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1.
K. Moazzami D. Liao J. D. Phillips D. L. Lee M. Carmody M. Zandian D. D. Edwall 《Journal of Electronic Materials》2003,32(7):646-650
Hg1−xCdxTe is an important material for high-performance infrared detection for a wide spectral range, from 1.7 μm to beyond 14 μm.
An accurate understanding of the relationship between optical absorption and bandgap energy of this semiconductor alloy is
needed for pre-process layer screening, detector design, and interpretation of detector performance. There is currently a
disparity among the infrared detector community in relating the optical absorption properties to HgCdTe alloy composition
and bandgap energy. This disagreement may stem from a misunderstanding of absorption properties, where existing models were
developed decades ago using either bulk material or material with nonuniform composition. In this work, we have initiated
an investigation of the optical absorption properties of HgCdTe with uniform composition grown by molecular-beam epitaxy (MBE)
with in-situ compositional control via spectroscopic ellipsometry. The absorption properties show unique characteristics in
the bandtail region, with insignificant temperature dependence. The absorption properties above the bandgap suggest a hyperbolic
bandstructure as opposed to the common assumption of a parabolic bandstructure. The temperature dependence of the bandgap
energy shows good agreement to the commonly used expression developed previously by Hansen et al. 相似文献
2.
P. S. Wijewarnsuriya M. Zandian D. D. Edwall W. V. McLevige C. A. Chen J. G. Pasko G. Hildebrandt A. C. Chen J. M. Arias A. I. D’Souza S. Rujirawat S. Sivananthan 《Journal of Electronic Materials》1998,27(6):546-549
The capability of growing state-of-the-art middle wavelength infrared (MWIR)-HgCdTe layers by molecular beam epitaxy (MBE)
on large area silicon substrates has been demonstrated. We have obtained excellent compositional uniformity with standard
deviation of 0.001 with mean composition of 0.321 across 1.5″ radii. R0A as high as 5 × 107 ω-cm2 with a mean value of 7 × 106 Θ-cm2 was measured for cut-off wavelength of 4.8 μm at 77K. Devices exhibit diffusion limited performance for temperatures above
95K. Quantum efficiencies up to 63% were observed (with no anti-reflection coating) for cut-off wavelength (4.8–5.4) μm @
77K. Excellent performance of the fabricated photodiodes on MBE HgCdTe/CdTe/Si reflects on the overall quality of the grown
material in the MWIR region. 相似文献
3.
A. I. D’Souza L. C. Dawson C. Staller P. S. Wijewarnasuriya R. E. Dewames W. V. Mclevige J. M. Arias D. Edwall G. Hildebrandt 《Journal of Electronic Materials》2000,29(6):630-635
Very long wavelength infrared (VLWIR; 15 to 17 μm) detectors are required for remote sensing sounding applications. Infrared
sounders provide temperature, pressure and moisture profiles of the atmosphere used in weather prediction models that track
storms, predict levels of precipitation etc. Traditionally, photoconductive VLWIR (λc >15 μm) detectors have been used for sounding applications. However, photoconductive detectors suffer from performance issues,
such as non-linearity that is 10X – 100X that of photovoltaic detectors. Radiometric calibration for remote sensing interferometry
requires detectors with low non-linearity. Photoconductive detectors also suffer from non-uniform spatial optical response.
Advances in molecular beam epitaxy (MBE) growth of mercury cadmium telluride (HgCdTe) and detector architectures have resulted
in high performance detectors fabricated in the 15 μm to 17 μmm spectral range. Recently, VLWIR (λc ∼ 17 μm at 78 K) photovoltaic large (1000 μm diameter) detectors have been fabricated and measured at flux values targeting
remote sensing interferometry applications. The operating temperature is near 78 K, permitting the use of passive radiators
in spacecraft to cool the detectors. Detector non-AR coated quantum efficiency >60% was measured in these large detectors.
A linear response was measured, while varying the spot size incident on the 1000 μm detectors. This excellent response uniformity,
measured as a function of spot size, implies that low frequency spatial response variations are absent. The 1000 μm diameter,
λc ∼ 17 μm at 78 K detectors have dark currents ∼160 μA at a −100 mV bias and at 78 K. Interfacing with the low (comparable
to the contact and series resistance) junction impedance detectors is not feasible. Therefore a custom pre-amplifier was designed
to interface with the large VLWIR detectors operating in reverse bias. A breadboard was fabricated incorporating the custom
designed preamplifier interfacing with the 1000 μm diameter VLWIR detectors. Response versus flux measurements were made on
the large VLWIR detectors and non-linearity <0.15% was measured at high flux values in the 2.5×1017 to 3.5×1017 ph-cm−2sec−1 range. This non-linearity is an order of magnitude better than for photoconductive detectors. 相似文献
4.
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
5.
K. Moazzami J. Phillips D. Lee S. Krishnamurthy G. Benoit Y. Fink T. Tiwald 《Journal of Electronic Materials》2005,34(6):773-778
HgCdTe remains the material of choice for high-performance infrared (IR) detectors due to its tunable direct bandgap energy
corresponding to the IR spectral region, and the advancement of HgCdTe materials growth and processing technologies. Accurate
knowledge of the HgCdTe optical absorption coefficient is important for IR detector design, layer screening, and device analysis.
The spectral response for IR detectors is dependent on optical absorption above the bandgap energy, where much of the study
of absorption coefficient in HgCdTe has focused on the bandtail region. In this work, the optical absorption coefficient was
studied by theoretical bandstructure calculations and experimental measurements on HgCdTe layers using techniques of IR spectroscopic
ellipsometry and IR transmission. The theoretical and experimental results suggest that the absorption coefficient between
600 cm−1 and 5,000 cm−1 is related to energy relative to bandgap with a fractional exponent between 0.6 and 1, rather than the previously used expressions
relating to a parabolic or hyperbolic bandstructure. The fitting parameters for Hg1-xCdxTe with x=0.22–0.60 are presented to develop a model for the optical absorption coefficient spectra. The calculated detector
spectral response using the new and previously reported absorption coefficient models suggests that next generation IR detectors
employing multilayer structures with graded compositional profiles will likely benefit from this new model. 相似文献
6.
Majid Zandian D. Scott J. Garnett D. D. Edwall J. Pasko M. Farris M. Daraselia J. M. Arias J. Bajaj D. N. B. Hall S. Jacobson G. Luppino S. Parker 《Journal of Electronic Materials》2005,34(6):891-897
Growth of Hg1−xCdxTe by molecular beam epitaxy (MBE) has been under development since the early 1980s at Rockwell Scientific Company (RSC),
formerly the Rockwell Science Center; and we have shown that high-performance and highly reproducible MBE HgCdTe double heterostructure
planar p-on-n devices can be produced with high throughput for various single- and multiplecolor infrared applications. In
this paper, we present data on Hg1−xCdxTe epitaxial layers grown in a ten-inch production MBE system. For growth of HgCdTe, standard effusion cells containing CdTe
and Te were used, in addition to a Hg source. The system is equipped with reflection high energy electron diffraction (RHEED)
and spectral ellipsometry in addition to other fully automated electrical and optical monitoring systems. The HgCdTe heterostructures
grown in our large ten-inch Riber 49 MBE system have outstanding structural characteristics with etch-pit densities (EPDs)
in the low 104 cm−2 range, Hall carrier concentration in low 1014 cm−3, and void density <1000 cm2. The epilayers were grown on near lattice-matched (211)B Cd0.96Zn0.04Te substrates. High-performance mid wavelength infrared (MWIR) devices were fabricated with R0A values of 7.2×106 Ω-cm2 at 110 K, and the quantum efficiency without an antireflection coating was 71.5% for cutoff wavelength of 5.21 μm at 37 K.
For short wavelength infrared (SWIR) devices, an R0A value of 9.4×105 Ω-cm2 at 200 K was obtained and quantum efficiency without an antireflection coating was 64% for cutoff wavelength of 2.61 μm at
37 K. These R0A values are comparable to our trend line values in this temperature range. 相似文献
7.
VLWIR HgCdTe detector current-voltage analysis 总被引:1,自引:0,他引:1
Angelo Scotty Gilmore James Bangs Amanda Gerrish 《Journal of Electronic Materials》2006,35(6):1403-1410
This article details current-voltage characteristics for a very long wavelength infrared (VLWIR) Hg1−x
CdxTe detector from Raytheon Vision Systems with a cutoff wavelength of 20.0 μm at 28 K. In this article, the VLWIR detector
diode currents are modeled as a function of bias and temperature. This in-depth current model includes diffusion, band-to-band
tunneling, trap-assisted tunneling (TAT), and shunt currents. The trap density has been extracted from the modeled TAT component
of the current and was revealed to be relatively temperature-independent. An attempted incorporation of VLWIR detector susceptibility
to stress has also been included through variation of the model parameter associated with the p-n junction electric field
strength. This field variation accounts for stress induced piezoelectric fields. The current in this VLWIR detector was found
to be diffusion-limited under much of the temperature and bias ranges analyzed. This modeling allows the scrutiny of both
the dominant current-limiting mechanism and the magnitudes of the various current components as a function of both bias and
temperature, allowing the straightforward determination of the ideal operating conditions for a given detector. 相似文献
8.
甚长波红外波段富含大气湿度、CO2含量及云层结构和温度轮廓等大量信息,是大气遥感的重要组成部分。设计了一种3232甚长波红外焦平面阵列,采用在ZnCdTe衬底上液相外延生长的As掺杂p型材料上进行B+离子注入形成光敏元,通过铟柱倒焊技术和带有改进型背景抑制结构的读出电路互联,制成截止波长达到14 m的焦平面器件。该红外焦平面器件像元面积为60 m60 m,工作温度在50 K温度下。测试结果显示:读出电路性能良好,焦平面黑体响应率达到1。35107V/W,峰值探测率为2。571010 cmHz1/2/W,响应率非均匀性约为45%,盲元率小于12%。 相似文献
9.
Independently accessed back-to-back HgCdTe photodiodes: A new dual-band infrared detector 总被引:3,自引:0,他引:3
M. B. Reine P. W. Norton R. Starr M. H. Weiler M. Kestigian B. L. Musicant P. Mitra T. Schimert F. C. Case Lb. Bhat H. Ehsani V. Rao 《Journal of Electronic Materials》1995,24(5):669-679
We report the first data for a new two-color HgCdTe infrared detector for use in large dual-band infrared focal plane arrays
(IRFPAs). Referred to as the independently accessed back-to-back photodiode structure, this novel dual-band HgCdTe detector
provides independent electrical access to each of two spatially collocated back-to-back HgCdTe photodiodes so that true simultaneous
and independent detection of medium wavelength (MW, 3–5 μm) and long wavelength (LW, 8–12 μm) infrared radiation can be accomplished.
This new dual-band detector is directly compatible with standard backside-illuminated bump-interconnected hybrid HgCdTe IRFPA
technology. It is capable of high fill factor, and allows high quantum efficiency and BLIP sensitivity to be realized in both
the MW and LW photodiodes. We report data that demonstrate experimentally the key features of this new dual-band detector.
These arrays have a unit cell size of 100 x 100 μm2, and were fabricated from a four-layer p-n-N-P HgCdTe film grown in situ by metalorganic chemical vapor deposition on a CdZnTe
substrate. At 80K, the MW detector cutoff wavelength is 4.5 μm and the LW detector cutoff wavelength is 8.0 μm. Spectral crosstalk
is less than 3%. Data confirm that the MW and LW photodiodes are electrically and radiometrically independent. 相似文献
10.
Status of the MBE technology at leti LIR for the manufacturing of HgCdTe focal plane arrays 总被引:2,自引:0,他引:2
P. Ferret J. P. Zanatta R. Hamelin S. Cremer A. Million M. Wolny G. Destefanis 《Journal of Electronic Materials》2000,29(6):641-647
This paper presents recent developments that have been made in Leti Infrared Laboratory in the field of molecular beam epitaxy
(MBE) growth and fabrication of medium wavelength and long wavelength infrared (MWIR and LWIR) HgCdTe devices. The techniques
that lead to growth temperature and flux control are presented. Run to run composition reproducibility is investigated on
runs of more than 15 consecutively grown layers. Etch pit density in the low 105 cm−2 and void density lower than 103 cm−2 are obtained routinely on CdZnTe substrates. The samples exhibit low n-type carrier concentration in the 1014 to 1015 cm−3 range and mobility in excess of 105 cm2/Vs at 77 K for epilayers with 9.5 μm cut-off wavelength. LWIR diodes, fabricated with an-on-p homojunction process present
dynamic resistance area products which reach values of 8 103 Ωcm2 for a biased voltage of −50 mV and a cutoff wavelength of 9.5 μm at 77 K. A 320 × 240 plane array with a 30 μm pitch operating
at 77 K in the MWIR range has been developed using HgCdTe and CdTe layers MBE grown on a Germanium substrate. Mean NEDT value
of 8.8 mK together with an operability of 99.94% is obtained. We fabricated MWIR two-color detectors by the superposition
of layers of HgCdTe with different compositions and a mixed MESA and planar technology. These detectors are spatially coherent
and can be independently addressed. Current voltage curves of 60 × 60 μm2 photodiodes have breakdown voltage exceeding 800 mV for each diode. The cutoff wavelength at 77 K is 3.1 μm for the MWIR-1
and 5 μm for the MWIR-2. 相似文献
11.
甚长波指的是波长大于14 m的波段,该波段富含大量的信息,包括大气中的湿度和CO2的含量,以及云层的结构和温度的轮廓,这些对大气遥感探测是必须的。采用在CdZnTe衬底上液相外延生长的As掺杂p型材料上进行B+离子注入形成平面结,制成了在液氮温度下,截止波长达到14 m的单元变面积结构和小的焦平面器件。测试结果显示,甚长波器件有反向的开启现象,可能是甚长波器件表面发生反型造成的。单元变面积器件的测试结果显示,甚长波表面电流与体电流是可以比拟的,即表面漏电较大。而变温测试发现,甚长波器件在温度低于50 K时,隧穿电流占主导。在60 m60 m中心距的小面阵器件中,50 m50 m的光敏元I-V特性最差。 相似文献
12.
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
13.
This paper proposes a development of n-on-p structures for realizing very long wavelength infrared (VLWIR) detector arrays
on mercury cadmium telluride (HgCdTe) epitaxial layers grown on Si substrates. It is shown from a comparative study of zero-bias
resistance-area product (R0A) of diodes in n-on-p and p-on-n configurations that the n-on-p structure has promising potential to control contribution
of dislocations, without actually reducing dislocation density below the current level (mid-106 cm−2) of HgCdTe/Si material technology. The resulting gain will be in terms of both higher numerical magnitudes of R0A and its reduced scatter. 相似文献
14.
R. Haakenaasen H. Steen T. Lorentzen L. Trosdahl-Iversen A. D. Van Rheenen H. Syversen 《Journal of Electronic Materials》2002,31(7):710-714
Planar mid-wavelength infrared (MWIR) and long-wavelength infrared (LWIR) photodiodes were fabricated by ion milling molecular
beam epitaxy (MBE) CdxHg1−xTe (CMT) layers with and without compositional grading in the layer. Linear arrays with 32 and 64 diodes, as well as test
diodes of varying size, were fabricated. Good quantum efficiencies were measured, and MWIR diodes, with cutoff wavelength
λCO=4.5 μm, had zero-bias resistance-area values (R0A) in excess of 1×107 Ωcm2, whereas LWIR diodes with λCO=8.9−9.3 μm had R0A=3×102 Ωcm2 at 77 K. Comparison between a limited number of layers indicates that in layers with a gradient the RA values are a factor
of ∼10 larger, and possibly more uniform, than in layers without a gradient. 相似文献
15.
P.Y. Emelie S. Velicu C.H. Grein J.D. Phillips P.S. Wijewarnasuriya N.K. Dhar 《Journal of Electronic Materials》2008,37(9):1362-1368
The general approach and effects of nonequilibrium operation of Auger-suppressed HgCdTe infrared photodiodes are well understood.
However, the complex relationships of carrier generation and dependencies on nonuniform carrier profiles in the device prevent
the development of simplistic analytical device models with acceptable accuracy. In this work, finite element methods are
used to obtain self-consistent steady-state solutions of Poisson’s equation and the carrier continuity equations. Experimental
current–voltage characteristics between 120 K and 300 K of HgCdTe Auger-suppressed photodiodes with cutoff wavelength of λ
c = 10 μm at 120 K are fitted using our numerical model. Based on this fitting, we study the lifetime in the absorber region, extract
the current mechanisms limiting the dark current in these photodiodes, and discuss design and fabrication considerations in
order to optimize future HgCdTe Auger-suppressed photodiodes. 相似文献
16.
J. Beck C. Wan M. Kinch J. Robinson P. Mitra R. Scritchfield F. Ma J. Campbell 《Journal of Electronic Materials》2006,35(6):1166-1173
Electron injection avalanche photodiodes in short-wave infrared (SWIR) to long-wave infrared (LWIR) HgCdTe show gain and excess
noise properties indicative of a single ionizing carrier gain process. The result is an electron avalanche photodiode (EAPD)
with “ideal” APD characteristics including near noiseless gain. This paper reports results obtained on long-, mid-, and short-wave
cutoff infrared Hg1−xCdxTe EAPDs (10 μm, 5 μm, and 2.2 μm) that use a cylindrical “p-around-n” front side illuminated n+/n-/p geometry that favors
electron injection into the gain region. These devices are characterized by a uniform, exponential, gain voltage characteristic
that is consistent with a hole-to-electron ionization coefficient ratio, k=αh/αe, of zero. Gains of greater than 1,000 have been measured in MWIR EAPDS without any sign of avalanche breakdown. Excess noise
measurements on midwave infrared (MWIR) and SWIR EAPDs show a gain independent excess noise factor at high gains that has
a limiting value less than 2. At 77 K, 4.3-μm cutoff devices show excess noise factors of close to unity out to gains of 1,000.
A noise equivalent input of 7.5 photons at a 10-ns pulsed signal gain of 964 measured on an MWIR APD at 77 K provides an indication
of the capability of this new device. The excess noise factor at room temperature on SWIR EAPDs, while still consistent with
the k=0 operation, approaches a gain independent limiting value of just under 2 because of electron-phonon interactions expected
at room temperature. The k=0 operation is explained by the band structure of the HgCdTe. Monte Carlo modeling based on the
band structure and scattering models for HgCdTe predict the measured gain and excess noise behavior. 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. 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
19.
O. Gravrand E. De Borniol S. Bisotto L. Mollard G. Destefanis 《Journal of Electronic Materials》2007,36(8):981-987
This paper aims at studying the feasibility of very long infrared wavelength (VLWIR) (12–18 μm) focal plane arrays using n-on-p planar ion-implanted technology. To explore and analyze the feasibility of such VLWIR detectors, a set of four Cd
x
Hg1−x
Te LPE layers with an 18 μ cutoff at 50 K has been processed at Defir (LETI/LIR–Sofradir joint laboratory), using both our “standard” n-on-p process and our improved low dark current process. Several 320 × 256 arrays, 30-μm pitch, have been hybridized on standard Sofradir readout circuits and tested. Small dimension test arrays characterization
is also presented. Measured photonic currents with a 20°C black body suggest an internal quantum efficiency above 50%. Typical
I(V) curves and thermal evolution of the saturation current are discussed, showing that standard photodiodes remain diffusion
limited at low biases for temperatures down to 30 K. Moreover, the dark current gain brought by the improved process is clearly
visible for temperatures higher than 40 K. Noise measurements are also discussed showing that a very large majority of detectors
appeared background limited under usual illumination and biases. In our opinion, such results demonstrate the feasibility
of high-performance complex focal plane arrays in the VLWIR range at medium term. 相似文献
20.
Angelo Scotty Gilmore James Bangs Amanda Gerrish 《Journal of Electronic Materials》2005,34(6):913-921
An automated iterative nonlinear fitting program has been developed to model current-voltage (I–V) data measured on HgCdTe
infrared (IR) detector diodes. This model includes the ideal diode diffusion, generation-recombination, band-to-band tunneling,
trap-assisted tunneling (TAT), and avalanche breakdown as potential current limiting mechanisms in an IR detector diode. The
modeling presented herein allows one to easily distinguish, and more importantly to quantitatively compare, the amount of
influence each current limiting mechanism has on various detectors’ I–V characteristics. Longer cutoff wavelength detectors
often exhibit significant current limitations due to tunneling processes. The temperature dependence of these tunneling characteristics
is thoroughly investigated for two diodes. 相似文献