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1.
S. R. Rao S. S. Shintri J. K. Markunas R. N. Jacobs I. B. Bhat 《Journal of Electronic Materials》2011,40(8):1790-1794
High-quality (211)B CdTe buffer layers are required during Hg1−x
Cd
x
Te heteroepitaxy on Si substrates. In this study, direct metalorganic vapor-phase epitaxy (MOVPE) of (211)B CdTe on Si, as
well as CdTe on Si using intermediate Ge and ZnTe layers, has been achieved. Tertiary butyl arsine was used as a precursor
to enable As surfactant action during CdTe MOVPE on Si. The grown CdTe/Si films display a best x-ray diffraction rocking-curve
full-width at half-maximum of 64 arc-s and a best Everson etch pit density of 3 × 105 cm−2. These values are the best reported for MOVPE-grown (211)B CdTe/Si and match state-of-the-art material grown using molecular-beam
epitaxy. 相似文献
2.
We report on the first successful growth of the ternary-alloy CdSexTe1−x(211) on 3-in. Si(211) substrates using molecular-beam epitaxy (MBE). The growth of CdSeTe was performed using a compound
CdTe effusion source and an elemental Se effusion source. The alloy composition (x) of the CdSexTe1−x ternary compound was controlled through the Se:CdTe flux ratios. Our results indicated that the crystalline quality of CdSeTe
decreases as the alloy composition increases, which is possibly due to an alloy-disordering effect. A similar trend was observed
for the CdZnTe ternary-alloy system. However, the alloy-disordering effect in CdSeTe was found to be less severe than that
in CdZnTe. We have carried out the growth of CdSeTe on Si at different temperatures. An optimized growth window was established
for CdSeTe on Si(211) to achieve high-crystalline-quality CdSeTe/Si layers with 4% Se. The as-grown layers exhibited excellent
surface morphology, low surface-defect density (less than 500 cm−2), and low x-ray full width at half maximum (FWHM) values near 100 arcsec. Additionally, the CdSeTe/Si layer exhibited excellent
lateral uniformity and the best etched-pit density (EPD) value on a 4% CdSeTe, measured to be as low as 1.4 × 105 cm−2. 相似文献
3.
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
4.
Giacomo Badano Patrice Gergaud Ivan C. Robin Xavier Baudry Benoît Amstatt Fréderique Gemain 《Journal of Electronic Materials》2010,39(7):908-911
We have used x-ray diffraction to assess the thickness dependence of strain in molecular-beam epitaxial (MBE) CdTe(211)/Ge(211).
For 25-nm-thick layers, we find tensile stress of 100 MPa and in-plane strain of ~1.5 × 10−3. This stress relaxes during growth and becomes zero beyond 1 μm. We use the Dunn and Koch formula to estimate the threading dislocation density from the full-width at half-maximum of the
(224) rocking curve. We then estimate the annihilation radius of MBE-grown CdTe(211)B/Ge(211) to be ~10 nm. Our layers have
etch pit densities between 5 × 107 cm−2 and 5 × 106 cm−2 for a thickness of 10 μm. The lowest densities were obtained by periodic annealing epitaxy. We discuss mechanisms for the saturation of the dislocation
density. 相似文献
5.
W. F. ZHAO R. N. JACOBS M. JAIME-VASQUEZ L. O. BUBULAC DAVID J. SMITH 《Journal of Electronic Materials》2011,40(8):1733-1737
Transmission electron microscopy and small-probe microanalysis have been used to investigate the microstructure and compositional
profiles of CdTe(211)B/ZnTe/Si(211) heterostructures. Thin ZnTe buffer layers and subsequent thick CdTe layers were grown
on Si(211) substrates using molecular beam epitaxy. Many {111}-type stacking faults were found to be present throughout the
entire ZnTe layer, terminating near the point of initiation of CdTe growth. A rotation angle of about 3.5° was observed between
lattice planes of the Si substrate and the final CdTe epilayer. Local lattice parameter measurement and elemental profiles
indicated that some intermixing of Zn and Cd had taken place. The average widths of the ZnTe layer and the (Cd,Zn)Te transition
region were found to be roughly 6.5 nm and 3.5 nm, respectively. 相似文献
6.
M. Niraula K. Yasuda H. Ohnishi H. Takahashi K. Eguchi K. Noda Y. Agata 《Journal of Electronic Materials》2006,35(6):1257-1261
Direct growth of high-quality, thick CdTe (211) epilayers, with thickness up to 100 μm, on Si (211) substrates in a vertical
metalorganic vapor phase epitaxy system is reported. In order to obtain homo-orientation growth on Si substrates, pretreatment
of the substrates was carried out in a separate chamber by annealing them together with pieces of GaAs at 800–900°C in a hydrogen
environment. Grown epilayers had very good substrate adhesion. The full-width at half-maximum (FWHM) value of the x-ray double-crystal
rocking curve from the CdTe (422) reflection decreased rapidly with increasing layer thickness and remained between 140–200
arcsec for layers >18 μm. Photoluminescence measurement at 4.2 K showed high-intensity, bound excitonic emission and very
small defect-related deep emissions, indicating the high crystalline quality of the grown layers. Furthermore, a CdTe/n+-Si heterojunction diode was fabricated that exhibited clear rectifying behavior. 相似文献
7.
J. K. Markunas L. A. Almeida R. N. Jacobs J. Pellegrino S. B. Qadri N. Mahadik J. Sanghera 《Journal of Electronic Materials》2010,39(6):738-742
Large-area high-quality Hg1–x
Cd
x
Te sensing layers for infrared imaging in the 8 μm to 12 μm spectral region are typically grown on bulk Cd1–x
Zn
x
Te substrates. Alternatively, epitaxial CdTe grown on Si or Ge has been used as a buffer layer for high-quality epitaxial
HgCdTe growth. In this paper, x-ray topographs and rocking-curve full-width at half-maximum (FWHM) data will be presented
for recent high-quality bulk CdZnTe grown by the vertical gradient freeze (VGF) method, previous bulk CdZnTe grown by the
vertical Bridgman technique, epitaxial CdTe buffer layers on Si and Ge, and a HgCdTe layer epitaxially grown on bulk VGF CdZnTe. 相似文献
8.
Y. P. Chen G. Brill E. M. Campo T. Hierl J. C. M. Hwang N. K. Dhar 《Journal of Electronic Materials》2004,33(6):498-502
We report on the first successful growth of the quaternary alloy Cd1−yZnySexTe1−x(211) on 3-in. Si(211) substrates using molecular beam epitaxy (MBE). The growth of CdZnSeTe was performed using a compound
CdTe effusion source, a compound ZnTe source, and an elemental Se effusion source. The alloy compositions (x and y) of the
Cd1−yZnySexTe1−x quaternary compound were controlled through the Se/CdTe and ZnTe/CdTe flux ratios, respectively. Our results indicated that
the surface morphology of CdZnSeTe improves as the Zn concentration decreases, which fits well with our previous observation
that the surface morphology of CdZnTe/Si is poorer than that of CdSeTe/Si. Although the x-ray full-width at half-maximums
(FWHMs) of CdZnSeTe/Si with 4% of Zn + Se remain relatively constant regardless of the individual Zn and Se concentrations,
etched-pit density (EPD) measurements exhibit a higher dislocation count on CdZnSeTe/Si layers with about 2% Zn and Se incorporated.
The enhancement of threading dislocations in these alloys might be due to an alloy disorder effect between ZnSe and CdTe phases.
Our results indicate that the CdZnSeTe/Si quaternary material with low Zn or low Se concentration (less than 1.5%) while maintaining
4% total Zn + Se concentration can be used as lattice-matching composite substrates for long-wavelength infrared (LWIR) HgCdTe
as an alternative for CdZnTe/Si or CdSeTe/Si. 相似文献
9.
Heteroepitaxy of HgCdTe (211)B on Ge substrates by molecular beam epitaxy for infrared detectors 总被引:3,自引:0,他引:3
J. P. Zanatta P. Ferret G. Theret A. Million M. Wolny J. P. Chamonal G. Destefanis 《Journal of Electronic Materials》1998,27(6):542-545
Epitaxial growth of (211)B CdTe/HgCdTe has been achieved on two inch germanium (Ge) by molecular beam epitaxy (MBE). Germanium
was chosen as an alternative substrate to circumvent the weaknesses of CdZnTe wafers. The ease of surface preparation makes
Ge an attractive candidate among many other alternative substrates. Best MBE CdTe growth results were obtained on (211) Ge
surfaces which were exposed to arsenic and zinc fluxes prior to the MBE growth. This surface preparation enabled CdTe growth
with B-face crystallographic polarity necessary for the HgCdTe growth. This process was reproducible, and produced a smooth
and mirror-like surface morphology. The best value of the {422} x-ray double diffraction full width at half maximum measured
from the HgCdTe layer was 68 arc-s. We present the 486 point maps of FWHM statistical values obtained from CdTe/Ge and HgCdTe/CdTe/Ge.
High resolution microscopy electron transmission and secondary ion mass spectroscopy characterization results are also presented
in this paper. High-performance middle wavelength infrared HgCdTe 32-element photodiode linear arrays, using the standard
LETI/LIR planar n-on-p ion implanted technology, were fabricated on CdTe/Ge substrates. At 78K, photodiodes exhibited very
high R0A figure of merit higher than 106 Ωcm−2 for a cutoff wavelength of 4.8 μm. Excess low frequency noise was not observed below 150K. 相似文献
10.
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
11.
M. Carmody A. Yulius D. Edwall D. Lee E. Piquette R. Jacobs D. Benson A. Stoltz J. Markunas A. Almeida J. Arias 《Journal of Electronic Materials》2012,41(10):2719-2724
Alternate substrates for molecular beam epitaxy growth of HgCdTe including Si, Ge, and GaAs have been under development for more than a decade. MBE growth of HgCdTe on GaAs substrates was pioneered by Teledyne Imaging Sensors (TIS) in the 1980s. However, recent improvements in the layer crystal quality including improvements in both the CdTe buffer layer and the HgCdTe layer growth have resulted in GaAs emerging as a strong candidate for replacement of bulk CdZnTe substrates for certain infrared imaging applications. In this paper the current state of the art in CdTe and HgCdTe MBE growth on (211)B GaAs and (211) Si at TIS is reviewed. Recent improvements in the CdTe buffer layer quality (double crystal rocking curve full-width at half-maximum?≈?30?arcsec) with HgCdTe dislocation densities of ≤106?cm?2 are discussed and comparisons are made with historical HgCdTe on bulk CdZnTe and alternate substrate data at TIS. Material properties including the HgCdTe majority carrier mobility and dislocation density are presented as a function of the CdTe buffer layer quality. 相似文献
12.
Li He Xiangliang Fu Qingzhu Wei Weiqiang Wang Lu Chen Yan Wu Xiaoning Hu Jianrong Yang Qinyao Zhang Ruijun Ding Xiaoshuang Chen Wei Lu 《Journal of Electronic Materials》2008,37(9):1189-1199
Results of first-principles calculations and experiments focusing on molecular beam epitaxy (MBE) growth of HgCdTe on the
alternative substrates of GaAs and Si are described. The As passivation on (2 × 1) reconstructed (211) Si and its effects
on the surface polarity of ZnTe or CdTe were clarified by examining the bonding configurations of As. The quality of HgCdTe
grown on Si was confirmed to be similar to that grown on GaAs. Typical surface defects in HgCdTe and CdTe were classified.
Good results for uniformities of full width at half maximum (FWHM) values of x-ray rocking curves, surface defects, and x values of Hg1−x
Cd
x
Te were obtained by refining the demanding parameters and possible tradeoffs. The sticking coefficient of As4 for MBE HgCdTe was determined. The effects of Hg-assisted annealing for As activation were investigated experimentally and
theoretically by examining the difference of the formation energy of AsHg and AsTe. Results of focal-plane arrays (FPAs) fabricated with HgCdTe grown on Si and on GaAs are discussed. 相似文献
13.
A series of n-type, indium-doped Hg1−xCdxTe (x∼0.225) layers were grown on Cd0.96Zn0.04Te(311)B substrates by molecular beam epitaxy (MBE). The Cd0.96Zn0.04Te(311)B substrates (2 cm × 3 cm) were prepared in this laboratory by the horizontal Bridgman method using double-zone-refined
6N source materials. The Hg1−xCdxTe(311)B epitaxial films were examined by optical microscopy, defect etching, and Hall measurements. Preliminary results indicate
that the n-type Hg1−xCdxTe(311)B and Hg1−xCdxTe(211)B films (x ∼ 0.225) grown by MBE have comparable morphological, structural, and electrical quality, with the best 77
K Hall mobility being 112,000 cm2/V·sec at carrier concentration of 1.9×10+15 cm−3. 相似文献
14.
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
15.
X.J. Wang C. Fulk F.H. Zhao D.H. Li S. Mukherjee Y. Chang R. Sporken R. Klie Z. Shi C.H. Grein S. Sivananthan 《Journal of Electronic Materials》2008,37(9):1200-1204
Narrow-bandgap PbSnSe has received much attention as a promising alternative material for mid- and long-wavelength high performance
of infrared detection at relatively high operating temperatures owing to the weak composition dependence of its bandgap, which
can intrinsically result in better uniformity. Additionally, it possesses a high dielectric constant that is anticipated to
be much more tolerant to defects. In addition, its growth by molecular beam epitaxy (MBE) can be easily accomplished in comparison
with HgCdTe and many III–V quantum well and superlattice materials. However, overcoming the high lattice and thermal mismatches
between PbSnSe and CdTe/Si substrates and improving the crystalline quality of PbSnSe grown on CdTe/Si substrates are challenges
that require further study. Additionally, interdiffusion between CdTe and PbSnSe can take place and lead to nonuniform distributions
of elements in PbSnSe. Epitaxial crystal PbSnSe alloy films were grown by MBE and were investigated by scanning and high-resolution
transmission electron microscopy (STEM/HRTEM). Etch pit density (EPD) measurements were done to determine the density of threading
defects in the films. EPD measurements on PbSnSe surfaces gave values in the mid-106 cm−2 range. The dislocations exposed as etch pits were found to accumulate and form small-angle grain boundaries lined up along
the () direction, which is the intersection line between (100) and (211) growth planes. 相似文献
16.
Jae Jin Kim R. N. Jacobs L. A. Almeida M. Jaime-Vasquez C. Nozaki David J. Smith 《Journal of Electronic Materials》2013,42(11):3142-3147
A microstructural study of HgCdTe/CdTe/GaAs(211)B and CdTe/GaAs(211)B heterostructures grown using molecular beam epitaxy (MBE) was carried out using transmission electron microscopy and small-probe microanalysis. High-quality MBE-grown CdTe on GaAs(211)B substrates was demonstrated to be a viable composite substrate platform for HgCdTe growth. In addition, analysis of interfacial misfit dislocations and residual strain showed that the CdTe/GaAs interface was fully relaxed except in localized regions where GaAs surface polishing had caused small pits. In the case of HgCdTe/CdTe/GaAs(211)B, the use of thin HgTe buffer layers between HgCdTe and CdTe for improving the HgCdTe crystal quality was also investigated. 相似文献
17.
Reproducible improvements in the metalorganic vapor phase epitaxy (MOVPE) grown CdTe buffer quality have been demonstrated
in a horizontal rectangular duct silica reactor by the use of integratedin situ monitoring that includes laser reflectometry, pyrometry, and Epison concentration monitoring. Specular He-Ne laser reflectance
was used toin situ monitor the growth rates, layer thickness, and morphology for both ZnTe and CdTe. The substrate surface temperature was monitored
using a pyrometer which was sensitive to the 2–2.6 μm waveband and accurate to ±1°C. The group II and group VI precursor concentrations
entering the reactor cell were measured simultaneously using two Epison ultrasonic monitors and significant variations were
observed with time, in particular for DIPTe. The surface morphology and growth rates were studied as a function of VI/II ratio
for temperatures between 380 and 460°C. The background morphology was the smoothest for VI/IIratio in the vicinity of 1.5–1.75
and could be maintained using Epison monitors. Regularly shaped morphological defects were found to be associated with morphological
defects in the GaAs/Si substrate. The x-ray rocking curve widths for CuKα (531) reflections were in the range of 2.3–3.6 arc-min, with no clear trend with changing VI/II ratio. X-ray topography images
of CdTe buffer layers on GaAs/Si showed a mosaic structure that is similar to CdTe/sapphire substrates. The etch pit density
in Hg1-xCdxTe layers grown onto improved buffer layers was as low as 6 x 106 cm-2 for low temperature MOVPE growth using the interdiffused multilayer process. 相似文献
18.
A study on preparation of Cd0.96Zn0.04Te(211)B substrates for growth of Hg1−xCdxTe epitaxial layers by molecular beam epitaxy (MBE) was investigated. The objective was to investigate the impact of starting
substrate surface quality on surface defects such as voids and hillocks commonly observed on MBE Hg1−xCdxTe layers. The results of this study indicate that, when the Cd0.96Zn0.04Te(211)B substrates are properly prepared, surface defects on the resulting MBE Hg1−xCdxTe films are reduced to minimum (size, ∼0.1 m and density ∼500/cm2) so that these MBE Hg1−xCdx Te films have surface quality as good as that of liquid phase epitaxial (LPE) Hg1−xCdxTe films currently in production in this laboratory. 相似文献
19.
T. Lien Tran Fariba Hatami W. Ted Masselink Vas P. Kunets G.J. Salamo 《Journal of Electronic Materials》2008,37(12):1799-1805
We describe the epitaxial growth of InSb films on both Si (001) and GaAs (100) substrates using molecular-beam epitaxy and
discuss the structural and electrical properties of the resulting films. The complete 2 μm InSb films on GaAs (001) were grown
at temperatures between 340°C and 420°C and with an Sb/In flux ratio of approximately 5 and a growth rate of 0.2 nm/s. The
films were characterized in terms of background electron concentration, mobility, and x-ray rocking curve width. Our best
results were for a growth temperature of 350°C, resulting in room-temperature mobility of 41,000 cm2/V s. For the growth of InSb on Si, vicinal Si(001) substrates offcut by 4° toward (110) were used. We investigated growth
temperatures between 340°C and 430°C for growth on Si(001). In contrast to growth on GaAs, the best results were achieved
at the high end of the range of T
S = C, resulting in a mobility of 26,100 cm2/V s for a 2 μm film. We also studied the growth and properties of InSb:Mn films on GaAs with Mn content below 1%. Our results
showed the presence of ferromagnetic ordering in the samples, opening a new direction in the diluted magnetic semiconductors. 相似文献
20.
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