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1.
S. R. Rao S. S. Shintri J. K. Markunas R. N. Jacobs I. B. Bhat 《Journal of Electronic Materials》2010,39(7):996-1000
High-quality (211)B CdTe buffer layers on Si substrates are required to enable Hg1–x
Cd
x
Te growth and device fabrication on lattice-mismatched Si substrates. Metalorganic vapor-phase epitaxy (MOVPE) of (211)B CdTe
on Si substrates using Ge and ZnTe interlayers has been achieved. Cyclic annealing has been used during growth of thick CdTe
layers in order to improve crystal quality. The best (211)B CdTe/Si films grown in this study display a low x-ray diffraction
(XRD) rocking-curve full-width at half-maximum (FWHM) of 85 arcsec and etch pit density (EPD) of 2 × 106 cm−2. These values are the best reported for MOVPE-grown (211) CdTe/Si and are comparable to those for state-of-the-art molecular
beam epitaxy (MBE)-grown CdTe/Si. 相似文献
2.
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
3.
J.G.A. Wehner R.H. Sewell C.A. Musca J.M. Dell L. Faraone 《Journal of Electronic Materials》2007,36(8):877-883
Investigation into resonant-cavity-enhanced (RCE) HgCdTe detectors has revealed a discrepancy in the refractive index of the
CdTe layers grown by molecular beam epitaxy (MBE) for the detectors, compared with the reported value for crystalline CdTe.
The refractive index of the CdTe grown for RCE detectors was measured using ellipsometry and matches that of CdTe with an
inclusion of approximately 10% voids. X-ray measurements confirm that the sample is crystalline and strained to match the
lattice spacing of the underlying Hg(1−x)Cd(x)Te, while electron diffraction patterns observed during growth indicate that the CdTe layers exhibit some three-dimensional
structure. Secondary ion mass spectroscopy results further indicate that there is enhanced interdiffusion at the interface
between Hg(1−x)Cd(x)Te and CdTe when the Hg(1−x)Cd(x)Te is grown on CdTe, suggesting that the defects are nucleated within the CdTe layers. 相似文献
4.
As part of a systematic investigation of the effects of substrate surfaces on epitaxial growth, the transient behavior of
Hg1−xCdxTe film growth on (111)B CdTe by chemical vapor transport (CVT) has been studied as a function of growth time under vertical
stabilizing (hot end on top) and vertical destabilizing (hot end at bottom) ampoule orientations. The experim ental results
show the morphological transition of the Hg1−xCdxTe deposition on (111)B CdTe at 545°C from three-dimensional islands to layers within about 0.5 and 0.75 h for the growth
under vertical stabilizing and destabilizing conditions, respectively. The combined effects of small convective flow disturbances
on the growth morphology and defect formation are measurable. The overall trends of the time dependent growth rates and compositions
of the Hg1−xCdxTe epitaxial layers under stabilizing and destabilizing conditions are similar. The system atically higher growth rates of
the Hg1−xCdxTe films by about 10% under vertical destabilizing conditions could be influenced by a small convective contribution to the
mass transport. The combined results show that improved Hg1−xCdxTe epitaxial layers of low twin density on (111)B CdTe substrates can be obtained by CVT under vertical stabilizing conditions. 相似文献
5.
A. J. Stoltz M. Jaime-Vasquez J. D. Benson J. B. Varesi M. Martinka 《Journal of Electronic Materials》2006,35(6):1461-1464
High-density argon-hydrogen plasmas have been demonstrated to be very effective as etchants of CdTe, CdZnTe, and HgCdTe materials
for focal plane array applications. Understanding the physical, chemical, and electrical characteristics of these surfaces
is critical in elucidating the mechanisms of processing Hg1−xCdxTe. The ways in which these plasmas interact with HgCdTe, such as etch rates and loading, have been studied.1–11 However, little is known on how these plasmas affect the first few atomic layers of HgCdTe. In this study, the effects of
high-density plasmas on the surface of HgCdTe were examined. The combination of argon and hydrogen plasma etch leaves a well-ordered,
near-stoichiometric surface determined by both x-ray photoelectron spectroscopy and reflection high-energy electron diffraction
(RHEED). Starting with Hg0.78Cd0.22Te, we were able to produce surfaces with x=0.4 and a RHEED pattern sharp enough to measure 2×1 reconstruction. 相似文献
6.
M. Carmody J. G. Pasko D. Edwall M. Daraselia L. A. Almeida J. Molstad J. H. Dinan J. K. Markunas Y. Chen G. Brill N. K. Dhar 《Journal of Electronic Materials》2004,33(6):531-537
In the past several years, we have made significant progress in the growth of CdTe buffer layers on Si wafers using molecular
beam epitaxy (MBE) as well as the growth of HgCdTe onto this substrate as an alternative to the growth of HgCdTe on bulk CdZnTe
wafers. These developments have focused primarily on mid-wavelength infrared (MWIR) HgCdTe and have led to successful demonstrations
of high-performance 1024×1024 focal plane arrays (FPAs) using Rockwell Scientific’s double-layer planar heterostructure (DLPH)
architecture. We are currently attempting to extend the HgCdTe-on-Si technology to the long wavelength infrared (LWIR) and
very long wavelength infrared (VLWIR) regimes. This is made difficult because the large lattice-parameter mismatch between
Si and CdTe/HgCdTe results in a high density of threading dislocations (typically, >5E6 cm−2), and these dislocations act as conductive pathways for tunneling currents that reduce the RoA and increase the dark current of the diodes. To assess the current state of the LWIR art, we fabricated a set of test diodes
from LWIR HgCdTe grown on Si. Silicon wafers with either CdTe or CdSeTe buffer layers were used. Test results at both 78 K
and 40 K are presented and discussed in terms of threading dislocation density. Diode characteristics are compared with LWIR
HgCdTe grown on bulk CdZnTe. 相似文献
7.
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
8.
Molecular-beam epitaxial growth of HgCdTe infrared focal-plane arrays on silicon substrates for midwave infrared applications 总被引:1,自引:0,他引:1
T. J. de Lyon R. D. Rajavel J. A. Vigil J. E. Jensen O. K. Wu C. A. Cockrum S. M. Johnson G. M. Venzor S. L. Bailey I. Kasai W. L. Ahlgren M. S. Smith 《Journal of Electronic Materials》1998,27(6):550-555
Molecular beam epitaxy has been employed to deposit HgCdTe infrared detector structures on Si(112) substrates with performance
at 125K that is equivalent to detectors grown on conventional CdZnTe substrates. The detector structures are grown on Si via
CdTe(112)B buffer layers, whose structural properties include x-ray rocking curve full width at half maximum of 63 arc-sec
and near-surface etch pit density of 3–5 × 105 cm−2 for 9 μm thick CdTe films. HgCdTe p+-on-n device structures were grown by molecular beam epitaxy (MBE) on both bulk CdZnTe and Si with 125K cutoff wavelengths
ranging from 3.5 to 5 μm. External quantum efficiencies of 70%, limited only by reflection loss at the uncoated Si-vacuum
interface, were achieved for detectors on Si. The current-voltage (I-V) characteristics of MBE-grown detectors on CdZnTe and
Si were found to be equivalent, with reverse breakdown voltages well in excess of 700 mV. The temperature dependences of the
I-V characteristics of MBE-grown diodes on CdZnTe and Si were found to be essentially identical and in agreement with a diffusion-limited
current model for temperatures down to 110K. The performance of MBE-grown diodes on Si is also equivalent to that of typical
liquid phase epitaxy-grown devices on CdZnTe with R0A products in the 106–107 Θ-cm2 range for 3.6 μm cutoff at 125K and R0A products in the 104–105 Θ-cm2 range for 4.7 μm cutoff at 125K. 相似文献
9.
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
10.
K. Maruyama H. Nishino T. Okamoto S. Murakami T. Saito Y. Nishijima M. Uchikoshi M. Nagashima H. Wada 《Journal of Electronic Materials》1996,25(8):1353-1357
(lll)B CdTe layers free of antiphase domains and twins were directly grown on (100) Si 4°-misoriented toward<011> substrates,
using a metalorganic tellurium (Te) adsorption and annealing technique. Direct growth of (lll)B CdTe on (100) Si has three
major problems: the etching of Si by Te, antiphase domains, and twinning. Te adsorption at low temperature avoids the etching
effect and annealing at a high temperature grows single domain CdTe layers. Te atoms on the Si surface are arranged in two
stable positions, depending on annealing temperatures. We evaluated the characteristics of (lll)B CdTe and (lll)B HgCdTe layers.
The full width at half maximum (FWHM) of the x-ray double crystal rocking curve (DCRC) showed 146 arc sec at the 8 |im thick
CdTe layers. In Hg1−xCdxJe (x = 0.22 to 0.24) layers, the FWHMs of the DCRCs were 127 arc sec for a 7 (im thick layer and 119 arc sec for a 17 (im
thick layer. The etch pit densities of the HgCdTe were 2.3 x 106 cm2 at 7 ^m and 1.5 x 106 cm-2 at 17 um. 相似文献
11.
J. K. Markunas R. N. Jacobs P. J. Smith J. Pellegrino 《Journal of Electronic Materials》2011,40(8):1809-1814
Reduction of threading dislocation density is critical for improving the performance of HgCdTe detectors on lattice-mismatched
alternative substrates such as Si. CdTe buffer layers grown by molecular beam epitaxy (MBE), with thicknesses on the order
of 8 μm to 12 μm, have helped reduce dislocation densities in HgCdTe layers. In this study, the reduction of threading dislocation densities
in CdTe buffer layers grown on locally thinned Si substrates was examined. A novel Si back-thinning technique was developed
that maintained an epiready front surface and achieved Si thicknesses as low as 1.9 μm. Threading dislocation densities, acquired by defect decoration techniques, were reduced by as much as 60% for CdTe buffer
layers grown on these thinned regions when compared with unthinned regions. However, this reduction is inconsistent with prior
notions that threading dislocation propagation is dominated by image forces. Instead, the thickness gradient of thinned Si
may play a larger role. 相似文献
12.
High-Performance LWIR MBE-Grown HgCdTe/Si Focal Plane Arrays 总被引:1,自引:0,他引:1
Richard Bornfreund Joe P. Rosbeck Yen N. Thai Edward P. Smith Daniel D. Lofgreen Mauro F. Vilela Aimee A. Buell Michael D. Newton Kenneth Kosai Scott M. Johnson Terry J. de Lyon John E. Jensen Meimei Z. Tidrow 《Journal of Electronic Materials》2007,36(8):1085-1091
We have been actively pursuing the development of long-wavelength infrared (LWIR) HgCdTe grown by molecular beam epitaxy (MBE)
on large-area silicon substrates. The current effort is focused on extending HgCdTe/Si technology to longer wavelengths and
lower temperatures. The use of Si versus bulk CdZnTe substrates is being pursued due to the inherent advantages of Si, which
include available wafer sizes (as large as 300 mm), lower cost (both for the substrates and number of die per wafer), compatibility
with semiconductor processing equipment, and the match of the coefficient of thermal expansion with silicon read-out integrated
circuit (ROIC). Raytheon has already demonstrated low-defect, high-quality MBE-grown HgCdTe/Si as large as 150 mm in diameter.
The focal plane arrays (FPAs) presented in this paper were grown on 100 mm diameter (211)Si substrates in a Riber Epineat
system. The basic device structure is an MBE-grown p-on-n heterojunction device. Growth begins with a CdTe/ZnTe buffer layer followed by the HgCdTe active device layers; the entire
growth process is performed in␣situ to maintain clean interfaces between the various layers. In this experiment the cutoff wavelengths were varied from 10.0 μm to 10.7 μm at 78 K. Detectors with >50% quantum efficiency and R
0
A ∼1000 Ohms cm2 were obtained, with 256 × 256, 30 μm focal plane arrays from these detectors demonstrating response operabilities >99%.
Work supported by the Missile Defense Agency (MDA) through CACI Technologies, Inc. subcontract no. 601-05-0088, NVESD technical
task order no. TTO-01, prime contract no. DAAB07-03-D-C214, (delivery order no. 0016) 相似文献
13.
M.F. Vilela K.R. Olsson K. Rybnicek J.W. Bangs K.A. Jones S.F. Harris K.D. Smith D.D. Lofgreen 《Journal of Electronic Materials》2014,43(8):3018-3024
There is a well-known direct negative correlation between dislocation density and optoelectronic device performance. Reduction in detector noise associated with dislocations is an important target for improvement of mercury cadmium telluride (Hg1?x Cd x Te)-based material in order to broaden its use in the very long-wavelength infrared (VLWIR) regime. The lattice mismatch and differences in physical properties between substrates and the epitaxial Hg1?x Cd x Te layers cause an increased threading dislocation density. As demonstrated in this work, the presence of arsenic impurities via p-type doping in molecular beam epitaxy (MBE)-grown epitaxial crystal structure increases the etch pit density (EPD) of Hg1?x Cd x Te grown on Si substrates but not on CdZnTe substrates. This EPD increase is not observed in indium n-type-doped Hg1?x Cd x Te grown on either Si or CdZnTe substrates. This trend is also seen in layers with different cadmium compositions. All of the EPD variations of the structures studied here are shown to be independent of the MBE machine used to grow the structure. The fundamentals of this higher EPD are not yet completely understood. 相似文献
14.
The epitaxial layers of Hg1−xCdxTe (0.17≦×≦0.3) were grown by liquid phase epitaxy on CdTe (111)A substrates using a conventional slider boat in the open
tube H2 flow system. The as-grown layers have hole concentrations in the 1017− 1018 cm−3 range and Hall mobilities in the 100−500 cm2/Vs range for the x=0.2 layers. The surfaces of the layers are mirror-like and EMPA data of the layers show sharp compositional
transition at the interface between the epitaxial layer and the substrate. The effects of annealing in Hg over-pressure on
the properties of the as-grown layers were also investigated in the temperature range of 250−400 °C. By annealing at the temperature
of 400 °C, a compositional change near the interface is observed. Contrary to this, without apparent compositional change,
well-behaved n-type layers are obtained by annealing in the 250−300 °C temperature range. Sequential growth of double heterostructure,
Hgl−xCdxTe/Hgl−yCdyTe on a CdTe (111)A substrate was also demonstrated. 相似文献
15.
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
16.
R. Sudharsanan Z. C. Feng S. Perkowitz A. Rohatgi K. T. Pollard A. Erbil 《Journal of Electronic Materials》1989,18(3):453-455
Single crystal Cd1−x
Mn
x
Te (x=0.10–0.30) films have been grown by metalorganic vapor deposition (MOCVD) on (111) GaAs substrates with and without CdTe
buffer layers, at substrate temperatures of 380° to 450° C. Infrared phonon spectra reveal that the films grown at 420° C
substrate temperature have reasonable Mn concentration (>10%) and are of good quality in agreement with Raman measurements.
Spectral analysis also gives values for Mn concentration that agrees with photoluminescence measurements, and determines film
thickness. 相似文献
17.
F. Aqariden P.D. Dreiske M.A. Kinch P.K. Liao T. Murphy H.F. Schaake T.A. Shafer H.D. Shih T.H. Teherani 《Journal of Electronic Materials》2007,36(8):900-904
Hg1−x
Cd
x
Te samples of x ~ 0.3 (in the midwave infrared, or MWIR, spectral band) were prepared by molecular beam epitaxy (MBE) for fabrication into
30-μm-pitch, 256 × 256, front-side-illuminated, high-density vertically-integrated photodiode (HDVIP) focal plane arrays (FPAs).
These MBE Hg1−x
Cd
x
Te samples were grown on CdZnTe(211) substrates prepared in this laboratory; they were ~10-μm thick and were doped with indium to ~5 × 1014 cm−3. Standard HDVIP process flow was employed for array fabrication. Excellent array performance data were obtained from these
MWIR arrays with MBE HgCdTe material. The noise-equivalent differential flux (NEΔΦ) operability of the best array is 99.76%,
comparable to the best array obtained from liquid-phase epitaxy (LPE) material prepared in this laboratory. 相似文献
18.
T. T. Lam C. D. Moore R. L. Forrest M. S. Goorsky S. M. Johnson D. B. Leonard T. A. Strand T. J. Delyon M. D. Gorwitz 《Journal of Electronic Materials》2000,29(6):804-808
Shear strain is present in Hg0.68Cd0.32Te epitaxial layers grown by molecular beam epitaxy on (211)-oriented Cd1−yZnyTe substrates. Differences in the substrate zinc composition led to lattice mismatch between the epitaxial layer and the substrate.
The shear strain induced by the mismatch was measured using reciprocal space maps in the symmetric (422) and asymmetric (511)
and (333) reflections. In addition, strain relaxation through the formation of misfit dislocations was confirmed using double
crystal x-ray topography. Both the shear strain and the misfit dislocation density increased with increasing mismatch between
the epitaxial layer and the substrate. Lattice-matched layers were free of misfit dislocations and exhibited triple axis diffraction
rocking curve widths of approximately 6 arcsec. The combination of a thick epitaxial layer, a low index substrate, and the
potential for lattice mismatch indicates that both shear strains and misfit dislocations must be considered in the structural
analysis of HgCdTe/CdZnTe heterostructures. 相似文献
19.
C. F. Wan D. F. Weirauch R. Korenstein E. G. Bylander C. A. Castro 《Journal of Electronic Materials》1986,15(3):151-157
Hg1-xCdxTe liquid phase epitaxial (LPE) layers were grown from well-stirred large (100 g) Te-rich Hg-Cd-Te solutions by the dipping
method. Supercooling below the liquidus temperature in Te-rich solutions was studied by differential thermal analysis (DTA)
and film growth results. Although supercooling of 20 to more than 100° C was routinely measured in small (2 g) sample melts,
supercooling in larger melts (>100 g) was erratic and smaller. Factors affecting the degree of supercooling were identified
and a Hg-reflux was found to be a major cause of erratic melt behavior. The LPE reactor was modified to correct the Hg-reflux
action and a visual technique was developed for in situ determination of the liquidus temperature. A limited amount of supercooling
was found in the melt after reactor modification but it was difficult to maintain for extended durations before spontaneous
nucleation occurred. Consequently, programmed cooling rather than isothermal LPE was employed to grow many of the films reported
here. Hg1−xCdxTe epitaxial layers ofx = 0.2 to 0.25 were grown on (111)B oriented CdTe substrates by cooling the melts only 1–2° C below the previously measured
crystallization temperature. The small amount of cooling minimized composition variation with film thickness. Excellent surface
morphology was obtained when slow cooling rates of 0.02–0.05° C/ min were used. Cooling rates greater than 0.2° C/min created
rough, pitted surface. Precise substrate orientation was important in reducing surface terracing. Composition and thickness
uniformities of the epitaxial films were excellent as a result of substrate rotation. Run-to-run reproducibility of film composition
was ±0.01 inx. Hall measurements showed carrier concentrations in the range 2–20 × 1014 cm−3 with photoconductive lifetimes of 0.5–3.0 dms forx = 0.20 to 0.25. 相似文献
20.
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