共查询到20条相似文献,搜索用时 15 毫秒
1.
We report the investigation of reversible-transient effects in photoluminescence (PL) of GaN layers in different measurement
ambients including air, oxygen, nitrogen, and hydrogen. While the presence of air and oxygen led to similar amounts of significant
decrease in overall luminescence, nitrogen and hydrogen produced a much smaller effect. Data on the different behaviors of
the near-band-edge and the deep-level (yellow luminescence (YL)) spectral components of the luminescence with change from
vacuum to the various ambient gases will be presented. A redshift of the deep-level luminescence band was noticed in oxygen
or air ambient that has been attributed to a decrease of the band bending. 相似文献
2.
Ming Luo B. L. Vanmil R. P. Tompkins Y. Cui T. Mounts U. N. Roy A. Burger T. H. Myers N. C. Giles 《Journal of Electronic Materials》2003,32(7):737-741
Incorporation of Cr into ZnTe epilayers grown by molecular-beam epitaxy (MBE) is reported. Photoluminescence (PL) using both
continuous wave (CW) and pulsed-excitation sources is used to characterize the radiative efficiency of doped layers in the
infrared region. The Cr2+ ions produce a broad emission band peaking in the 2–3 μm range, which is of potential use in tunable-laser devices. The optimum
Cr concentration for achieving bright, room-temperature infrared emission was found to be in the range from low- to mid-1018 cm−3. Temperature-dependent luminescence studies were performed to determine thermal-quenching activation energies. Using a pulsed-laser
operating at 1.9 μm, an investigation of emission lifetimes was made. The emission-decay curves for the Cr2+ recombination in ZnTe:Cr films could be described by a single exponential and were nearly independent of temperature from
80 K to 300 K. A room-temperature lifetime of ∼2.5 μsec in a ZnTe:Cr layer with [Cr] ∼1.4 × 1018 cm−3 compares favorably with values reported for bulk ZnTe:Cr. 相似文献
3.
Electrical properties of low-temperature GaAs grown by molecular beam epitaxy and migration enhanced epitaxy 总被引:1,自引:0,他引:1
Measurements on low-temperature GaAs epitaxial layers (LT-GaAs) grown by molecular beam epitaxy and migration enhanced epitaxy
showed that the excess arsenic incorporated during growth played a crucial role in determining their electrical properties.
The electrical transport in LT-GaAs grown by a standard molecular beam epitaxy proceeded mainly via a hopping process, which
showed a higher activation energy and onset temperature than those usually observed in lightly doped semiconductors. Using
migration enhanced epitaxy to grow LT-GaAs, we were able to substantially reduce the density of As-rich defects and to achieve
a good Hall mobility in Be-doped LT-GaAs. The study presented here indicates that, with controlled excess arsenic incorporation
during growth, LT-GaAs can vary in a range of conduction properties and thus can be engineered for different device applications. 相似文献
4.
D. B. Gladden W. D. Goodhue C. A. Wang G. A. Lincoln 《Journal of Electronic Materials》1992,21(1):109-114
Electrical and structural measurements have been performed on novel test structures incorporatingp-type GaAs epilayers grown by organometallic vapor phase atomic layer epitaxy on the vertical sidewalls of semi-insulating
GaAs rods formed by ion-beam-assisted etching. Preliminary results indicate that the vertical-sidewall epilayers have excellent
crystal quality and sufficient electrical quality to support a sidewall-epitaxy device technology. Some examples of candidate
electronic, electrooptic, and photonic devices for vertical-sidewall fabrication are FETs, resistors, waveguides, modulators,
and quantum-wire and quantum-dot lasers. 相似文献
5.
Conductive Be doped GaAs grown by molecular beam epitaxy at low substrate temperatures (300° C) was obtained for the first
time by using migration enhanced epitaxy (MEE) without subsequent annealing. The layers were characterized using Hall effect,
double crystal x-ray diffraction, and photoluminescence. With low arsenic exposure, the low temperature MEE layers doped with
Be had the same carrier density and similar luminescent efficiency as layers grown by conventional MBE at 580° C. Mobility
at 77 K was reduced somewhat for layers doped at 2 × 1017cm−3, which also exhibited hopping conductivity below 40 K. Double crystal x-ray diffraction showed that low temperature MEE samples
grown at low As exposure had the narrow linewidth associated with conventional MBE material grown at 580° C, unlike layers
grown by conventional MBE at low temperatures, which exhibit an expansion in lattice parameter. 相似文献
6.
T. Aoki Y. Chang G. Badano J. Zhao C. Grein S. Sivananthan David J. Smith 《Journal of Electronic Materials》2003,32(7):703-709
Surface-void defects observed in Hg1−xCdxTe (x ∼ 0.2–0.4) alloys grown by molecular-beam epitaxy (MBE) have been investigated using scanning and high-resolution transmission-electron
microscopy (HRTEM) as well as atomic force microscopy (AFM). These surface craters, which have been attributed to Hg-deficient
growth conditions, were found to originate primarily within the HgCdTe epilayer, rather than at the CdZnTe substrate, and
they were associated with the local development of polycrystalline morphology. High-resolution observations established the
occurrence of finely spaced HgCdTe/Te intergrowths with semicoherent and incoherent grain boundaries, as well as small HgCdTe
inclusions embedded within the Te grains. This study is the first time that high-resolution electron microscopy has been used
to investigate this type of defect. 相似文献
7.
M. Milanova T. Cholakova L. Bedikjan N. Stanev 《Journal of Electronic Materials》1994,23(11):1235-1237
Indium-doped GaAs layers are investigated by low-field Hall effect, photoluminescence, and double crystal x-ray diffraction
in order to study the influence of the In concentration on the electrical, optical, and crystallographic properties. The layers
were grown by liquid phase epitaxy from solution with In concentrations in the range 0–10 at.%. It was found that epitaxial
growth from the melt with 7 at.% In content produces the highest quality epitaxial layers. 相似文献
8.
We report on the realization of a modified delta doping technique to obtain doping profiles in MBE grown GaAs, measured by capacitance-voltage (C-V) methods with full-widths at half-maximum (FWHM)s of 25 ± 5Å and peak concentrations of up to 1.1 × 1019 cm?3. In this modified delta doping technique, both the Ga and Si shutters were opened for 15 sec during the delta doped layer growth while only the Si shutter is opened during conventional delta doping. Comparison of the two techniques under the same dopant flux and shutter-open-time interval shows that higher sheet-carrier concentrations with narrower FWHMs and higher peak concentrations are obtained with the modified delta doping than with the conventional delta doping method. This suggests that Si donor incorporation is enhanced by the Ga adatoms while broadening of the Si donor distribution is still negligible for this short time interval. The effects of the substrate temperature and the shutter-open time on the Si donor distribution have also been investigated. 相似文献
9.
本文研究了斜切割(100)Ge衬底上InxGa1-xAs/GaAs量子阱结构的分子束外延生长(In组分为0.17或者0.3)。所生长的样品用原子力显微镜、光致发光光谱和高分辨率透射电子显微镜进行了测量和表征。结果发现,为了生长没有反相畴的GaAs缓冲层,必须对Ge衬底进行高温退火。在GaAs外延层和InxGa1-xAs/GaAs量子阱结构的生长过程中,生长温度是一个至关重要的参数。文中讨论了温度对于外延材料质量的影响机理。通过优化生长温度,Ge衬底上的InxGa1-xAs/GaAs量子阱结构的光致发光谱具有很高的强度、很窄的线宽,样品的表面光滑平整。这些研究表面Ge 衬底上的III-V族化合物半导体材料有很大的器件应用前景。 相似文献
10.
Molecular beam epitaxy growth of an InxGa1-xAs/GaAs quantum well(QW) structure(x equals to 0.17 or 0.3) on offcut(100) Ge substrate has been investigated.The samples were characterized by atomic force microscopy,photoluminescence(PL),and high resolution transmission electron microscopy.High temperature annealing of the Ge substrate is necessary to grow GaAs buffer layer without anti-phase domains.During the subsequent growth of the GaAs buffer layer and an InxGa1-xAs/GaAs QW structure,temperature plays a key role. The mechanism by which temperature influences the material quality is discussed.High quality InxGa1-x As/GaAs QW structure samples on Ge substrate with high PL intensity,narrow PL linewidth and flat surface morphology have been achieved by optimizing growth temperatures.Our results show promising device applications forⅢ-Ⅴcompound semiconductor materials grown on Ge substrates. 相似文献
11.
Ming Y. Jow Bang Y. Maa Takashi Morishita P. Daniel Dapkus 《Journal of Electronic Materials》1995,24(1):25-29
We report the results of GaAs grown by vacuum atomic layer epitaxy using trimethylgallium (TMGa) and tertiarybutylarsine (TBAs)
as the group III and V sources. The growth rate saturates at one monolayer per cycle for a wide range of growth parameters.
The temperature window for monolayer growth is as wide as 70°C. All the films are p-type with the carrier concentration depending
on the exposure conditions of TMGa and TBAs. 相似文献
12.
13.
Gallium-arsenide p?n junction hyperabrupt varactor diodes have been grown by molecular-beam epitaxy. Near the junction the donor profile at depth x tracked x?1.2. A capacitance ratio C0/C12 of 10 is observed for bias voltages of 0 and 12 V. 相似文献
14.
Self-assembled GaAs nanowires were grown by molecular beam epitaxy (MBE) on un-pretreated Si(111) substrates under different As4/Ga flux ratios (V/III ratios). It has been found that the fraction of vertical wires would be nearly 100% when the As4/Ga ratio arrives 90. The transmission electron microscopy (TEM) and micro-photoluminescence (PL) spectra results have indicated that the GaAs nanowires grown under a larger V/III ratio (90) have a pure ZB structure. Field-effect transistors (FET) based on single nanowire were fabricated with GaAs nanowires grown under the larger V/III ratio (90). The characteristics of the FET reveal a hole concentration of 3.919×1017 cm−3 and a hole mobility of 0.417 cm2 V−1s−1. Photodetectors based on single nanowire and multiple nanowires structure with a metal-semiconductor-metal (MSM) electrode configuration have been proposed and demonstrated. All the photodetectors operating at room temperature exhibit good photoconductive performance, excellent stability, reproducibility and superior peak responsivity (87.67 A/W under 5 V for single nanowire photodetector). 相似文献
15.
M. S. Han T. W. Kang J. H. Leem B. K. Song Y. B. Hou W. H. Baek M. H. Lee J. H. Bahng K. J. Kim J. M. Kim H. K. Kim T. W. Kim 《Journal of Electronic Materials》1997,26(6):507-510
Spectroscopic ellipsometry and photoreflectance measurements on CdTe/GaAs strained heterostructures grown by moleculclr beam
epitaxy were carried out to investigate the effect of the strain and the dependence of the lattice parameter on the CdTe epitaxial
layer thicknesses. Compressive strains exist in CdTe layers thinner than 2 μm. As the strain increases, the value of the critical-point
energy shift increases linearly. These results indicate that the strains in the CdTe layers grown on GaAs substrates are strongly
dependent on the CdTe layer thickness.
Author to whom all correspondence should be addressed. 相似文献
16.
GaAs selective epitaxial growth by conventional molecular beam epitaxy (MBE) was studied while varying its growth conditions,
such as substrate temperature. As pressure, growth rate, and Si or Be doping. Selectivity is improved with the increase in
substrate temperature, and with the decrease in As pressure or growth rate. Si and Be were doped up to 3 x 1018 and 3 × 1019 cm−3, respectively. While no Si doping influence was observed, Be doping degraded the surface morphology. Selective epitaxial
growth by conventional MBE with appropriate growth conditions will be applicable to device fabrication. 相似文献
17.
The growth of InN on {0001} ZnO substrates by radio-frequency, plasma-assisted, molecular-beam epitaxy (RF-MBE) has been experimentally
investigated. The reflection high-energy electron diffraction (RHEED) pattern quickly recovered to a 1×1 streak pattern as
the InN growth was started on nitridated ZnO substrates, whereas the RHEED pattern of the ZnO substrate was spotty because
of plasma damage induced by nitridation. The full width at half maximum (FWHM) of the (0002) InN rocking curve was estimated
to be around 150 arcsec from x-ray diffraction (XRD). Furthermore, we observed a remarkable feature from our experiments;
namely, the crystal quality of InN does not seem to depend on the surface polarity of the ZnO substrate, while it is well
known that InN growth on GaN has strong polarity dependence. To investigate this tendency, we have also investigated the surface
stability of adatoms, In and N, on Zn- and O-face ZnO surfaces using a first-principles technique. From the theoretical study,
N adsorption is more stable on ZnO surfaces of both polarities compared with In adsorption. Accordingly, the preferential
initiation by N adatoms onto both ZnO surfaces can explain the unique style of InN growth on ZnO substrates. 相似文献
18.
M. Milanova A. Mintairov V. Rumyantsev K. Smekalin 《Journal of Electronic Materials》1999,28(1):35-38
This paper describes the spectral characteristics of GaAs solar cells grown by low-temperature liquid phase epitaxy (LPE). It demonstrates improvements in blue response and peak internal quantum efficiencies of 100 percent for an optimized cell structure with isovalent In doped base and ultrathin (<100Å) heavily doped cap p+-GaAs layer on the photosensitive surface. The conversion efficiency obtained from the optimized cells under one-sun AM 1.5 conditions is 23.4 percent. Our results indicate that the low-cost LPE-grown films are suitable for high-efficiency solar cells. 相似文献
19.
Void defects that occur under Hg deficient conditions during the metalorganic molecular beam epitaxy (MOMBE) growth of HgCdTe
have been characterized using secondary electron microscopy (SEM) and energy dispersion spectrometry (EDS) mapping as well
as by EDS quantitative analysis. For a set of HgCdTe samples grown under a range of Hg fluxes, it was found that the surface
morphology had a significant dependence on the Hg flux. An optimum growth window defined by a narrow range of Hg fluxes was
identified in which there exists a smooth surface with few voids, whereas at either side of the Hg window surfaces were rough.
This surface morphology correlated very well with a minimum in the x-ray line widths and maximum hole concentration and mobility
values. This correlation is important for the growth of HgCdTe materials and subsequent device fabrication. Several types
of void morphologies have been observed with different correlation to Te and Hg. It was found that there is a pronounced Te
enrichment and Hg deficiency associated with most of the developed voids, as compared to the composition of the HgCdTe films.
It was also found that most of the voids originated within the HgCdTe film. A mechanism for void formation and growth is proposed.
In addition, it was found that annealing caused the voids to separate from the HgCdTe film. 相似文献
20.
We examined the electrical and optical properties of vanadium-doped GaAs grown by metalorganic vapour phase epitaxy using vanadium tetrachloride (VCl4) as a novel dopant source. Samples with various vanadium incorporations were investigated. All samples were n type. The electron concentration dependence on the VCl4 flow rate was established. At 15 K, by comparison with undoped layers grown in the same conditions, photoluminescence spectra of V-doped exhibited three new emission bands: at 1.41, 1 and 0.72 eV. The 1 and 0.72 eV band emissions were attributed to V2+ and V3+ intracenter emission, while the 1.41 eV band was suggested to be a donor-bound transition. The identity of the donor is tentatively attributed to a donor complex that associates vanadium to an arsenic vacancy. From Hall effect as function of temperature, the donor ionisation energy was estimated to be about 102±5 meV. 相似文献