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1.
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
2.
Heinrich Figgemeier Martin Bruder Karl-Martin Mahlein Richard Wollrab Johann Ziegler 《Journal of Electronic Materials》2003,32(7):588-591
HgCdTe detector performance and yield are strongly dependant on CdZnTe substrate and HgCdTe epilayer properties, and on key
device processes, especially for 8–12 μm application. Due to the correlation and optimization between these figures and diode
performance, AIM has developed a mature HgCdTe technology for superior detector performance and high production rate. To meet
high yield and performance for long wavelength (LW) HgCdTe diodes, dislocation densities of < 1 × 10t cm−2 both in substrate and epilayer have to be ensured. By a unique AIM substrate growth process, dislocation densities of 2 ×
104-9 × 104 cm−2 are achieved for all substrates and epilayers (100% yield). The etch pit density (EPD) on 〈111〉 epilayers is revealed by
an AIM proprietary etching procedure. One critical effect is the dislocations in the diode area, which can originate from
the substrate and epilayer growth and the subsequent device processes, respectively. Our studies have shown that device processes
can cause additional dislocations in the diode area.
Diode yield was clearly improved by a combination of wet and dry etching for diode contact etching. 相似文献
3.
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
4.
C. D. Maxey C. L. Jones N. E. Metcalfe R. Catchpole M. R. Houlton A. M. White N. T. Gordon C. T. Elliott 《Journal of Electronic Materials》1996,25(8):1276-1285
Band gap engineered Hg1−xCdxTe (MCT) heterostructures should lead to detectors with improved electro-optic and radiometric performance at elevated operating
temperatures. Growth of such structures was accomplished using metalorganic vapor phase epitaxy (MOVPE). Acceptor doping with
arsenic (As), using phenylarsine (PhAsH2), demonstrated 100% activation and reproducible control over a wide range of concentrations (1 × 1015 to 3.5 × 1017 cm−3). Although vapor from elemental iodine showed the suitability of iodine as a donor in MC.T, problems arose while controlling
low donor concentrations. Initial studies using ethyliodide (EtI) demonstrated that this source could be used successfully
to dope MCT, yielding the properties required for stable heterostructure devices, i.e. ≈100% activation, no memory problems
and low diffusion coefficient. Cryogenic alkyl cooling or very high dilution factors were required to achieve the concentrations
needed for donor doping below ≈1016cm−3 due to the high vapor pressure of the alkyl. A study of an alternative organic iodide source, 2-methylpropyliodide (2 MePrI),
which has a much lower vapor pressure, improved control of low donor concentrations. 2 MePrI demonstrated the same donor source
suitability as EtI and was used to control iodine concentrations from ≈ 1 × 1015 to 5 × 1017cm−3. The iodine from both sources only incorporated during the CdTe cycles of the interdiffused multilayer process (IMP) in a
similar manner to both elemental iodine and As from PhAsH2. High resolution secondary ion mass spectroscopy analysis showed that IMP scale modulations can still be identified after
growth. The magnitude of these oscillations is consistent with a diffusion coefficient of≈7 × 10−16cm2s−1 for iodine in MC.T at 365°C. Extrinsically doped device heterostructures, grown using 2 MePrI, have been intended to operate
at elevated temperatures either for long wavelength (8–12 smm) equilibrium operation at 145K or nonequilibrium operation at
190 and 295K in both the 3–5 μ and 8–12 μ wavelength ranges. Characterization of such device structures will be discussed.
Linear arrays of mesa devices have been fabricated in these layers. Medium wave nonequilibrium device structures have demonstrated
high quantum efficiencies and R0A = 37 Ωcm2 for λco = 4.9 μ at 190K. 相似文献
5.
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
6.
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
7.
R. Sewell C. A. Musca J. M. Dell L. Faraone K. Józwikowski A. Rogalski 《Journal of Electronic Materials》2003,32(7):639-645
The steady-state lifetime of photogenerated minority carriers has been investigated in heterostructure HgCdTe devices fabricated
on molecular-beam epitaxy (MBE) grown material. A wider bandgap capping layer (Hg(1−x)Cd(x)Te, x = 0.44) was grown on a narrower bandgap absorbing layer (Hg(1−x)Cd(x)Te, x = 0.32, λco,80K = 4.57 μm) material in an uninterrupted MBE growth to create an abrupt heterointerface. Steady-state lifetime as a function
of temperature over the range 80–300 K was extracted from photoconductive responsivity at an optical wavelength corresponding
to the peak responsivity at that temperature. At 80 K, the photoconductors exhibit a specific detectivity of 4.5 × 1011 cm Hz−1/2W−1 (chopping frequency of 1 kHz). For each measurement temperature, the steady-state excess carrier lifetime determined experimentally
was compared to the theoretical bulk lifetime for material with x = 0.32 and effective n-type doping density of 3.7 × 1014 cm−3. Theoretical calculations of the Auger-1 lifetime based on expressions developed by Pratt et al. were not able to account
for the reduction in lifetime observed at temperatures above 180 K. Two approaches have been attempted to resolve this discrepancy:
A semiempirical expression for Auger lifetime attributed to Meyer et al. was used to fit to the data, with the Auger coefficient
γ as a fitting parameter. However, the resulting Auger coefficient found in this work is more than an order of magnitude higher
than that reported previously. Alternatively, the reduction in effective lifetime above 180 K may be understood as a “loss”
of carriers from the narrow bandgap absorbing layer that are promoted across the potential barrier in the conduction band
into a low lifetime, wider bandgap capping layer. The reduction in lifetime as a function of inverse temperature for temperatures
above 180 K may be fitted by a “cap lifetime” that has an activation energy equal to the change in bandgap across the heterostucture
and scaled by a fitting constant. 相似文献
8.
The characteristics of PbTe films grown by molecular beam epitaxy (MBE) have been investigated. These films were grown on
(100) oriented Tl-doped PbTe substrates under UHV conditions (~5×l0−9 Torr during deposition). Substrate surface contamination levels were studied with Auger electron spectroscopy. Oxygen, the
dominant impurity observed, is rapidly thermally desorbed from PbTe, but is stable on Pb1−xSnxTe up to at least 410°C. Carrier concentration and mobility were measured with the Van der Pauw technique. The electron mobility
increased strongly with increasing film thickness, varying from 4,000 to 14,000 cm2/volt-sec as the thickness increased from 2.0 to 7.3 μn. The film surface also became smoother with increasing film thickness.
These results suggest the need for a buffer layer in a laser structure. Lasers grown with 6 μm thick buffer layers have exhibited
extremely low threshold current densities (40 A/cm2 at 13 K) and very high junction resistancearea products at zero-bias (0.7 Ω−cm2 at 77 K), indicative of very high junction quality. 相似文献
9.
S. P. Tobin M. H. Weiler M. A. Hutchins T. Parodos P. W. Norton 《Journal of Electronic Materials》1999,28(6):596-602
With good composition control in both p-type cap and n-type base LPE layers, it is possible to make barrier-free two-layer
P-on-n HgCdTe heterojunction photodiodes with very long cutoff wavelengths. Diode arrays with good RoA operability, good quantum efficiency, and low 1/f noise at 60K have been demonstrated at cutoff wavelengths to 16.3μm. The
diode performance continues to improve at lower temperatures, following a diffusion-current trend to at least 35K. Measured
RoA values of 2×105 ohm-cm2 for an 18 μm cutoff at 35K are the highest reported at this very long wavelength. A simple defect model applied to the area
dependence of RoA at 40K implied a defect areal density of 3×104 cm−2 and a defect impedance of 3×106 ohm. 相似文献
10.
J. -O. Ndap C. I. Rablau K. Morrow O. O. Adetunji V. A. Johnson K. Chattopadhyay R. H. Page A. Burger 《Journal of Electronic Materials》2002,31(7):802-805
The maximum optical-absorption cross section of Cr2+ ions was evaluated from near-infrared (NIR) absorption spectroscopy and direct measurements of the chromium concentration
in Cr2+:CdSe crystals. The emission lifetime of the excited state, 5E, of Cr2+ was measured as a function of Cr2+ concentration in the 2×1017 −2×1018 ions/cm3 range and as a function of temperature from 77–300 K. Lifetime values were as high as ∼6 μs in the 77–250 K range and decreased
to ∼4 μs at 300 K because of nonradiative decays. Assuming that most of the Cr dopant is in the Cr2+ state, an optical-absorption cross section σa of (1.94±0.56) × 10−18 cm2 was calculated. Implications for laser performance are discussed. 相似文献
11.
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
12.
J. Antoszewski C. A. Musca J. M. Dell L. Faraone 《Journal of Electronic Materials》2000,29(6):837-840
This paper presents transport measurements on both vacancy doped and gold doped Hg0.7Cd0.3Te p-type epilayers grown by liquid phase epitaxy (LPE), with NA=2×1016 cm−3, in which a thin 2 μm surface layer has been converted to n-type by a short reactive ion etching (RIE) process. Hall and
resistivity measurements were performed on the n-on-p structures in van der Pauw configuration for the temperature range from
30 K to 400 K and magnetic field range up to 12 T. The experimental Hall coefficient and resistivity data has been analyzed
using the quantitative mobility spectrum analysis procedure to extract the transport properties of each individual carrier
contributing to the total conduction process. In both samples three distinct carrier species have been identified. For 77
K, the individual carrier species exhibited the following properties for the vacancy and Au-doped samples, respectively, holes
associated with the unconverted p-type epilayer with p ≈ 2 × 1016 cm−3, μ ≈ 350 cm2V−1s−1, and p ≈ 6 × 1015 cm−3, μ ≈ 400 cm2V−1s−1; bulk electrons associated with the RIE converted region with n ≈ 3 × 1015cm−3, μ ≈ 4 × 104 cm2V−1s−1, and n ≈ 1.5 × 1015 cm−3, μ ≈ 6 × 104 cm2V−1s−1; and surface electrons (2D concentration) n ≈ 9 × 1012 cm−2 and n ≈ 1 × 1013 cm−2, with mobility in the range 1.5 × 103 cm2V−1s−1 to 1.5 × 104 cm2V−1s−1 in both samples. The high mobility of bulk electrons in the RIE converted n-layer indicates that a diffusion process rather
than damage induced conversion is responsible for the p-to-n conversion deep in the bulk. On the other hand, these results
indicate that the surface electron mobility is affected by RIE induced damage in a very thin layer at the HgCdTe surface. 相似文献
13.
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
14.
A. I. D’Souza J. Bajaj R. E. De Wames D. D. Edwall P. S. Wijewarnasuriya N. Nayar 《Journal of Electronic Materials》1998,27(6):727-732
Mid wavelength infrared p-on-n double layer planar heterostructure (DLPH) photodiodes have been fabricated in HgCdTe double
layers grown in situ by liquid phase epitaxy (LPE), on CdZnTe and for the first time on CdTe/sapphire (PACE-1). Characterization of these devices
shed light on the nature of the material limits on device performance for devices performing near theoretical limits. LPE
double layers on CdZnTe and on PACE-1 substrates were grown in a horizontal slider furnace. All the photodiodes are p-on-n
heterostructures with indium as the n-type dopant and arsenic the p-type dopant. Incorporation of arsenic is via implantation
followed by an annealing step that was the same for all the devices fabricated. The devices are passivated with MBE CdTe.
Photodiodes have been characterized as a function of temperature. R0Aimp values obtained between 300 and 78K are comparable for the two substrates and are approximately a factor of five below theoretical
values calculated from measured material parameters. The data, for the PACE-1 substrate, indicates diffusion limited performance
down to 110K. Area dependence gives further indications as to the origin of diffusion currents. Comparable R0Aimp for various diode sizes indicates a p-side origin. R0A and optical characteristics for the photodiodes grown on lattice-matched CdZnTe substrates and lattice mismatched PACE-1
are comparable. Howover, differences were observed in the noise characteristics of the photodiodes. Noise was measured on
50 × 50 μm devices held under a 100 mV reverse bias. At 110K, noise spectrum for devices from the two substrates is in the
low 10−15 A/Hz1/2 range. This value reflects the Johnson noise of the room temperature 1010 Ω feedback resistor in the current amplifier that limits the minimum measurable noise. Noise at 1 Hz, −100 mV and 120K for
the 4.95 μm PACE-1 devices is in the 1–2 × 10−14 A/Hz1/2, a factor of 5–10 lower than previously grown typical PACE-1 n+-on-p layers. Noise at 120K for the 4.60 μm PACE-1 and LPE on CdZnTe was again below the measurement technique limit. Greatest
distinction in the noise characteristics for the different substrates was observed at 163K. No excess low frequency noise
was observed for devices fabricated on layers grown by LPE on lattice-matched CdZnTe substrates. Photodiode noise measured
at 1Hz, −100 mV and 163K in the 4.60 μm PACE-1 layer is in the 1–2×10−13 A/Hz1/2, again a factor of 5–10 lower than previously grown PACE-1 n+-on-p layers. More variation in noise (4×10−13−2×10−12 A/Hz1/2) was observed for devices in the 4.95 μm PACE-1 layer. DLPH devices fabricated in HgCdTe layers grown by LPE on lattice-matched
CdZnTe and on lattice-mismatched PACE-1 have comparable R0A and quantum efficiency values. The distinguishing feature is that the noise is greater for devices fabricated in the layer
grown on lattice mismatched substrates, suggesting dislocations inherent in lattice mismatched material affects excess low
frequency noise but not zero bias impedance. 相似文献
15.
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
16.
Polymers such as polyimides and photoresists, commonly used in semiconductor processing, have been investigated as high resolution
masks for ion implantation. Thin films consisting of these materials were subjected to various implant doses of H+, Ne+ and Ar+ ions and the post implantation surface morphologies investigated. Polyimides maintained their integrity under severe H+ and Ne+ implant doses as high as 2.4 × 1016 cm−2 and 1.0 × 1016 cm−2, respectively, whereas photoresists began to degrade at implant doses of 9.6 × 1015 cm−2 and 1.9 × 1015 cm−2, respectively. When polyimide was H+ implanted with doses up to 1016 cm−2 its dielectric constant and breakdown strength remained unchanged at 3.5 and 150 V/μm, respectively. However, a gradual increase
in the dielectric constant was observed for doses above this level. It was also observed that under the influence of H+ implants with beam current densities exceeding 10−7 A-cm−2 a hardening of the polyimide occurs, resulting in reduction of the etching rate in an O2 plasma. The stopping powers of various polymers for H+ implants have been measured. The results show that the experimental energy loss rate for protons in these materials lies
between 75–100 keV/μm. 相似文献
17.
Transformation of luminescence centers in CVD ZnS films subjected to a high hydrostatic pressure 总被引:8,自引:0,他引:8
N. K. Morozova I. A. Karetnikov V. G. Plotnichenko E. M. Gavrishchuk É. V. Yashina V. B. Ikonnikov 《Semiconductors》2004,38(1):36-41
The cathodoluminescence and optical-transmission spectra of ZnS were analyzed to study the effect of a high hydrostatic gas
pressure (1500 atm at 1000°C) on the equilibrium between intrinsic point defects in zinc sulfide grown by chemical vapor deposition
(CVD) with an excess of zinc. The cathodoluminescence spectra were measured at 80–300 K and excitation levels of 1022 and 1026 cm−3 s−1; the optical-transmission spectra were measured at 300 K in the wavelength range 4–12 μm. It is found that exposure to a
high hydrostatic gas pressure transforms the self-activated emission in the cathodoluminescence spectrum: (i) a new short-wave-length
band appears at 415 nm with its intensity increasing by one to three orders of magnitude; and (ii) the long-wavelength band
that peaks at 445 nm and is observed in as-grown crystals becomes quenched. Simultaneously, the cathodoluminescence band peaked
at 850 nm and related to vacancies V
S is no longer observed after high-pressure treatment. These effects are attributed to a partial escape of excess zinc (Zni) from crystals and additional incorporation of oxygen into lattice sites (OS). A doublet band I
1, which peaked at ∼331–332 nm at 80 K and at ∼342–343 nm at 300 K and is related to excitons bound to acceptor levels of oxygen
centers, was observed. This band is found to be dominant in the cathodoluminescence spectrum at an excitation level of 1026 cm−3 s−1. Traces of the ZnO phase are apparent after the high-pressure treatment in both the cathodolumi-nescence spectra (the bands
at 730 and 370 nm) and the transmission spectra (narrow bands in the region of 6–7 μm).
__________
Translated from Fizika i Tekhnika Poluprovodnikov, Vol. 38, No. 1, 2004, pp. 39–43.
Original Russian Text Copyright ? 2004 by Morozova, Karetnikov, Plotnichenko, Gavrishchuk, Yashina, Ikonnikov. 相似文献
18.
D. Chandra H. D. Shih F. Aqariden R. Dat S. Gutzler M. J. Bevan T. Orent 《Journal of Electronic Materials》1998,27(6):640-647
Void defects were demonstrated to form away from the substrate-epifilm interface during the molecular beam epitaxial growth
of mercury cadmium telluride on cadmium zinc telluride substrates. These were smaller in size compared to voids which nucleated
at the substrate-epifilm interface, which were also observed. Observations of void nucleation away from the substrate-epifilm
interface were related to the respective growth regimes active at the time of the void nucleation. Once nucleated, voids replicated
all the way to the surface even if the flux ratios were modified to prevent additional nucleation of voids. For a significant
number of films, void defects were observed co-located with hillocks. These voids were usually smaller than 1 μm and appeared
almost indistinguishable from unaccompanied simple voids. However, these void-hillock complexes displayed a nest of dislocation
etch pits around these defects upon dislocation etching, whereas unaccompanied voids did not. The nests could extend as much
as 25 μm from the individual void-hillock complex. The density of dislocations within the nest exceeded 5×106 cm−2, whereas the dislocation density outside of the nest could decrease to <2×105 cm−2. The void-hillock complexes formed due to fluctuations in growth parameters. Elimination of these fluctuations drastically
decreased the concentrations of these defects. 相似文献
19.
C. Blaauw R. A. Bruce C. J. Miner A. J. Howard B. Emmerstorfer A. J. Springthorpe 《Journal of Electronic Materials》1989,18(5):567-572
The use of bis(methylcyclopentadienyl)magnesium (MCp2Mg) as ap-dopant source for MOCVD-grown InP has been investigated. The Mg incorporation was nonlinear. The relationship between the
H2 flow through the MCp2Mg bubbler and the Mg concentra-tion in the epilayers suggested that when [Mg] <20 ppb in the reactor it was mostly depleted
from the gas mixture, probably by means of reaction with O2 or H2O, but at higher concentrations a large fraction of the Mg diffusing to the epilayers was incor-porated. For concentrations
>1019 cms-3 the layer morphology deteriorated and stacking faults were observed by TEM, at a density greater than 109 cms−2. Significant diffusion of Mg into the substrates during the growth was observed, with diffusion depths up to 0.1 μm at a
concentration of 1019 cms−3 in S-doped, and up to 32 μm at 1017 cms-3 in Fe-doped substrates. These concentrations correspond to the S and Fe doping level in those substrates, and the results
are explained in terms of the formation of a complex between the S or Fe dopants and the diffusing Mg, which immobilizes the
latter species. At [Mg] >1018 cms−3, the net hole concentration, measured by means of electrochemical C-V pro-filing, decreases with increasing [Mg], indicating
significant self compensation. Com-pensation at high [Mg] was also suggested by the effect of excitation power density on
the peak shift of the donor to acceptor transition observed during photoluminescence measurements at 7 K. 相似文献
20.
A. I. D’Souza M. G. Stapelbroek P. N. Dolan P. S. Wijewarnasuriya R. E. DeWames D. S. Smith J. C. Ehlert 《Journal of Electronic Materials》2003,32(7):633-638
The 1/f noise in photovoltaic (PV) molecular-beam epitaxy (MBE)-grown Hg1−xCdxTe double-layer planar heterostructure (DLPH) large-area detectors is a critical noise component with the potential to limit
sensitivity of the cross-track infrared sounder (CrIS) instrument. Therefore, an understanding of the origins and mechanisms
of noise currents in these PV detectors is of great importance. Excess low-frequency noise has been measured on a number of
1000-μm-diameter active-area detectors of varying “quality” (i.e., having a wide range of I-V characteristics at 78 K). The
1/f noise was measured as a function of cut-off wavelength under illuminated conditions. For short-wave infrared (SWIR) detectors
at 98 K, minimal 1/f noise was measured when the total current was dominated by diffusion with white noise spectral density
in the mid-10−15A/Hz1/2 range. For SWIR detectors dominated by other than diffusion current, the ratio, α, of the noise current in unit bandwidth
in(f = 1 Hz, Vd = −60 mV, and Δf = 1 Hz) to dark current Id(Vd = −60 mV) was αSW-d = in/Id ∼ 1 × 10−3. The SWIR detectors measured at 0 mV under illuminated conditions had median αSW-P = in/Iph ∼ 7 × 10−6. For mid-wave infrared (MWIR) detectors, αMW-d = in/Id ∼ 2 × 10−4, due to tunneling current contributions to the 1/f noise. Measurements on forty-nine 1000-μm-diameter MWIR detectors under
illuminated conditions at 98 K and −60 mV bias resulted in αMW-P = in/Iph = 4.16 ± 1.69 × 10−6. A significant point to note is that the photo-induced noise spectra are nearly identical at 0 mV and 100 mV reverse bias,
with a noise-current-to-photocurrent ratio, αMW-P, in the mid 10−6 range. For long-wave infrared (LWIR) detectors measured at 78 K, the ratio, αLW-d = in/Id ∼ 6 × 10−6, for the best performers. The majority of the LWIR detectors exhibited αLW-d on the order of 2 × 10−5. The photo-induced 1/f noise had αLW-P = in/Iph ∼ 5 × 10−6. The value of the noise-current-to-dark-current ratio, α appears to increase with increasing bandgap. It is not clear if
this is due to different current mechanisms impacting 1/f noise performance. Measurements on detectors of different bandgaps
are needed at temperatures where diffusion current is the dominant current. Excess low-frequency noise measurements made as
a function of detector reverse bias indicate 1/f noise may result primarily from the dominant current mechanism at each particular
bias. The 1/f noise was not a direct function of the applied bias. 相似文献