共查询到20条相似文献,搜索用时 390 毫秒
1.
M. S. Han S. R. Hahn H. C. Kwon Y. Bin T. W. Kang J. H. Leem Y. B. Hou H. C. Jeon J. K. Hyun Y. T. Jeoung H. K. Kim J. M. Kim T. W. Kim 《Journal of Electronic Materials》1998,27(6):680-683
Double-crystal x-ray rocking curve (DCRC) and secondary-ion mass-spectroscopy (SIMS) measurements have been performed to investigate the effect of rapid thermal annealing on the interdiffusion behavior of Hg in HgTe/CdTe superlattices grown on Cd0.96Zn0.04Te (211)B substrates by molecular beam epitaxy. The sharp satellite peaks of the DCRC measurements on a 100-period HgTe/CdTe (100Å/100Å) superlattice show a periodic arrangement of the superlattice with high-quality interfaces. The negative direction of the entropy change obtained from the diffusion coefficients as a function of the reciprocal of the temperature after RTA indicates that the Hg diffusion for the annealed HgTe/CdTe superlattice is caused by an interstitial mechanism. The Cd and the Hg concentration profiles near the annealed HgTe/CdTe superlattice interfaces, as measured by SIMS, show a nonlinear behavior for Hg, originating from the interstitial diffusion mechanism of the Hg composition. These results indicate that a nonlinear interdiffusion behavior is dominant for HgTe/CdTe superlattices annealed at 190°C and that the rectangular shape of HgTe/CdTe superlattices may change to a parabolic shape because of the intermixing of Hg and Cd due to the thermal treatment. 相似文献
2.
报道了用MBE的方法,在3英寸Si衬底上制备ZnTe/CdTe(211)B复合衬底材料的初步研究结果,该研究结果将能够直接应用于大面积Si基HgCdTe IRFPA材料的生长.经过Si(211)衬底低温表面处理、ZnTe低温成核、高温退火、高温ZnTe、CdTe层的生长研究,用MBE方法成功地获得了3英寸Si基ZnTe/CdTe(211)B复合衬底材料.CdTe厚度大于10μm,XRD FWHM平均值为120arc sec,最好达到100arc sec,无(133)孪晶和其他多晶晶向. 相似文献
3.
HgTe/CdTe superlattices (SL) have been studied for applications involving the detection of very-long wavelength infrared (VLWIR)
detectors. In this study, p-type HgTe/CdTe SLs were grown by molecular beam epitaxy (MBE). As-grown arsenic δ-doped HgTe/CdTe
SLs and undoped HgTe/CdTe SLs were characterized before and after annealing under different conditions using XRD, temperature-dependent
Hall-effect measurements, SIMS, and TEM. Incorporated arsenic atoms in a HgTe/CdTe SL were electrically activated without
the typical thermal annealing of alloy HgCdTe materials. 相似文献
4.
The surface growth kinetics of CdTe and HgTe have been investigated during molecular and metalorganic molecular beam epitaxy.
The surface growth kinetics was studied through in-situ measurements of the growth rate as a function of flux ratio and substrate
temperature on the (001), (111)B, and (211)B CdTe surface orientations. For the (001) and (111)B CdTe growth kinetics, the
existence of low binding energy surface precursor sites was proposed for both molecular and atomic growth species before lattice
incorporation. Intensity oscillations were observed during HgTe growth on misoriented (111)B surfaces and during CdTe growth
on the (211)B orientation. The (211)B surface reconstructions displayed both vicinal and singular surface characteristics,
depending on the growth flux ratio. 相似文献
5.
J. W. Park Jaesun Lee Y. M. Moon J. B. Choi M. S. Hahn B. K. Song Y. B. Hou T. W. Kang Kyung-Hwa Yoo C. A. Hoffman J. R. Meyer Y. T. Jeoung H. K. Kim J. M. Kim 《Journal of Electronic Materials》1997,26(6):584-587
We report transport results for molecular beam epitaxially grown HgTe/CdTe superlattices (SLs) with CdTe barrier thickness of Lb systematically varied from 100Å down to 20Å, and demonstrate the increasing intersubband mixing between adjacent layers with decreasing Lb. Magnetotransport data measured at 1.5K and for B up to 10T show monotonously varying features with Lb, implying a dimensional change from 2D to quasi-3D. As Lb decreases, the quantum Hall plateaus become weaker and the number of effective 2D channels are decreased, which indicates increasing growth-direction energy dispersion. This enhanced interlayer subband coupling with decreasing Lb is further confirmed by the angle-dependence of SdH oscillations. For Lb = 20Å, all of 2D-related transport behavior are washed out. A quantitative analysis with calculated subband energy dispersion relations demonstrates the close interplay between superlattice barrier thickness and the strength of the intersubband mixing. These transport results are directly related to successful control of the growth-axis carrier effective mass and will contribute to the development of high-performance HgTe/CdTe SL-based IR photo-voltaic devices and lasers, in which tunneling noise due to diffusion currents can be considerably reduced. 相似文献
6.
We have achieved metalorganic vapor-phase epitaxial growth of (211)B CdTe on Si without the requirement of a pregrowth high-temperature
oxide desorption step. This was achieved by growing a thin Ge film on the starting (211) Si substrates. To get (211)B CdTe
orientation, the Ge surface was exposed to As prior to the start of CdTe growth. A thin ZnTe interlayer between Ge and CdTe
has been shown to improve the CdTe surface morphology. 相似文献
7.
The type III band alignment of HgTe/CdTe superlattices leads to the interesting possibility of achieving very long wavelength
infrared (VLWIR) (15 μm and longer) cutoff wavelengths with either normal (HgTe layer thickness less than about 70 ? for CdTe
layer thickness of 50 ?) or inverted (HgTe thickness greater than about 70 ?) band structures. The inverted band structure
superlattices promise even greater cutoff wavelength control than the normal band structure ones. However, the electronic
band gaps of inverted band structure superlattices are substantially less than their optical band gaps, leading to large thermal
carrier concentrations even at temperature as low as 40 K. These high carrier concentrations in turn give rise to more rapid
Auger recombination than normal band structure superlattices with the same cutoff wavelengths. We conclude that the highest
performance is expected from VLWIR HgTe/CdTe superlattice-based detectors with normal band structure absorber layers. 相似文献
8.
R. W. Vanka K. A. Harris L. M. Mohnkern A. R. Reisinger T. H. Myers N. Otsuka 《Journal of Electronic Materials》1993,22(8):1107-1112
Two material properties important to the application of HgTe/CdTe superlattices for device fabrication are band gap uniformity
and thermal stability. In this paper, we present the results of an infrared photoluminescence study of (211)B HgTe/CdTe superlattices
grown by photon-assisted molecular beam epitaxy which show that cut-off wavelength uniformity can be controlled to a level
commensurate with the demands of advanced infrared detector fabrication. Infrared photoluminescence and transmission electron
microscopy were also employed to demonstrate that (211)B HgTe/CdTe superlattices are less prone to interdiffusion than previously
believed. 相似文献
9.
In this paper, we report on the atomic layer epitaxy (ALE) of CdTe on GaAs and Si by the organometallic vapor phase epitaxial
process at atmospheric pressure. Self-limiting growth at one monolayer was obtained over the temperature range from 250°C
to 320°C, under a wide range of reactant pressure conditions. A study of growth mechanism indicates that DMCd decomposes into
Cd on the surface and the Te precursors react catalytically on the Cd covered surface. We have used this ALE grown layer to
improve the crystal quality and the morphology of conventionally grown CdTe on GaAs. Improvement in the crystal quality was
also observed when ALE CdTe nucleation was carried out on Si pretreated with DETe at 420°C. Atomic layer epitaxy grown ZnTe
was used to obtain (100) oriented CdTe on (100) silicon. 相似文献
10.
Microstructural and optical characterization of CdTe(211)B/ZnTe/Si(211) grown by molecular beam epitaxy 总被引:2,自引:0,他引:2
S. Rujirawat David J. Smith J. P. Faurie G. Neu V. Nathan S. Sivananthan 《Journal of Electronic Materials》1998,27(9):1047-1052
CdTe layers have been grown by molecular beam epitaxy on 3 inch nominal Si(211) under various conditions to study the effect
of growth parameters on the structural quality. The microstructure of several samples was investigated by high resolution
transmission electron microscopy (HRTEM). The orientation of the CdTe layers was affected strongly by the ZnTe buffer deposition
temperature. Both single domain CdTe(133)B and CdTe(211)B were obtained by selective growth of ZnTe buffer layers at different
temperatures. We demonstrated that thin ZnTe buffer layers (<2 nm) are sufficient to maintain the (211) orientation. CdTe
deposited at ∼300°C grows with its normal lattice parameter from the onset of growth, demonstrating the effective strain accommodation
of the buffer layer. The low tilt angle (<1°) between CdTe[211] and Si[211] indicates that high miscut Si(211) substrates
are unnecessary. From low temperature photoluminescence, it is shown that Cd-substituted Li is the main residual impurity
in the CdTe layer. In addition, deep emission bands are attributed to the presence of AsTe and AgCd acceptors. There is no evidence that copper plays a role in the impurity contamination of the samples. 相似文献
11.
H. Luo L. R. Ram-Mohan G. L. Yang Y. Xuan J. K. Furdyna 《Journal of Electronic Materials》1993,22(8):1103-1106
We present a theoretical study of states quasi-localized in CdTe barriers of HgTe/CdTe superlattices. We show that the quasi-localization
of both electrons and holes will lead to strong Coulomb interaction, and thus to the formation of excitons. It is further
demonstrated that such quasi-localized states, including excitons, exhibit confinement effect similar to those of loclaized
states in quantum wells. 相似文献
12.
Y. Selamet Y. D. Zhou J. Zhao Y. Chang C. R. Becker R. Ashokan C. H. Grein S. Sivananthan 《Journal of Electronic Materials》2004,33(6):503-508
High-quality HgTe/CdTe superlattices (SLs) and device structures incorporating them were grown by molecular beam epitaxy (MBE)
on CdTe/Si substrates. In-situ techniques, such as reflection, high-energy electron diffraction and spectroscopic ellipsometry,
were extensively used to rigorously control the growth parameters. The full width at half maximum (FWHM) of x-ray double-crystal
rocking curves (DCRCs) were 100–150 arcsec, comparable to those of HgCdTe alloys grown on the same type of substrates. The
room-temperature Fourier transform infrared (FTIR) spectrum exhibits two-dimensional features characteristic of SLs. Trial
devices in a p+-n−-n+ format were fabricated by diffusing gold in order to further evaluate the HgTe/CdTe SL performance. Gold diffusion was chosen
to fabricate photovoltaic junctions in order to preserve the structural integrity of the SLs during the device processing.
Though no attempt was made in the current study to optimize the junction properties by Au diffusion, this method has proven
to be very useful for rapid preliminary evaluation. The measured spectral-response and detectivity data indicate the possibility
to fabricate photovoltaic devices on an HgTe/CdTe SL, although further work is needed to optimize the p-n junction fabrication. 相似文献
13.
14.
R. Sizmann P. Helgesen T. Colin T. Skauli S. Løvold 《Journal of Electronic Materials》1996,25(3):497-500
The use of a magnetic field for interband absorption experiments in the midinfrared regime can reveal the electronic band
structure of HgTe/CdTe superlattices. In high-quality samples pronounced magnetic field-induced absorption peaks are observed
in the transmission spectra due to hole to electron Landau level transitions. By extrapolating the excitation energies for
such transitions to B = 0, gap energies between several hole and electron subbands can be determined accurately. In addition,
we show that interband magnetoabsorption provides a sensitive feedback for growth of quantum structures. 相似文献
15.
M. Jaime-Vasquez R.N. Jacobs C. Nozaki J.D. Benson L.A. Almeida J. Arias J. Pellegrino 《Journal of Electronic Materials》2012,41(10):2975-2980
We present the results of a detailed study of the changes that occur on CdTe buffer layer surfaces grown on ZnTe/Si(211) and GaAs(211)B during the routine thermal cyclic annealing (TCA) process. Observations indicate that CdTe buffer layer surfaces are Te saturated when the TCA is performed under Te overpressure. In the absence of Te flux during the TCA step, the CdTe surface loses CdTe congruently and the typical CdTe nanowires show the presence of nodules on their surfaces. The observed changes in reflection high-energy electron diffraction patterns during TCA are explained in terms of surface chemistry and topography observations. Overall, the Te overpressure is necessary to maintain a smoother and pristine surface to continue the molecular beam epitaxy (MBE) growth. 相似文献
16.
W. Faschinger F. Hauzenberger P. Juza A. Pesek H. Sitter 《Journal of Electronic Materials》1993,22(5):497-500
CdTe-ZnTe superlattices (SLs) with a period ranging from 13 to 38Å have been grown by atomic layer epitaxy (ALE) on (001) GaAs-substrates. In a substrate temperature range between 270 and 290°C, the growth rate for both CdTe and ZnTe regulated itself to exactly 0.5 monolayers per reaction cycle, allowing the growth of very precisely tailored structures. For lower substrate temperatures, the growth rate raised to approximately 0.8 monolayers per cycle, but did not reach one monolayer per cycle before ZnTe started to grow polycrystalline. Using the ALE growth parameters for CdTe, SLs of CdTe and metastable cubic MnTe were prepared. The superlattices were characterized by high resolution x-ray diffraction and photoluminescence. A comparision of x-ray data and computer simulations, based on the dynamical theory of x-ray diffraction, show that the SLs exhibit excellent period constancy and very abrupt interfaces. 相似文献
17.
P. Moravec V.G. Ivanits’ka J. Franc Z.F. Tomashik V.M. Tomashik K. Mašek P.I. Feychuk L.P. Shcherbak P. Höschl R. Grill J. Walter 《Journal of Electronic Materials》2009,38(8):1645-1651
An iodine-based etching system, H2O2-HI-tartaric acid, was tested on CdTe samples with (110), (100), (111)A, and (111)B orientations. The etching rate of CdTe
was shown to depend on the sample orientation, ratio of etchant composition components, temperature, and rotation speed of
the disc. A study of the chemical composition and structure of the (211)B Cd1−x
Zn
x
Te surfaces etched under different conditions was carried out. X-ray photoelectron spectroscopy (XPS) measurements showed
that a nearly stoichiometric surface was achieved after heating of the etched surface in vacuum. Reflection high-energy electron
diffraction (RHEED) measurements revealed a very good single-crystalline surface layer in samples etched with HI-based solutions
as compared with bromine-methanol treatment. 相似文献
18.
The adsorption of CdTe layers on clean and As-passivated Si(211) substrates has been simulated by first-principle calculations
in this study. Based on the simulation results, we theoretically show the important roles of the As4 passivation during the epitaxial growth. Arsenic can saturate part of the dangling bonds and weaken the surface states. The
partial passivation finally induces the B-face polarity selection automatically. This conclusion can provide further explanations
for the successful growth of large area high-quality CdTe(211)B layers on the Si(211) substrates. 相似文献
19.
N. Lovergine P. Prete A. Cola M. Mazzer D. Cannoletta A. M. Mancini 《Journal of Electronic Materials》1999,28(6):695-699
The growth of thick CdTe epitaxial layers by the hydrogen transport vapor phase epitaxy (H2T-VPE) method is reported for the first time. The thermodynamics of the H2 transport method of CdTe is analyzed to determine the equilibrium partial pressures of the molecular species in the vapor
and its supersaturation as a function of growth conditions. (100)-oriented CdTe epilayers are successfully grown by H2T-VPE on hybrid ZnTe/GaAs(100) substrates prepared by metalorganic vapor phase epitaxy. Growth rates up to 10 μm/h are obtained
at temperatures ∼760°C and with the CdTe source temperature at 827°C. The achievement of even higher growth rates can be foreseen
by using the present method under slightly different conditions; several hundreds micron thick CdTe layers can be thus grown
by the H2T-VPE. CdTe samples have mirror-like, nearly featureless surfaces. Also, CdTe epilayers have shown a medium-to-high resistivity
at room temperature, possibly as a result of compensation by donor impurities diffusing from GaAs. Still the growth of highly
resistive layers by in-situ chlorine doping during the H2T-VPE growth is possible. In summary, H2T-VPE is a potential alternative to traditional melt- and vapor-growth methods for the synthesis of detector-grade CdTe for
application to the 1–100 keV x-ray energy range. 相似文献
20.
V. G. Ivanits’ka P. Moravec J. Franc Z. F. Tomashik P. I. Feychuk V. M. Tomashik L. P. Shcherbak K. Mašek P. Höschl 《Journal of Electronic Materials》2007,36(8):1021-1024
An iodine-based etching system, H2O2-HI-citric acid, has been developed and tested on CdTe samples with orientations (111)A, (111)B, (110), and (100). The etching
velocity of CdTe was shown to depend on sample orientation and other etching conditions. The surface roughness was comparable
with that of the surfaces after Br-methanol treatment. A comparative study of the chemical composition of the (211)B CdZnTe
surfaces etched under different conditions was performed. X-ray photoelectron spectroscopy (XPS) measurements showed that
all treated surfaces of CdZnTe samples are enriched with Te. The HI-based treatment seems to be more acceptable than the Br-methanol
treatment in terms of elimination of Te oxides from the surface, however. 相似文献