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1.
J. M. Arias J. G. Pasko M. Zandian S. H. Shin G. M. Williams L. O. Bubulac R. E. De Wames W. E. Tennant 《Journal of Electronic Materials》1993,22(8):1049-1053
We recently succeeded in fabricating planar Hg1−yCdyTe/Hg1−xCdxTe (x<y) heterostructure photodiodes with the p-on-n configuration. Here we discuss early results in detail and present new
results on an expanded range of infrared operation. The material used for this demonstration was grown by molecular beam epitaxy
on lattice-matched CdZnTe substrates. The p-on-n planar devices consist of an arsenic-doped p-type epilayer (y∼0.28) atop
a long wavelength infrared n-type epilayer (x=0.22–0.23). The planar junctions were formed by selective pocket diffusion of
arsenic deposited on the surface by ion implantation. Detailed analysis of the current-voltage characteristics of these diodes
as a function of temperature shows that they have high performance and that their dark currents are diffusion-limited down
to 52K. Low frequency noise measurements at a reverse bias voltage of 50 mV resulted in noise current values (at 1 Hz) as
low as 1×10−14 amps/Hz0.5 at 77K. Average RoA values greater than 106 Ω-cm2 at 40K were obtained for these devices with cut-off wavelength values in the 10.6 to 12 μm range. Seventy percent of these
devices have RoA values greater than 105 Ω-cm2 at 40K; further studies are needed to improve device uniformity. These results represent the first demonstration that high
performance long wavelength infrared devices operating at 40K can be made using HgCdTe material grown by a vapor phase epitaxy
growth technique. 相似文献
2.
Majid Zandian J. D. Garnett R. E. Dewames M. Carmody J. G. Pasko M. Farris C. A. Cabelli D. E. Cooper G. Hildebrandt J. Chow J. M. Arias K. Vural Donald N. B. Hall 《Journal of Electronic Materials》2003,32(7):803-809
We report on Hg1−xCdxTe mid-wavelength infrared (MWIR) detectors grown by molecular-beam epitaxy (MBE) on CdZnTe substrates. Current-voltage (I-V)
characteristics of HgCdTe-MWIR devices and temperature dependence of focal-plane array (FPA) dark current have been investigated
and compared with the most recent InSb published data. These MWIR p-on-n Hg1−xCdxTe/CdZnTe heterostructure detectors give outstanding performance, and at 68 K, they are limited by diffusion currents. For
temperatures lower than 68 K, in the near small-bias region, another current is dominant. This current has lower sensitivity
to temperature and most likely is of tunneling origin. High-performance MWIR devices and arrays were fabricated with median
RoA values of 3.96 × 1010 Ω-cm2 at 78 K and 1.27 × 1012 Ω-cm2 at 60 K; the quantum efficiency (QE) without an antireflection (AR) coating was 73% for a cutoff wavelength of 5.3 μm at
78 K. The QE measurement was performed with a narrow pass filter centered at 3.5 μm. Many large-format MWIR 1024 × 1024 FPAs
were fabricated and tested as a function of temperature to confirm the ultra-low dark currents observed in individual devices.
For these MWIR FPAs, dark current as low as 0.01 e−/pixel/sec at 58 K for 18 × 18 μm pixels was measured. The 1024 × 1024 array operability and AR-coated QE at 78 K were 99.48%
and 88.3%, respectively. A comparison of these results with the state-of-the-art InSb-detector data suggests MWIR-HgCdTe devices
have significantly higher performance in the 30–120 K temperature range. The InSb detectors are dominated by generation-recombination
(G-R) currents in the 60–120 K temperature range because of a defect center in the energy gap, whereas MWIR-HgCdTe detectors
do not exhibit G-R-type currents in this temperature range and are limited by diffusion currents. 相似文献
3.
P. S. Wijewarnasuriya M. Zandian D. B. Young J. Waldrop D. D. Edwall W. V. Mclevige D. Lee J. Arias A. I. D’Souza 《Journal of Electronic Materials》1999,28(6):649-653
Long wavelength infrared molecular beam epitaxy (MBE) grown p-on-n Hg1−xCdxTe double layer planar heterostructure (DLPH) detectors have been characterized to determine the dominant mechanisms limiting
their performance. Material defects have been identified as critical factors that limit 40K performance operability. This
effort has concentrated on identifying microscopic defects, etch pit density (EPD) and relating these defects to the device
performance. Visual inspection indicates defect densities as high as 105 per cm2 with a spatial extent as observed by atomic force microscope in the range of micrometers extending several micrometers beneath
the surface. At high EPD values (greater than low 106 cm−2) zero bias resistance (R0) at 40K decreases as roughly as the square of the EPD. At 78K, however, measured R0 is not affected by the EPD up to densities as high as mid-106 cm−2. Visual defects greater than 2–3 μm than ∼2 μm in size (micro-void defects) result in either a single etch pit or a cluster
of etch pits. Large variations in a cross-wafer etch pit distribution are most likely a major contributor to the observed
large spreads in 40K R0. This study gives some insight to the present limitation to achieve higher performance and high operability for low temperature
infrared applications on MBE grown HgCdTe material. 相似文献
4.
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
5.
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
6.
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
7.
S. Velicu C.H. Grein J. Zhao Y. Chang S.-Y. An A. Yadav K. Pipe W. Clark 《Journal of Electronic Materials》2008,37(9):1504-1508
We present a study on the thermoelectric properties of n-type Hg0.75Cd0.25 Te/Hg0.7Cd0.3Te superlattices (SLs). This material system was chosen because HgCdTe is the primary material used in high-performance infrared
imaging applications. HgCdTe-based devices can be directly grown on Hg1−x
Cd
x
Te/Hg1−y
Cd
y
Te SL coolers using advanced growth methods such as molecular-beam epitaxy (MBE), making the monolithic integration of infrared
sensors and thermoelectric elements possible. Also, the thermoelectric figure of merit ZT for Hg0.75Cd0.25Te/Hg0.7Cd0.3Te SLs is predicted to reach values of 2.09, more than two times greater than that achieved in the best thermoelectric devices
based on bulk Bi2Te3. This large ZT is due to the unique and superior electrical and thermal properties of the HgCdTe system, which has not yet been experimentally
explored in any great depth as a thermoelectric material. We used a Riber 32P MBE system equipped with a Hg valved cell, reflection
high-energy electron diffraction, infrared pyrometer and in situ spectroscopic ellipsometry to grow the thermoelectric structures. MBE was chosen as a growth technique since it allows for
the lowest growth temperature compared with other methods, which limits interdiffusion at the interfaces, thereby allowing
for a precise control over electrical and thermal properties. Thermal devices were fabricated using standard photolithography
and etching techniques. Thermal properties were evaluated using a differential technique. A thermal conductivity of 0.82 ± 0.07 W/m K
and a Seebeck coefficient of 811 ± 150 μV/K were measured. Using a measured value of 0.017 Ω cm for the resistivity, an upper bound ZT of 1.4 is estimated.
An erratum to this article can be found at 相似文献
8.
M.F. Vilela S.F. Harris R.E. Kvaas A.A. Buell M.D. Newton K.R. Olsson D.D. Lofgreen S.M. Johnson 《Journal of Electronic Materials》2009,38(8):1755-1763
In this paper, we show the versatility of using molecular-beam epitaxy (MBE) for the growth of the mercury cadmium telluride
(HgCdTe) system. Abrupt composition profiles, changes in doping levels or switching doping types are easily performed. It
is shown that high-quality material is achieved with Hg(1–x)Cd
x
Te grown by MBE from a cadmium mole fraction of x = 0.15 to x = 0.72. Doping elements incorporation as low as 1015 cm−3 for both n-type and p-type material as well as high incorporation levels >1018 cm−3 for both carrier types were achieved. X-ray curves, secondary-ion mass spectrometry (SIMS) data, Hall data, the influence
of doping incorporation with cadmium content and growth rate, etch pit density (EPD), composition uniformity determined from
Fourier-transform infrared (FTIR) transmission spectro- scopy, and surface defect maps from low to high x values are presented to illustrate the versatility and quality of HgCdTe material grown by MBE. All data presented in this
work are from layers grown on silicon (112) substrate. 相似文献
9.
S. Dvoretsky N. Mikhailov Yu. Sidorov V. Shvets S. Danilov B. Wittman S. Ganichev 《Journal of Electronic Materials》2010,39(7):918-923
We zone-engineered HgCdTe/HgTe/HgCdTe quantum wells (QWs) using the molecular-beam epitaxy (MBE) method with in situ high-precision ellipsometric control of composition and thickness. The variations of ellipsometric parameters in the ψ–Δ
plane were represented by smooth broken curves during HgTe QW growth with abrupt composition changes. The form of the spiral
fragments and their extensions from fracture to fracture revealed the growing layer composition and its thickness. Single
and multiple (up to 30) Cd
x
Hg1−x
Te/HgTe/Cd
x
Hg1−x
Te QWs with abrupt changes of composition were grown reproducibly on (013) GaAs substrates. HgTe thickness was in the range
of 16 nm to 22 nm, with the central portion of Cd
x
Hg1−x
Te spacers doped by In to a concentration of 1014 cm−3 to 1017 cm−3. Based on this research, high-quality (013)-grown HgTe QW structures can be used for all-electric detection of radiation
ellipticity in a wide spectral range, from far-infrared (terahertz radiation) to mid-infrared wavelengths. Detection was demonstrated
for various low-power continuous-wave (CW) lasers and high-power THz pulsed laser systems. 相似文献
10.
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
11.
M. J. Bevan L. A. Almeida W. M. Duncan H. D. Shih 《Journal of Electronic Materials》1997,26(6):502-506
A systematic study of the effect of measurement perturbation on in situ monitoring of the composition of molecular beam epitaxially (MBE) grown Hg1−xCdxTe using spectroscopic ellipsometry was carried out. Of the five variables investigated, which included angle of incidence,
wavelength of the light beam, modulator rotation, analyzer rotation, and modulator amplitude, the angle of incidence and the
modulator rotation had the strongest effect on the in situ Hg1−xCdxTe composition monitoring process. A wobble-free sample manipulator was installed to reduce the impact of these two variables.
With these improvements, the spectroscopic ellipsometer is now routinely used to monitor Hg
1−xCdxTe compositions during MBE growth of heterostructures and is a useful tool in diagnosing growth-related problems. Examples
are included for both application areas, that include the control of the interface between Hg1−xCdxTe layers of different compositions, i.e. device engineering. 相似文献
12.
Molecular beam epitaxial HgCdTe material characteristics and device performance: Reproducibility status 总被引:1,自引:0,他引:1
J. Bajaj J. M. Arias M. Zandian J. G. Pasko L. J. Kozlowski R. E. De Wames W. E. Tennant 《Journal of Electronic Materials》1995,24(9):1067-1076
Extensive material, device, and focal plane array (FPA) reproducibility data are presented to demonstrate significant advances
made in the molecular beam epitaxial (MBE) HgCdTe technology. Excellent control of the composition, growth rate, layer thickness,
doping concentration, dislocation density, and transport characteristics has been demonstrated. A change in the bandgap is
readily achieved by adjusting the beam fluxes, demonstrating the flexibility of MBE in responding to the needs of infrared
detection applications in various spectral bands. High performance of photodiodes fabricated on MBE HgCdTe layers reflects
on the overall quality of the grown material. The photodiodes were planar p-on-n junctions fabricated by As ion-implantation
into indium doped, n-type, in situ grown double layer heterostructures. At 77K, diodes fabricated on MBE Hg1−xCdxTe with x ≈ 0.30 (λco
≈ 5.6 μm), x ≈ 0.26 (λco
≈ 7 μm), x ≈ 0.23 (λco ≈ 10 μm) show R0A products in excess of 1 x 106 ohm-cm2, 7 x 105 ohm-cm2, and 3 x 102 ohm-cm2, respectively. These devices also show high quantum efficiency. As a means to assess the uniformity of the MBE HgCdTe material,
two-dimensional 64 x 64 and 128 x 128 mosaic detector arrays were hybridized to Si multiplexers. These focal plane arrays
show an operability as high as 97% at 77K for the x ≈ 0.23 spectral band and 93% at 77K for the x ≈ 0.26 spectral band. The
operability is limited partly by the density of void-type defects that are present in the MBE grown layers and are easily
identified under an optical microscope. 相似文献
13.
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
14.
S. M. Johnson J. L. Johnson W. J. Hamilton D. B Leonard T. A. Strand E. A. Patten J. M. Peterson J. H. Durham V. K. Randall T. J. deLyon J. E. Jensen M. D. Gorwitz 《Journal of Electronic Materials》2000,29(6):680-686
As the number of bands and the complexity of HgCdTe multicolor structures increases, it is desirable to minimize the lattice
mismatch at growth interfaces within the device structure in order to reduce or eliminate mismatch dislocations at these interfaces
and potential threading dislocations that can degrade device performance. To achieve this we are investigating the use of
Hg1−x−yCdxZnyTe quaternary alloys which have an independently tunable lattice constant and bandgap. Lattice matching in Hg1−x−yCdxZnyTe structures can be achieved using small additions of Zn (y<0.015) to HgCdTe ternary alloys. We have investigated some of
the basic properties of Hg1−x−yCdxZnyTe materials with x≈0.31 and 0≤y≤0.015. The quaternary layers were grown on (112)CdZnTe substrates using MBE and the amount
of Zn in the layers was determined from calibrated SIMS measurements. As expected, the lattice constant decreased and the
bandgap increased as Zn was added to HgCdTe to form Hg1−x−yCdxZnyTe. Hall-effect results for both n-type (In) and p-type (As) Hg1−x−yCdxZnyTe layers were very similar to HgCdTe control samples. We have also utilized x-ray rocking curve measurements with (246) asymmetric
reflections as a novel sensitive technique to determine the correct amount of Zn needed to achieve lattice matching at an
interface. MWIR/LWIR n-p-n two-color triple-layer heterojunction structures were grown to evaluate the effects of minimizing
the lattice mismatch between the widest bandgap p-type collector layer, using Hg1−x−yCdxZnyTe, and the HgCdTe MWIR and LWIR collector layers and compared to structures that did not incorporate the quaternary. Sequential
mode two-color detectors were fabricated using a 256 × 256, 30 μm unit cell design. There were several interesting findings.
Macro defects predominantly affected the LWIR band (Band 2) operability and had little effect on the MWIR band (Band 1). The
incorporation of Hg1−x−yCdxZnyTe p-type collector layers had little effect on MWIR detector performance, but overall the LWIR performance was generally
better. These initial detector results indicate that the use of Hg1−x−yCdxZnyTe alloys in multicolor detector structures are potentially promising and should be pursued further. 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.
M. Zandian J. M. Arias J. Bajaj J. G. Pasko L. O. Bubulac R. E. Dewames 《Journal of Electronic Materials》1995,24(9):1207-1210
Characterization of defects in Hg1−xCdxTe compound semiconductor is essential to reduce intrinsic and the growth-induced extended defects which adversely affect
the performance of devices fabricated in this material system. It is shown here that particulates at the substrate surface
act as sites where void defects nucleate during Hg1−xCdxTe epitaxial growth by molecular beam epitaxy. In this study, we have investigated the effect of substrate surface preparation
on formation of void defects and established a one-to-one correlation. A wafer cleaning procedure was developed to reduce
the density of such defects to values below 200 cm−2. Focal plane arrays fabricated on low void density materials grown using this new substrate etching and cleaning procedure
were found to have pixel operability above 98.0%. 相似文献
17.
The electrical effects of dislocations has been studied by modeling zero-bias resistance-area product (R0A) of long wavelength infrared diodes fabricated in molecular beam epitaxy (MBE)-grown HgCdTe-Si epitaxial films. Results
show that dislocations influence both 40 K and 78 K R0A products in high dislocation density (HgCdTe/Si) material. In low dislocation density samples (HgCdTe/CdZnTe), the variations
in 78 K R0A are limited by the composition (x) variations in Hg1-xCdxTe material, whereas dislocation contribution dominates the variations at 40 K. The origin of relatively large spread in 40
K R0A in both types of samples is traced to the statistical variations in the core charges of dislocations. It is concluded that
additional alternatives besides the reduction of dislocation density (such as control of core charges), may also need attention
in order to make Si a viable substrate material for the growth of HgCdTe epitaxial layers suitable for devices operating at
40 K. 相似文献
18.
A. I. D’Souza P. S. Wijewarnasuriya R. E. Dewames G. Hildebrandt J. Bajaj D. D. Edwall J. G. Pasko J. M. Arias 《Journal of Electronic Materials》1999,28(6):611-616
Excess low frequency noise is investigated for the first time in infrared MBE grown LWIR Hg1−xCdxTe double layer planar heterostructure (DLPH) detectors grown on lattice matched substrates. LWIR detectors having R0Aopt values at 40K in the 101–107 Θ-cm2 range have been characterized as a function of temperature between 120 and 20K. Detectors with R0Aopt≥103Θ-cm2 at 40K have theoretical diffusion limited performance down to 78K and detectors with R0Aopt ≥105 Θ-cm2 at 40K are within a factor of two of theoretical diffusion limited performance for T>65K. Activation energies extracted from
noise (Vd=−100 mV) and dark current (Vd=−100 mV) vs temperature measurements were detector dependent. The activation energy for detectors with R0Aopt≈106 Θ-cm2 at 40K is ∼0.90*Eg to 0.99*Eg. The noise measured between 78 and 105K in the intermediate performance (R0Aopt∼103–104 Θ-cm2 at 40K) detectors are higher than the noise measured in the higher performance (R0Aopt∼105–107 Θ-cm2) detectors. In addition, the excess low frequency noise and the dark current at −100 mV in the intermediate and poor (R0Aopt∼101 Θ-cm2) performance detectors are temperature independent. For each detector measured, the activation energy extracted from noise
(Vd=−100 mV) vs temperature measurements is equal to the activation energy extracted from the total dark current (Vd=−100 mV) vs temperature measurements. For different dark current mechanisms, the excess low frequency noise varies with temperature
and also with area within statistical accuracy in the same manner as the total dark current through the detector. At 78K,
the Tobin14 expression holds in the general sense for equal area detectors dominated by different current mechanisms and also for detectors
with a wide range of implant dimensions (Aimp=3.85×10−7 cm2 to Aimp=6.25×10−4 cm2). Following measurements, the detectors were stripped of the passivation and overlaying metal layers and dressed by a defect
etch to reveal defects in each detector. A correlation among noise, leakage current and defect type has been determined for
each detector. 相似文献
19.
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
20.
Epitaxial layers of Hg1−xCdx Te were grown on CdTe substrates by the chemical vapor transport technique using Hgl2 as a transport agent. The epilayers were of nearly uniform composition both laterally and to a depth of about one-half of
the layer thickness. By comparison, the composition varied continuously throughout the depth of the layer for epilayers grown
by the physical vapor transport technique. Layers were grown both p- and n-type with carrier concentrations on the order of
1017 cm−3. Low-temperature annealing was used to convert the p-type layers into n-type. The room-temperature carrier mobilities of
as-grown and converted n-type layers ranged from 103 to 104 cm2/V-s depending on the composition and are comparable to previous literature values for undoped Hg1−xCdxTe crystals. 相似文献