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1.
M. F. Vilela A. A. Buell M. D. Newton G. M. Venzor A. C. Childs J. M. Peterson J. J. Franklin R. E. Bornfreund W. A. Radford S. M. Johnson 《Journal of Electronic Materials》2005,34(6):898-904
Middle wave infrared (MWIR) HgCdTe p-on-n double-layer heterojunctions (DLHJs) for infrared detector applications have been
grown on 100-mm Si (112) substrates by molecular beam epitaxy (MBE) for large format 2,560×512 focal plane arrays (FPAs).
In order to meet the performance requirements needed for these FPAs, cutoff and doping uniformity across the 100-mm wafer
are crucial. Reflection high-energy electron diffraction (RHEED), secondary ion mass spectrometry (SIMS), Fourier transform
infrared spectrometry (FTIR), x-ray, and etch pit density (EPD) were monitored to assess the reproducibility, uniformity,
and quality of detector material grown. Material properties demonstrated include x-ray full width half maximum (FWHM) as low
as 64 arc-sec, typical etch pit densities in mid-106 cm−2, cutoff uniformity below 5% across the full wafer, and typical density of macrodefects <1000 cm−2. The detector quality was established by using test structure arrays (TSAs), which include miniarray diodes with the similar
pitch as the detector array for easy measurement of critical parameters such as diode I-V characteristics and detector quantum
efficiency. Typical I-V curves show excellent R0A products and strong reverse breakdown characteristics. Detector quantum efficiency was measured to be in the 60–70% range
without an antireflection coating. 相似文献
2.
S. M. Johnson A. A. Buell M. F. Vilela J. M. Peterson J. B. Varesi M. D. Newton G. M. Venzor R. E. Bornfreund W. A. Radford E. P. G. Smith J. P. Rosbeck T. J. De Lyon J. E. Jensen V. Nathan 《Journal of Electronic Materials》2004,33(6):526-530
The heteroepitaxial growth of HgCdTe on large-area Si substrates is an enabling technology leading to the production of low-cost,
large-format infrared focal plane arrays (FPAs). This approach will allow HgCdTe FPA technology to be scaled beyond the limitations
of bulk CdZnTe substrates. We have already achieved excellent mid-wavelength infrared (MWIR) and short wavelength infrared
(SWIR) detector and FPA results using HgCdTe grown on 4-in. Si substrates using molecular beam epitaxy (MBE), and this work
was focused on extending these results into the long wavelength infrared (LWIR) spectral regime. A series of nine p-on-n LWIR
HgCdTe double-layer heterojunction (DLHJ) detector structures were grown on 4-in. Si substrates. The HgCdTe composition uniformity
was very good over the entire 4-in. wafer with a typical maximum nonuniformity of 2.2% at the very edge of the wafer; run-to-run
composition reproducibility, realized with real-time feedback control using spectroscopic ellipsometry, was also very good.
Both secondary ion mass spectrometry (SIMS) and Hall-effect measurements showed well-behaved doping and majority carrier properties,
respectively. Preliminary detector results were promising for this initial work and good broad-band spectral response was
demonstrated; 61% quantum efficiency was measured, which is very good compared to a maximum allowed value of 70% for a non-antireflection-coated
Si surface. The R0A products for HgCdTe/Si detectors in the 9.6-μm and 12-μm cutoff range were at least one order of magnitude below typical
results for detectors fabricated on bulk CdZnTe substrates. This lower performance was attributed to an elevated dislocation
density, which is in the mid-106 cm−2 range. The dislocation density in HgCdTe/Si needs to be reduced to <106 cm−2 to make high-performance LWIR detectors, and multiple approaches are being tried across the infrared community to achieve
this result because the technological payoff is significant. 相似文献
3.
Status of LWIR HgCdTe-on-Silicon FPA Technology 总被引:1,自引:0,他引:1
M. Carmody J.G. Pasko D. Edwall E. Piquette M. Kangas S. Freeman J. Arias R. Jacobs W. Mason A. Stoltz Y. Chen N.K. Dhar 《Journal of Electronic Materials》2008,37(9):1184-1188
The use of silicon as an alternative substrate to bulk CdZnTe for epitaxial growth of HgCdTe for infrared detector applications
is attractive because of potential cost savings as a result of the large available sizes and the relatively low cost of silicon
substrates. However, the potential benefits of silicon as a substrate have been difficult to realize because of the technical
challenges of growing low-defect-density HgCdTe on silicon where the lattice mismatch is ∼19%. This is especially true for
long-wavelength infrared (LWIR) HgCdTe detectors where the performance can be limited by the high (∼5 × 106 cm−2) dislocation density typically found in HgCdTe grown on silicon. The current status of LWIR (9 μm to 11 μm at 78 K) HgCdTe on silicon focal-plane arrays (FPAs) is reviewed. Recent progress is covered including improvements in noise
equivalent differential temperature (NEDT) and array operability. NEDT of <25 mK and NEDT operability >99% are highlighted
for 640 × 480 pixel, 20-μm-pitch FPAs. 相似文献
4.
E. A. Patten P. M. Goetz M. F. Vilela K. Olsson D. D. Lofgreen J. G. Vodicka S. M. Johnson 《Journal of Electronic Materials》2010,39(10):2215-2219
HgCdTe grown on large-area Si substrates allows for larger array formats and potentially reduced focal-plane array (FPA) cost
compared with smaller, more expensive CdZnTe substrates. The goal of this work is to evaluate the use of HgCdTe/Si for mid-wavelength/long-wavelength
infrared (MWIR/LWIR) dual-band FPAs. A series of MWIR/LWIR dual-band HgCdTe triple-layer n-P-n heterojunction (TLHJ) device structures were grown by molecular-beam epitaxy (MBE) on 100-mm (211)Si substrates. The wafers
showed low macrodefect density (<300 cm−2) and was processed into 20-μm-unit-cell 640 × 480 detector arrays which were mated to dual-band readout integrated circuits (ROICs) to produce FPAs. The
measured 80-K cutoff wavelengths were 5.5 μm for MWIR and 9.4 μm for LWIR, respectively. The FPAs exhibited high pixel operabilities in each band, with noise equivalent differential temperature
(NEDT) operabilities of 99.98% for the MWIR band and 99.6% for the LWIR band demonstrated at 84 K. 相似文献
5.
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
6.
Molecular beam epitaxy grown long wavelength infrared HgCdTe on Si detector performance 总被引:1,自引:0,他引:1
M. Carmody J. G. Pasko D. Edwall R. Bailey J. Arias S. Cabelli J. Bajaj L. A. Almeida J. H. Dinan M. Groenert A. J. Stoltz Y. Chen G. Brill N. K. Dhar 《Journal of Electronic Materials》2005,34(6):832-838
The use of silicon as a substrate alternative to bulk CdZnTe for epitaxial growth of HgCdTe for infrared (IR) detector applications
is attractive because of potential cost savings as a result of the large available sizes and the relatively low cost of silicon
substrates. However, the potential benefits of silicon as a substrate have been difficult to realize because of the technical
challenges of growing low defect density HgCdTe on silicon where the lattice mismatch is ∼19%. This is especially true for
LWIR HgCdTe detectors where the performance can be limited by the high (∼5×106 cm−2) dislocation density typically found in HgCdTe grown on silicon. We have fabricated a series of long wavelength infrared
(LWIR) HgCdTe diodes and several LWIR focal plane arrays (FPAs) with HgCdTe grown on silicon substrates using MBE grown CdTe
and CdSeTe buffer layers. The detector arrays were fabricated using Rockwell Scientific’s planar diode architecture. The diode
and FPA and results at 78 K will be discussed in terms of the high dislocation density (∼5×106 cm2) typically measured when HgCdTe is grown on silicon substrates. 相似文献
7.
Role of Dislocation Scattering on the Electron Mobility of n-Type Long Wave Length Infrared HgCdTe on Silicon 总被引:1,自引:0,他引:1
M. Carmody D. Edwall J. Ellsworth J. Arias M. Groenert R. Jacobs L.A. Almeida J.H. Dinan Y. Chen G. Brill N.K. Dhar 《Journal of Electronic Materials》2007,36(8):1098-1105
It has been reported that the basic electrical properties of n-type long wave length infrared (LWIR) HgCdTe grown on silicon, including the majority carrier mobility (μ
e) and minority carrier lifetime (τ), are qualitatively comparable to those reported for LWIR HgCdTe grown on bulk CdZnTe by
molecular beam epitaxy (MBE). Detailed measurements of the majority carrier mobility have revealed important differences between
the values measured for HgCdTe grown on bulk CdZnTe and those measured for HgCdTe grown on buffered silicon substrates. The
mobility of LWIR HgCdTe grown on buffered silicon by MBE is reported over a large temperature range and is analyzed in terms
of standard electron scattering mechanisms. The role of dislocation scattering is addressed for high dislocation density HgCdTe
grown on lattice-mismatched silicon. Differences between the low temperature mobility data of HgCdTe grown on bulk CdZnTe
and HgCdTe grown on silicon are partially explained in terms of the dislocation scattering contribution to the total mobility. 相似文献
8.
E. P. G. Smith G. M. Venzor A. M. Gallagher M. Reddy J. M. Peterson D. D. Lofgreen J. E. Randolph 《Journal of Electronic Materials》2011,40(8):1630-1636
Raytheon Vision Systems (RVS) continues to further its capability to deliver state-of-the-art high-performance, large-format,
HgCdTe focal-plane arrays (FPAs) for dual-band long-wavelength infrared (L/LWIR) detection. Specific improvements have recently
been implemented at RVS in molecular-beam epitaxy (MBE) growth and wafer fabrication and are reported in this paper. The aim
of the improvements is to establish producible processes for 512 × 512 30-μm-unit-cell L/LWIR FPAs, which has resulted in: the growth of triple-layer heterojunction (TLHJ) HgCdTe back-to-back photodiode
detector designs on 6 cm × 6 cm CdZnTe substrates with 300-K Fourier-transform infrared (FTIR) cutoff wavelength uniformity
of ±0.1 μm across the entire wafer; demonstration of detector dark-current performance for the longer-wavelength detector band approaching
that of single-color liquid-phase epitaxy (LPE) LWIR detectors; and uniform, high-operability, 512 × 512 30-μm-unit-cell FPA performance in both LWIR bands. 相似文献
9.
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
10.
M. Reddy J. M. Peterson S. M. Johnson T. Vang J. A. Franklin E. A. Patten W. A. Radford J. W. Bangs D. D. Lofgreen 《Journal of Electronic Materials》2009,38(8):1764-1770
This paper presents the progress in the molecular beam epitaxy (MBE) growth of HgCdTe on large-area Si and CdZnTe substrates
at Raytheon Vision Systems. We report a very high-quality HgCdTe growth, for the first time, on an 8 cm × 8 cm CdZnTe substrate.
This paper also describes the excellent HgCdTe growth repeatability on multiple 7 cm × 7 cm CdZnTe substrates. In order to
study the percentage wafer area yield and its consistency from run to run, small lots of dual-band long-wave infrared/long-wave
infrared triple-layer heterojunction (TLHJ) layers on 5 cm × 5 cm CdZnTe substrates and single-color double-layer heterojunction
(DLHJ) layers on 6-inch Si substrates were grown and tested for cutoff wavelength uniformity and micro- and macrovoid defect
density and uniformity. The results show that the entire lot of 12 DLHJ-HgCdTe layers on 6-inch Si wafers meet the testing
criterion of cutoff wavelength within the range 4.76 ± 0.1 μm at 130 K and micro- and macrovoid defect density of ≤50 cm−2 and 5 cm−2, respectively. Likewise, five out of six dual-band TLHJ-HgCdTe layers on 5 cm × 5 cm CdZnTe substrates meet the testing criterion
of cutoff wavelength within the range 6.3 ± 0.1 μm at 300 K and micro- and macrovoid defect density of ≤2000 cm−2 and 500 cm−2, respectively, on the entire wafer area. Overall we have found that scaling our HgCdTe MBE process to a 10-inch MBE system
has provided significant benefits in terms of both wafer uniformity and quality. 相似文献
11.
G. Brill S. Farrell Y. P. Chen P. S. Wijewarnasuriya Mulpuri V. Rao J. D. Benson N. Dhar 《Journal of Electronic Materials》2010,39(7):967-973
Current growth methods of HgCdTe/Cd(Se)Te/Si by molecular-beam epitaxy (MBE) result in a dislocation density of mid 106 cm−2 to low 107 cm−2. Although the exact mechanism is unknown, it is well accepted that this high level of dislocation density leads to poorer
long-wavelength infrared (LWIR) focal-plane array (FPA) performance, especially in terms of operability. We have conducted
a detailed study of ex situ cycle annealing of HgCdTe/Cd(Se)Te/Si material in order to reduce the total number of dislocations present in as-grown material.
We have successfully and consistently shown a reduction of one half to one full order of magnitude in the number of dislocations
as counted by etch pit density (EPD) methods. Additionally, we have observed a corresponding decrease in x-ray full-width
at half-maximum (FWHM) of ex situ annealed HgCdTe/Si layers. Among all parameters studied, the total number of annealing cycles seems to have the greatest
impact on dislocation reduction. Currently, we have obtained numerous HgCdTe/Si layers which have EPD values measuring ~1 × 106 cm−2 after completion of thermal cycle annealing. Preliminary Hall measurements indicate that electrical characteristics of the
material can be maintained. 相似文献
12.
O. Gravrand L. Mollard C. Largeron N. Baier E. Deborniol Ph. Chorier 《Journal of Electronic Materials》2009,38(8):1733-1740
The very long infrared wavelength (>14 μm) is a very challenging range for the design of mercury cadmium telluride (HgCdTe) large focal plane arrays (FPAs). The need
(mainly expressed by the space industry) for very long wave FPAs appears very difficult to fulfil. High homogeneity, low defect
rate, high quantum efficiency, low dark current, and low excess noise are required. Indeed, for such wavelength, the corresponding
HgCdTe gap becomes smaller than 100 meV and each step from the metallurgy to the technology becomes critical. This paper aims
at presenting a status of long and very long wave FPAs developments at DEFIR (LETI-LIR/Sofradir joint venture). This study
will focus on results obtained in our laboratory for three different ion implanted technologies: n-on-p mercury vacancies doped technology, n-on-p extrinsic doped technology, and p-on-n arsenic on indium technology. Special focus is given to 15 μm cutoff n/p FPA fabricated in our laboratory demonstrating high uniformity, diffusion and shot noise limited photodiodes at 50 K. 相似文献
13.
G. Brill S. Velicu P. Boieriu Y. Chen N. K. Dhar T. S. Lee Y. Selamet S. Sivananthan 《Journal of Electronic Materials》2001,30(6):717-722
The traditional substrate of choice for HgCdTe material growth has been lattice matched bulk CdZnTe material. However, as
larger array sizes are required for future devices, it is evident that current size limitations of bulk substrates will become
an issue and therefore large area Si substrates will become a requirement for HgCdTe growth in order to maintain the cost-efficiency
of future systems. As a result, traditional substrate mounting methods that use chemical compounds to adhere the substrate
to the substrate holder may pose significant technical challenges to the growth and fabrication of HgCdTe on large area Si
substrates. For these reasons, non-contact (indium-free) substrate mounting was used to grow mid-wave infrared (MWIR) HgCdTe
material on 3″ CdTe/Si substrates. In order to maintain a constant tepilayer temperature during HgCdTe nucleation, reflection
high-energy electron diffraction (RHEED) was implemented to develop a substrate temperature ramping profile for HgCdTe nucleation.
The layers were characterized ex-situ using Fourier transform infrared (FTIR) and etch pit density measurements to determine
structural characteristics. Dislocation densities typically measured in the 9 106 cm−2 to 1 107 cm−2 range and showed a strong correlation between ramping profile and Cd composition, indicating the uniqueness of the ramping
profiles. Hall and photoconductive decay measurements were used to characterize the electrical properties of the layers. Additionally,
both single element and 32 32 photovoltaic devices were fabricated from these layers. A RA value of 1.8 106-cm2 measured at −40 mV was obtained for MWIR material, which is comparable to HgCdTe grown on bulk CdZnTe substrates. 相似文献
14.
Heteroepitaxy of HgCdTe(112) infrared detector structures on Si(112) substrates by molecular-beam epitaxy 总被引:4,自引:0,他引:4
T. J. De Lyon R. D. Rajavel J. E. Jensen O. K. Wu S. M. Johnson C. A. Cockrum G. M. Venzor 《Journal of Electronic Materials》1996,25(8):1341-1346
High-quality, single-crystal epitaxial films of CdTe(112)B and HgCdTe(112)B have been grown directly on Si(112) substrates
without the need for GaAs interfacial layers. The CdTe and HgCdTe films have been characterized with optical microscopy, x-ray
diffraction, wet chemical defect etching, and secondary ion mass spectrometry. HgCdTe/Si infrared detectors have also been
fabricated and tested. The CdTe(112)B films are highly specular, twin-free, and have x-ray rocking curves as narrow as 72
arc-sec and near-surface etch pit density (EPD) of 2 × 106 cm−2 for 8 μm thick films. HgCdTe(112)B films deposited on Si substrates have x-ray rocking curve FWHM as low as 76 arc-sec and
EPD of 3-22 × 106 cm−2. These MBE-grown epitaxial structures have been used to fabricate the first high-performance HgCdTe IR detectors grown directly
on Si without use of an intermediate GaAs buffer layer. HgCdTe/Si infrared detectors have been fabricated with 40% quantum
efficiency and R0A = 1.64 × 104 Ωm2 (0 FOV) for devices with 7.8 μm cutoff wavelength at 78Kto demonstrate the capability of MBE for growth of large-area HgCdTe
arrays on Si. 相似文献
15.
Ashok K. Sood James E. Egerton Yash R. Puri Enrico Bellotti Donald D’Orsogna Latika Becker Raymond Balcerak Ken Freyvogel Robert Richwine 《Journal of Electronic Materials》2005,34(6):909-912
Multicolor infrared (IR) focal planes are required for high-performance sensor applications. These sensors will require multicolor
focal plane arrays (FPAs) that will cover various wavelengths of interest in mid wavelength infrared/long wavelength infrared
(MWIR/LWIR) and long wavelength infrared/very long wavelength infrared (LWIR/VLWIR) bands. There has been significant progress
in HgCdTe detector technology for multicolor MWIR/LWIR and LWIR/VLWIR FPAs.1–3 Two-color IR FPAs eliminate the complexity of multiple single-color IR FPAs and provide a significant reduction of weight
and power in simpler, reliable, and affordable systems. The complexity of a multicolor IR detector MWIR/LWIR makes the device
optimization by trial and error not only impractical but also merely impossible. Too many different geometrical and physical
variables need to be considered at the same time. Additionally, material characteristics are only relatively controllable
and depend on the process repeatability. In this context, the ability of performing “simulation experiments” where only one
or a few parameters are carefully controlled is paramount for a quantum improvement of a new generation of multicolor detectors
for various applications. 相似文献
16.
K. D. Maranowski J. M. Peterson S. M. Johnson J. B. Varesi A. C. Childs R. E. Bornfreund A. A. Buell W. A. Radford T. J. de Lyon J. E. Jensen 《Journal of Electronic Materials》2001,30(6):619-622
HgCdTe p-on-n double layer heterojunctions (DLHJs) for mid-wave infrared (MWIR) detector applications have been grown on 100
mm (4 inch) diameter (211) silicon substrates by molecular beam epitaxy (MBE). The structural quality of these films is excellent,
as demonstrated by x-ray rocking curves with full widths at half maximum (FWHMs) of 80–100 arcsec, and etch pit densities
from 1 106 to 7 106 cm−2. Morphological defect densities for these layers are generally less than 1000 cm−2. Improving Hg flux coverage of the wafer during growth can reduce void defects near the edges of the wafers. Improved tellurium
source designs have resulted in better temporal flux stability and a reduction of the center to edge x-value variation from
9% to only 2%. Photovoltaic MWIR detectors have been fabricated from some of these 100mm wafers, and the devices show performance
at 140 K which is comparable to other MWIR detectors grown on bulk CdZnTe substrates by MBE and by liquid phase epitaxy. 相似文献
17.
M. Reddy J.M. Peterson D.D. Lofgreen J.A. Franklin T. Vang E.P.G. Smith J.G.A. Wehner I. Kasai J.W. Bangs S.M. Johnson 《Journal of Electronic Materials》2008,37(9):1274-1282
Molecular beam epitaxy (MBE) growth of HgCdTe on large-size Si (211) and CdZnTe (211)B substrates is critical to meet the
demands of extremely uniform and highly functional third-generation infrared (IR) focal-panel arrays (FPAs). We have described
here the importance of wafer maps of HgCdTe thickness, composition, and the macrodefects across the wafer not only to qualify
material properties against design specifications but also to diagnose and classify the MBE-growth-related issues on large-area
wafers. The paper presents HgCdTe growth with exceptionally uniform composition and thickness and record low macrodefect density
on large Si wafers up to 6-in in diameter for the detection of short-wave (SW), mid-wave (MW), and long-wave (LW) IR radiation.
We have also proposed a cost-effective approach to use the growth of HgCdTe on low-cost Si substrates to isolate the growth-
and substrate-related problems that one occasionally comes across with the CdZnTe substrates and tune the growth parameters
such as growth rate, cutoff wavelength (λ
cutoff) and doping parameters before proceeding with the growth on costly large-area CdZnTe substrates. In this way, we demonstrated
HgCdTe growth on large CdZnTe substrates of size 7 cm × 7 cm with excellent uniformity and low macrodefect density.
Received December 7, 2007; accepted February 25, 2008 相似文献
18.
M. Reddy J. M. Peterson D. D. Lofgreen T. Vang E. A. Patten W. A. Radford S. M. Johnson 《Journal of Electronic Materials》2010,39(7):974-980
This paper describes molecular-beam epitaxy growth of mid-wavelength infrared (MWIR) and long-wavelength infrared (LWIR) dual-band
device structures on large-area (6 cm × 6 cm) CdZnTe substrates. Wafer-level composition and defect mapping techniques were
used to investigate the limiting mechanisms in improving the cutoff wavelength (λ
c) uniformity and reducing the defect density. Structural quality of epitaxial layers was monitored using etch pit density
(EPD) measurements at various depths in the epitaxial layers. Finally, 640 × 480, 20-μm-pixel-pitch dual-band focal-plane arrays (FPAs) were fabricated to demonstrate the overall maturity of growth and fabrication
processes of epitaxial layers. The MWIR/LWIR dual-band layers, at optimized growth conditions, show a λ
c variation of ±0.15 μm across a 6 cm × 6 cm CdZnTe substrate, a uniform low macrodefect density with an average of 1000 cm−2, and an average EPD of 1.5 × 105 cm−2. FPAs fabricated using these layers show band 1 (MWIR) noise equivalent temperature difference (NETD) operability of 99.94%
and band 2 (LWIR) NETD operability of 99.2%, which are among the highest reported to date. 相似文献
19.
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
20.
A. J. Stoltz J. D. Benson M. Carmody S Farrell P. S. Wijewarnasuriya G. Brill R. Jacobs Y. Chen 《Journal of Electronic Materials》2011,40(8):1785-1789
HgCdTe, because of its narrow band gap and low dark current, is the infrared detector material of choice for several military
and commercial applications. CdZnTe is the substrate of choice for HgCdTe as it can be lattice matched, resulting in low-defect-density
epitaxy. Being often small and not circular, layers grown on CdZnTe are difficult to process in standard semiconductor equipment.
Furthermore, CdZnTe can often be very expensive. Alternative inexpensive large circular substrates, such as silicon or gallium
arsenide, are needed to scale production of HgCdTe detectors. Growth of HgCdTe on these alternative substrates has its own
difficulty, namely a large lattice mismatch (19% for Si and 14% for GaAs). This large mismatch results in high defect density
and reduced detector performance. In this paper we discuss ways to reduce the effects of dislocations by gettering these defects
to the edge of a reticulated structure. These reticulated surfaces enable stress-free regions for dislocations to glide to.
In the work described herein, HgCdTe-on-Si diodes have been produced with R
0
A
0 of over 400 Ω cm2 at 78 K and cutoff of 10.1 μm. Further, these diodes have good uniformity at 78 K at both 9.3 μm and 10.14 μm. 相似文献