共查询到20条相似文献,搜索用时 0 毫秒
1.
Thomas Gehrke Kevin J. Linthicum Edward Preble Pradeep Rajagopal Carsten Ronning Christian Zorman Mehran Mehregany Robert F. Davis 《Journal of Electronic Materials》2000,29(3):306-310
Pendeo-epitaxy (PE)1 from raised, [0001] oriented GaN stripes covered with silicon nitride masks has been employed for the growth of coalesced
films of GaN(0001) with markedly reduced densities of line and planar defects on Si(111)-based substrates. Each substrate
contained previously deposited 3C-SiC(111) and AlN(0001) transition layers and a GaN seed layer from which the stripes were
etched. The 3C-SiC transition layer eliminated chemical reactions between the Si and the NH3 and the Ga metal from the decomposition of triethylgallium. The 3C-SiC and the GaN seed layers, each 0.5 μm thick, were also
used to minimize the cracking and warping of the GaN/SiC/silicon assembly caused primarily by the stresses generated on cooling
due to the mismatches in the coefficients of thermal expansion. Tilting in the coalesced GaN epilayers of 0.2° was confined
to areas of lateral overgrowth over the masks; no tilting was observed in the material suspended above the trenches. The strong,
low-temperature PL band-edge peak at 3.456 eV with a FWHM of 17 meV was comparable to that observed in PE GaN films grown
on AlN/6H-SiC(0001) substrates. 相似文献
2.
M. A. L. Johnson Zhonghai Yu J. D. Brown N. A. El-Masry J. W. Cook Jr. J. F. Schetzina 《Journal of Electronic Materials》1999,28(3):295-300
Traditional epitaxial growth of GaN by metalorganic vapor phase epitaxy (MOVPE) on mismatched substrates such as sapphire
or SiC produces a columnar material consisting of many hexagonal grains ∼0.2–1.0 μm in diameter. The epitaxial-lateral-overgrowth
(ELO) process for GaN creates a new material: single-crystal GaN. We have studied the ELO process for GaN grown by MOVPE in
a vertical flow rotating substrate reactor. Characterization consisted of plan-view SEM and vertical-cross-section TEM studies,
which revealed a large reduction in dislocation density in the overgrown regions of the GaN. Panchromatic and monochromatic
cathodoluminescence images and spectra were used to study the spatial variation of the optical properties within the GaN ELO
samples. The effects of growth temperature and stripe material on the overgrown layers were examined. Through the use of a
higher substrate temperature during growth and the use of a SiNx stripe material, the overgrown crystal shape has a smooth 2D top surface with vertical sidewalls. Applying a second ELO step,
rotated by 60°, over a fully coalesced ELO layer yields a further reduction of defects in GaN overgrown surfaces. 相似文献
3.
In-Tae Bae Tae-Yeon Seong Young Ju Park Eun Kyu Kim 《Journal of Electronic Materials》1999,28(7):873-877
Detailed transmission electron microscope (TEM) and transmission electron diffraction (TED) examination has been performed
on organometallic vapor phase epitaxial GaN layers grown on (001) GaAs substrate to investigate microstructures and phase
stability. TED and TEM results exhibit the occurrence of a mixed phase of GaN. The wurtzite (α) phase grains are embedded
in the zinc-blende (β) phase matrix. It is shown that there are two types of the wurtzite GaN phase, namely, the epitaxial
wurtzite and the tilted wurtzite. The tilted wurtzite grains are rotated some degrees ranging from ∼5° to ∼35° regarding the
GaAs substrate. A simple model is presented to describe the occurrence of the mixed phases and the two types of the wurtzite
phase. 相似文献
4.
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
5.
G. Attolini P. Franzosi C. Pelosi L. Lazzarini G. Salviati 《Journal of Electronic Materials》1994,23(2):153-158
Highly mismatched GaAs epitaxial layers with thickness ranging from 15 nm to 7 μm have been grown on InP substrates by atomospheric
pressure metalorganic vapor phase epitaxy. Layers thinner than 30 nm exhibited 3-D growth mechanism; in the thicker layers,
the islands coalesced and then the growth followed the layer by layer mechanism. The elastic strain and the extended defects
have been studied by high resolution x-ray diffraction and transmission electron microscopy, respectively. The common observation
of planar defects, misfit, and threading dislocations in the layers has been confirmed. The results on the elastic strain
release have been discussed on the basis of the equilibrium theory. 相似文献
6.
Joon-Hyung Kim Tae-Yeon Seong N. J. Mason P. J. Walker 《Journal of Electronic Materials》1998,27(5):466-471
The initial nucleation of GaSb on (001) GaAs substrates by metalorganic vapor phase epitaxy has been investigated using transmission
electron microscopy (TEM) and high resolution electron microscopy (HREM). TEM results showed that the GaSb islands experience
a morphological transition as the growth temperature increases. For growth at 520°C, the islands are longer along the [110]
direction; at 540°C, they are nearly square, and at 560°C, they are longer along the
direction. Possible mechanisms are proposed to describe such a transition. TEM and HREM examination showed that lattice misfit
relaxation mechanisms depend on the growth temperature. For the sample grown at 520°C, the lattice mismatch strain was accommodated
mainly by 90° dislocations; for the sample grown at 540°C, the misfit strain was relieved mostly by 90° dislocations with
some of 60° dislocations, and for the sample grown at 560°C, the strain was accommodated mainly by 60° dislocations which
caused a local tilt of the GaSb islands with respect to the GaAs substrate. The density of threading dislocations was also
found to be dependent on the growth temperature. Mechanisms are proposed to explain these phenomena. 相似文献
7.
We studied the bandgap energy shift by varying the SiO2 mask width in selective MOVPE growth of InAIGaAs with almost no polycrystals on the masks. We found that the photoluminescence
(PL) peak shifts toward the longer wavelength with wider mask width and narrower mesa width, where the In content is enhanced,
and observed a maximum PL peak wavelength shift of 170 nm. 相似文献
8.
A. E. Wickenden L. B. Rowland K. Doverspike D. K. Gaskill J. A. Freitas D. S. Simons P. H. Chi 《Journal of Electronic Materials》1995,24(11):1547-1550
The silicon doping of n-type GaN using disilane has been demonstrated for films grown on sapphire substrates by low pressure
organometallic vapor phase epitaxy. The binding energy of an exciton bound to a neutral Si donor has been determined from
low temperature (6K) photoluminescence spectra to be 8.6 meV. Nearly complete activation of the Si impurity atom in the GaN
lattice has been observed. 相似文献
9.
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
10.
M. Heuken C. V. Eichel-Streiber A. Behres B. Schineller K. Heime C. Mendorf G. Brockt H. Lakner 《Journal of Electronic Materials》1997,26(10):1221-1224
We investigated the growth of InPSb on GaSb or InAs by low pressure (20 mbar) metalorganic vapor phase epitaxy (MOVPE). Trimethylindium,
triethylantimony, and phosphine were used as starting materials. High resolution x-ray diffraction, photoluminescence at 10K,
Hall measurements at 300 and 77K as well as scanning electron microscopy and scanning tunneling electron microscopy investigations
were carried out to verify the layer properties. Lattice-matched InPSb layers on InAs substrate grown at 520°C show mirror-like
surfaces and sharp x-ray peaks. N-type doping of InP0.69Sb0.31 was carried out with H2S and p-type doping was achieved with DEZn. Maximum electron concentrations of 2×1019 cm−3 and hole concentrations exceeding 1018 cm−3 were obtained after annealing in N2 ambient. The thermal stability of InPSb was studied during annealing experiments carried out at 500°C up to 30 min. The compositional
integrity of the lattice proves to be stable and the InAs/InPSb interface can be improved. Multiple quantum well structures,
pn-junction diodes and the two-dimensional electron gas at the InPSb/InAs/InPSb quantum wells were investigated to demonstrate
the properties of the material. 相似文献
11.
H. Protzmann B. Wachtendorf O. Schoen D. Schmitz G. Strauch H. Juergensen 《Journal of Electronic Materials》1998,27(4):342-345
For the fabrication of epitaxial films of silicon carbide or the Group III nitrides, high growth temperatures (up to 1700°C)
and fast heating and cooling of the growth environment have been found to be necessary. A range of production systems meeting
these requirements has been designed with different loading capacities. In this paper, we present results from various machines
showing the high quality and excellent homogeneity obtainable for 3C-SiC on Si and on 6H-SiC, as well as GaN on sapphire. 相似文献
12.
The impact of nitridation and nucleation layer process conditions on morphology and electron transport in GaN epitaxial films 总被引:1,自引:0,他引:1
A. E. Wickenden D. D. Koleske R. L. Henry R. J. Gorman J. C. Culbertson M. E. Twigg 《Journal of Electronic Materials》1999,28(3):301-307
A systematic study has been performed to determine the characteristics of an optimized nucleation layer for GaN growth on
sapphire. The films were grown during GaN process development in a vertical close-spaced showerhead metalorganic chemical
vapor deposition reactor. The relationship between growth process parameters and the resultant properties of low temperature
GaN nucleation layers and high temperature epitaxial GaN films is detailed. In particular, we discuss the combined influence
of nitridation conditions, V/III ratio, temperature and pressure on optimized nucleation layer formation required to achieve
reproducible high mobility GaN epitaxy in this reactor geometry. Atomic force microscopy and transmission electron microscopy
have been used to study improvements in grain size and orientation of initial epitaxial film growth as a function of varied
nitridation and nucleation layer process parameters. Improvements in film morphology and structure are directly related to
Hall transport measurements of silicon-doped GaN films. Reproducible growth of silicon-doped GaN films having mobilities of
550 cm2/Vs with electron concentrations of 3 × 1017 cm−3, and defect densities less than 108 cm−2 is reported. These represent the best reported results to date for GaN growth using a standard two-step process in this reactor
geometry. 相似文献
13.
J. Giess J. E. Hails A. Graham G. Blackmore M. R. Houlton J. Newey M. L. Young M. G. Astles W. Bell D. J. Cole-Hamilton 《Journal of Electronic Materials》1995,24(9):1149-1153
It has been established that a compound present as an impurity in the propan-2-ol used in the preparation of GaAs (100) substrates
for the metalorganic vapor phase epitaxy growth of (Hg,Cd)Te has a marked effect on the crystalline perfection and surface
morphology of the resulting layers. In particular, the presence of this species, which contains Na, ensures that (i) the epitaxial
overgrowth is of (100) orientation without the need for ZnTe nucleation layers, and (ii) the density of pyramidal hillocks
on the surface can be reproducibly < 10 cm−2. 相似文献
14.
The growth rates of GaSb by metalorganic vapor phase epitaxy were studied as functions of growth temperatures and partial
pressures of precursors. A Langmuir-Hinshelwood model was used to explain the GaSb growth rate in the chemical reaction controlled
regime. The relationship between growth kinetics and epilayer qualities was discussed and properties of GaSb were obtained. 相似文献
15.
J. Söllner J. Schmoranzer H. Hamadeh B. Bollig E. Kubalek M. Heuken 《Journal of Electronic Materials》1995,24(11):1557-1561
ZnMgSSe heterostructures have been grown in a low-pressure metalorganic vapor phase epitaxy system with the precursors dimethylzinc
triethylamine, ditertiarybutylselenide, tertiarybutylthiol, and biscyclopentadienylmagnesium at 330°C and a total pressure
of 400 hPa. The optimization of the single layers was carried out by means of low temperature photoluminescence. Only the
near band edge emission was observable with negligible deep levels. The heterostructures consisting of a triple ZnSe quantum
well showed intense luminescence which hints at an effective carrier confinement. Scanning transmission electron microscopy
investigations of the heterostructures still showed structural detects since the layers were not lattice matched to the GaAs
substrate yet. 相似文献
16.
S. J. C. Irvine A. Stafford M. U. Ahmed A. Brown H. Kheyrandish 《Journal of Electronic Materials》1997,26(6):723-727
The first detailed comparison has been made of the metalorganic vapor phase epitaxy growth rates of CdTe, ZnTe, and ZnSe,
measured in situ with laser reflectometry. The comparison also includes the photo-assisted growth with visible radiation from
an argon ion laser. Using a standard Group II precursor (DMCd or DMZn.TEN) partial pressure of 1.5 × 10−4 atm, VI/II ratio of 1 and DIPM (M = Te, Se) the maximum growth rates are in the region of 10 to 15 AU/ s. Decrease in growth
rates of ZnTe at higher temperatures or higher laser powers have been attributed to the desorption from the substrate of unreacted
Te precursor. The behavior of DTBSe is quite different from DIPSe for both pyrolytic and photo-assisted growth. The maximum
growth rate is around 1 AU/ s with very little photo-enhancement, except at 300°C. Secondary ion mass spectroscopy analysis
of hydrogen concentration in the ZnSe layers shows high concentrations, up to 5.9 × 1019 atoms cm−3 for DTBSe grown ZnSe under pyrolytic conditions. These results show that the growth kinetics play an important part in the
incorporation of hydrogen and passivation of acceptor doped material. 相似文献
17.
F. Bugge A. Knauer S. Gramlich I. Rechenberg G. Beister J. Sebastian H. Wenzel G. Erbert M. Weyers 《Journal of Electronic Materials》2000,29(1):57-61
GaAs-based diode lasers for emission wavelengths between 800 nm and 1060 nm with AlGaAs-cladding and GaInP-waveguide layers
were grown by MOVPE. For wavelengths above 940 nm broad area devices with InGaAs QWs show state-of-the-art threshold current
densities. Ridge-waveguide lasers fabricated by selective etching achieve 200 mW CW monomode output powers. (In)GaAsP QW-based
diode lasers with an emitting wavelengths around 800 nm suffer from problems at the upper GaInP/AlGaAs interface. Asymmetric
structures with a lower AlGaAs/GaInP and an upper AlGaAs/AlGaAs waveguide not only avoid this interface but also offer better
carrier confinement. Such structures show very high slope efficiencies and a high T0. Maximum output powers of 7 W CW are obtained from 4 mm long devices. 相似文献
18.
InGaN layers were grown on GaN films by flow modulation epitaxy (FME) using the precursors trimethylgallium, trimethylindium,
and ammonia. The indium composition of the FME grown layers was generally lower than of films grown under the same conditions
in the continuous growth mode, but which had been of poor optical quality. The indium incorporation efficiency increased with
decreasing ammonia flush time, increasing ammonia flow during group-III injection, and increasing group-III precursor injection
time. Films grown under optimized conditions showed intense band edge related luminescence at room temperature up to a wavelength
of 465 nm. Atomic force microscopy investigations revealed a strong dependence of the surface morphology of the InGaN films
on the growth mode. 相似文献
19.
R. M. Lum M. L. Mc Donald E. M. Mack Williams M.D. F. G. Storz J. Levkoff 《Journal of Electronic Materials》1995,24(11):1577-1581
The influence of growth temperature on the composition of InGaAsP films grown by low pressure metalorganic vapor phase epitaxy
(MOVPE) is reported for quaternary (Q) alloys having bandgap wavelengths of λg = 1.1, 1.3, and 1.5 μn. Films with these different Q-compositions were deposited lattice matched to InP at a growth temperature
of 675°C. Subsequent growth experiments were then performed for each Q-composition in which the input gas flow rates were
kept the same and only the temperature changed in 25°C decrements down to 600°C. Photoluminescence (PL) and lattice mismatch
(LMM) measurements of the resulting films were used to determine the effect of growth temperature on film composition. The
PL data indicate a temperature shift in the PL wavelength of −1.8 nm/ °C for the 1.5Q composition, −2.9 nm/°C for 1.3Q, and
−4.3 nm/°C for 1.1Q. Negative shifts were also observed in LMM of −80 ppm/°C for 1.5Q, −150 ppm/°C for 1.3Q, and −250 ppm/°C
for 1.1Q. The Ga/In and P/As ratios of the Q-filmswere measured by secondary ion mass spectroscopy and correlated with full-wafer
maps of the PL wavelength and lattice mismatch to gain insight into the processes responsible for wafer nonuniformity in MOVPE. 相似文献
20.
H. Stanzl K. Wolf S. Bauer W. Kuhn A. Naumov W. Gebhardt 《Journal of Electronic Materials》1993,22(5):501-503
Metalorganic vapor phase epitaxy (MOVPE) growth experiments of ZnSe on GaAs (100) are described using ditertiary butylselenide
as the selenium source. The growth temperature was varied between 300 and 400°C and the growth rate was determined. Below
a vapor pressure ratio PSe/PZn of about 5, the selenium is the growth limiting component. The quality of the samples was analyzed by Nomarski microscopy,
x-ray diffraction, high resolution transmission electron microscopy, and photoluminescence. Although the selenium-precursor
was not specially purified, a sharp excitonic luminescence appears in samples grown at 400°C. The MOVPE growth of ZnSe still
suffers from prereactions when H2Se is used. The optimum growth is above 450°C even with precursors as DMSe or DESe which are less harmful than the hydride.
This paper reports results obtained with a novel selenium-precursor: ditertiarybutylselenide.1 相似文献