which is consistent with the
observed increase in photoluminescence band edge peak intensity. Electron diffraction indicated ∼1° rotation about the [
] axis between the mesa and trench material, which was also observed in the image contrast of these two regions with g=
. Additionally, LCE samples prepared in [
] and [
] cross sections were used for comparing the growth rates in these two perpendicular directions. As theoretically expected,
growth in the [
] direction appears to proceed considerably faster than that in the [% MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn%
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fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaaGymaiaaig% daceaIYaGbaebacaaIWaaaaa!38D1!\[11\bar 20\]] direction. 相似文献
3.
4.
The growth of Cu-Sn intermetallic compounds (IMCs) at the molten Pb-Sn solder/Cu interface was studied over a range of temperatures
and for a range of solder compositions. Strong peaks of
and
planes of η-phase (Cu6Sn5) were detected by x-ray diffraction when the Sn content was high. In the low Sn solder (27Sn-73Pb), the η-phase peaks were
absent at the two high temperatures, but the (2 12 0) peak of the ε-phase (Cu3Sn) was prominent. A texture was detected in both layers in
and (002) pole figures constructed for the η phase and ε phase, respectively. The growth directions were identified to be
〈101〉 and 〈102〉 for the η phase and 〈102〉 and 〈031〉 for the ε phase, normal to the Cu surface. The growth direction does not
change with the morphology and the thickness of the IMC layer. The morphology of the η layer varied gradually from a cellular
film with a rugged interface to a dense film with a scalloped interface as the Pb content, temperature, and reaction time
increased. The ε layer was always dense and nearly planar. 相似文献
5.
Orientation dependent etching of photolithographically patterned
GaP was investigated using solutions of HCl:CH3COOH:H2O2. The pattern was prepared using standard ultraviolet lithography and was a two-dimensional grid with an 18 μm repeat, consisting
of 15 μm squares separated by 3 μm spaces. The mask sides were aligned along the
and
directions. Under appropriate etching conditions, high quality arrays of pyramids were prepared. These pyramids were defined
by
,
and
facets. It was shown that the etching process depended on the degree of solution aging after initial mixing. For a freshly
prepared solution, the etching rate showed an inverse dependence on time. For short etching times (below 5 min), an intermediate
etching profile was followed, while for long times (greater than 5 min) etching was kinetically controlled. We demonstrated
that controlled etching at extremely low rates (0.1–0.5 μm/min) is feasible with this new approach. 相似文献
6.
Seoyong Ha Noel T. Nuhfer Gregory S. Rohrer Marc de Graef Marek Skowronski 《Journal of Electronic Materials》2000,29(7):L5-L8
Transmission electron microscopy (TEM) and KOH etching have been used to study the dislocation structure of 4H SiC wafers
grown by physical vapor transport. A new type of threading dislocation arrays was observed. Rows of etch pits corresponding
to dislocation arrays were observed in vicinity of micropipes, misoriented grains and polytypic inclusions at the periphery
of the boules and extended along the
directions. Plan view conventional and high resolution TEM showed that the arrays consisted of dislocations threading along
the c-axis with Burgers vectors having edge components of the a/3
type. The Burgers vectors were parallel to the corresponding arrays. The dislocation arrays were interpreted as slip bands
formed by dislocation glide in the prismatic slip system
of hexagonal SiC during post-growth cooling. 相似文献
7.
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
8.
Roskowski A. M. Preble E. A. Einfeldt S. Miraglia P. M. Davis R. F. 《Journal of Electronic Materials》2002,31(5):421-428
High-resolution x-ray diffraction (XRD) and atomic force microscopy (AFM) of pendeo-epitaxial (PE) GaN films confirmed transmission
electron microscopy (TEM) results regarding the reduction in dislocations in the wings. Wing tilt ≤0.15° was due to tensile
stresses in the stripes induced by thermal expansion mismatch between the GaN and the SiC substrate. A strong D°X peak at
≈3.466 eV (full-width half-maximum (FWHM) ≤300 μeV) was measured in the wing material. Films grown at 1020°C exhibited similar
vertical [0001] and lateral [11
0] growth rates. Increasing the temperature increased the latter due to the higher thermal stability of the GaN(11
0). The (11
0) surface was atomically smooth under all growth conditions with a root mean square (RMS)=0.17 nm. 相似文献
9.
The effect of substrate misorientation on phase separation in Ga1−xInxAsySb1−y nominally lattice matched to GaSb is reported. The layers were grown at 575°C by organometallic vapor phase epitaxy on vicinal
(001) GaSb substrates, miscut
or (101). Ga1−xInxAsySb1−y (x ~ 0.1, ~ 0.09) layers, which have 300-K photoluminescence (PL) peak emission at ~2.1 μm, grow stepbunched and exhibit
minimal phase separation. The full width at half maximum of 4-K PL spectra is slightly smaller at 7 meV for layers grown on
substrates miscut toward
compared to 9 meV for layers grown on substrates miscut toward
and (101). Ga1−xInxAsySb1−y layers with higher alloy composition (0.16≤x≤0.19, 0.14≤y≤0.17), which have 300-K PL peak emission at ~2.4 μm, have significant
phase separation. These layers are characterized by increased lattice constant variations and epitaxial tilt, broad PL spectra
with significant band tailing, and strong contrast modulation in transmission electron microscopy. The degree of decomposition
depends on substrate miscut direction: Ga1−xInxAsySb1−y layers grown on (001)
substrates are more homogeneous than those grown on (001)
and (001)2°→(101) substrates. The results are attributed to the smaller adatom diffusion length on substrates miscut toward
. 相似文献
10.
The bias-enhanced nucleation (BEN) technique in hot-filament chemical vapor deposition (HF-CVD) has been applied to single
crystalline 6H-SiC substrates for the deposition of oriented diamond. The results of scanning electron microscopy (SEM) showed
that on (000
) face not only oriented diamond with relationship (111) Dia.//(000
)6H-SiC and 〈110〉Dia.//(11
0)6H-SiC, but also high nucleation density (>109 cm−2) have been achieved. In the case of deposition on (0001) face of 6H-SiC under the same experimental conditions, although
the nucleation density of diamond was enhanced, however, oriented diamond was not found. Diamond nucleation density is higher
on (0001) face than that on (000
) face. The differences in diamond oriented nucleation and nucleation density on these two faces are attributed to the difference
of their specific free surface energy. The experimental results have shown that the 6H-SiC substrate surfaces are etched by
the accelerated H-ions during BEN process, and many micro-triangular crystals with the faces of the kind {01
4} are formed on the substrate surface. Diamonds nucleate on the top of the micro-triangular crystals. Micro-Raman spectrum
shows a strong feature of diamond crystals at 1334 cm−1. 相似文献
11.
To investigate the potential benefits of compositional grading for dislocation control in CdTe/Si growth, Cd1−xZnxTe buffer layers with x graded smoothly from 1 to 0 have been deposited on Si (211) surfaces. Growth has been characterized
using reflection high-energy electron diffraction (RHEED), x-ray diffraction (XRD), and etch pit density measurements. XRD
showed an increase in rocking curve full-width at half-maximum (FWHM) and global lattice tilt with decreasing x values. Tilt
was also observed to increase as buffer growth temperature was increased. Final surface dislocation densities did not decrease
below 7×106 cm−2. EPD surface dislocation measurements showed reduced dislocation densities and dislocation clustering along the
and
lines for CdTe cap layers grown on partially graded Cd1−xZnxTe buffer layers with slow compositional grading rates. Samples grown with faster grading rates showed higher final EPD values,
with dislocations clustering along the
and
lines. 相似文献
12.
13.
Hao Lee Weidong Yang Peter C. Sercel A. G. Norman 《Journal of Electronic Materials》1999,28(5):481-485
We have determined the shape of InAs quantum dots using reflection high energy electron diffraction. Our results indicate
that self-assembled InAs islands possess a pyramidal shape with {136} bounding facets. This shape is characterized by C2v
symmetry and a parallelogram base, which is elongated along the
direction. Cross-sectional transmission electron microscopy images taken along the [110] and
directions as well as atomic force microscopy images strongly support the {136} shape. Furthermore, polarization-resolved
photoluminescence spectra show strong in-plane anisotropy, with emission predominantly polarized along the
direction, consistent with the proposed quantum dot shape. 相似文献
14.
Atomic hydrogen assisted molecular beam epitaxy on patterned GaAs (311)A substrates: Formation of highly uniform quantum-dot arrays 总被引:2,自引:0,他引:2
Richard Nötzel Manfred Ramsteiner Zhichuan Niu Achim Trampert Lutz Däweritz Klaus H. Ploog 《Journal of Electronic Materials》1998,27(1):38-42
The idea of combining self-organized growth with growth on patterned substrates to produce new types of nanostructures in
a controlled manner is realized in atomic hydrogen assisted molecular beam epitaxy (MBE) on patterned GaAs (311)A substrates.
In conventional MBE on patterned substrates mesa stripes along [01
] develop a fast growing sidewall to form quasi-planar lateral quantum wires having a smooth, convex curved surface profile.
In atomic hydrogen assisted MBE, the surface naturally develops quasiperiodic one-dimenional step arrays by step bunching
along [
33], i.e., perpendicular to the wire direction with a lateral periodicity around 40 nm. The step array is maintained over
the curved sidewall without displacement. Thus, a dense array of dotlike nanostructures is realized with precise control of
the position on the substrate surface. High uniformity of the dot array is revealed in micro-photoluminescence spectroscopy
with the emission dominated by one single sharp line. 相似文献
15.
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
16.
The polarization of the photoluminescence (PL) of self-assembled CdSe quantum dots (QDs), grown by metalorganic chemical vapor
phase deposition, was measured. From the (001) surface, the PL was found preferentially polarized in the
direction, while from the
cleaved surface in the [001] direction. The polarization of PL depends strongly on the ZnSe capping layer thickness and the
PL energy. With an increase in ZnSe coverage, the intensity ratio
was found to increase first, then decrease after the coverage is thicker than a critical value. Moreover, such a critical
thickness is smaller for larger QDs (lower PL energies). Possible origins of the PL polarization are discussed. We suggest
that besides the quantum confinement effects, the strain field in the QDs also plays an essential role in the observed polarization
of PL. 相似文献
17.
The mechanical properties of pure and doped (Fe, Zn, Sn) InP single crystals have been investigated in the temperature range
293–600 K. It is shown that impurity hardening (increase in microhardness) is much more pronounced at high temperatures than
at room temperature because of the retardation of moving dislocations by impurities, which is strongest at high temperatures.
Appreciable scratch hardness anisotropy on the (001) face of the experimental crystals at 293 K was observed. It decreases
rapidly as the temperature increases in the interval 293–600 K. It is shown that the [110] and
directions on the (001) face of the experimental crystals are nonequivalent. The observed phenomena are explained by the
different contributions of the two mechanisms of plastic deformation: slip and twinning in the process of scratch formation
along the 〈100〉 and 〈110〉 directions, and along the [110] and
directions.
Fiz. Tekh. Poluprovodn. 31, 243–246 (February 1997) 相似文献
18.
Ok-Hyun Nam Tsvetanka S. Zheleva Michael D. Bremser Robert F. Davis 《Journal of Electronic Materials》1998,27(4):233-237
Lateral epitaxial growth and coalescence of GaN regions over SiO2 masks previously deposited on GaN/AlN/6H-SiC(0001) substrates and containing 3 μm wide rectangular windows spaced 7 μm apart
have been achieved. The extent and microstructural characteristics of these regions of lateral overgrowth were a complex function
of stripe orientation, growth temperature, and triethylgallium (TEG) flow rate. The most successful growths were obtained
from stripes oriented along 〈1
00〉 at 1100°C and a TEG flow rate of 26 μmol/min. A density of ∼109 cm−2 threading dislocations, originating from the underlying GaN/AlN interface, were contained in the GaN grown in the window
regions. The overgrowth regions, by contrast, contained a very low density of dislocations. The surfaces of the coalesced
layers had a terrace structure and an average root mean square roughness of 0.26 nm. 相似文献
19.
P. Wu J. Zhong N. W. Emanetoglu Y. Chen S. Muthukumar Y. Lu 《Journal of Electronic Materials》2004,33(6):596-599
Zinc oxide (ZnO) possesses many interesting properties, such as a wide energy bandgap, large photoconductivity, and high excitonic
binding energy. Chemical-vapor-deposition-grown ZnO films generally show n-type conductivity. A compensation doping process
is needed to achieve piezoelectric ZnO, which is needed for surface acoustic wave (SAW), bulk acoustic wave, and micro-electromechanical
system devices. In this work, a gas-phase diffusion process is developed to achieve piezoelectric (11
0) ZnO films. Comparative x-ray diffraction (XRD) and scanning electron microscopy (SEM) measurements confirmed that high
crystal quality and good surface morphology were preserved after diffusion. Photoluminescence (PL) measurements show a broad
band emission with a peak wavelength at ∼580 nm, which is associated with Li doping. The SAW, including both Rayleigh-wave
and Love-wave modes, is achieved along different directions in piezoelectric (11
0) ZnO films grown on an r-plane sapphire substrate. 相似文献
20.
Creep-rupture properties of lead-free Sn-3.5Ag-based alloys with varying amount of Cu were investigated using rolled and heat-treated
dog-bone-shaped specimens. Nominal compositions of added copper were 0 wt.%, 0.5 wt.%, 0.75 wt.%, 1.0 wt.%, and 1.5 wt.%.
During creep tests, the matrix hardness dropped significantly, and the minimum strain rates (
) were lowest for the 0.75Cu specimens. The stress exponents (n) of
were usually around 4, with the exception of the 0.5Cu and 0.75Cu alloys, which showed somewhat higher values of n. Fractographic
analyses revealed typical creep rupture by the nucleation and growth of cavities in the matrix except the 1.5Cu specimens,
which showed cavity nucleation at brittle Cu6Sn5 particles. 相似文献