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1.
T. S. Lee J. Garland C. H. Grein M. Sumstine A. Jandeska Y. Selamet S. Sivananthan 《Journal of Electronic Materials》2000,29(6):869-872
The behavior of arsenic for p-type doping of MBE HgCdTe layers has been studied for various annealing temperatures and arsenic
doping concentrations. We have demonstrated that arsenic is in-situ incorporated into HgCdTe layers during MBE growth. The
carrier concentration has been measured by the Van der Pauw technique, and the total arsenic concentration has been determined
by secondary ion mass spectroscopy. After annealing at 250°C under an Hg over pressure, As-doped HgCdTe layers show highly
compensated n-type properties and the carrier concentration is approximately constant (∼mid 1015 cm−3) until the total arsenic concentration in the HgCdTe layers approach mid 1017 cm−3. The source of n-type behavior does not appear to be associated with arsenic dopants, such as arsenic atoms occupying Hg
vacancy sites, but rather unidentified structural defects acting as donors. When the total arsenic concentration is above
mid 1017 cm−3, the carrier concentration shows a dependence on the arsenic concentration while remaining n-type. We conjecture that the
increase in n-type behavior may be due to donor arsenic tetramers or donor tetramer clusters. Above a total arsenic concentration
of 1∼2×1018 cm−3, after annealing at 300°C, the arsenic acceptor activation ratio rapidly decreases below 100% with increasing arsenic concentration
and is smaller than that after annealing at 450°C. The electrically inactive arsenic is inferred to be in the form of neutral
arsenic tetramer clusters incorporated during the MBE growth. Annealing at 450°C appears to supply enough thermal energy to
break some of the bonds of neutral arsenic tetramer clusters so that the separated arsenic atoms could occupy Te sites and
behave as acceptors. However, the number of arsenic atoms on Te sites is saturated at ∼2×1018 cm−3, possibly due to a limitation of its solid solubility in HgCdTe. 相似文献
2.
H. Nishino S. Murakami T. Saito Y. Nishijima H. Takigawa 《Journal of Electronic Materials》1995,24(5):533-537
We studied dislocation etch pit density (EPD) profiles in HgCdTe(lOO) layers grown on GaAs(lOO) by metalorganic chemical vapor
deposition. Dislocation profiles in HgCdTe(lll)B and HgCdTe(lOO) layers differ as follows: Misfit dislocations in HgCdTe(lll)B
layers are concentrated near the HgCdTe/CdTe interfaces because of slip planes parallel to the interfaces. Away from the HgCdTe/CdTe
interface, the HgCdTe(111)B dislocation density remains almost constant. In HgCdTe(lOO) layers, however, the dislocations
propagate monotonically to the surface and the dislocation density decreases gradually as dislocations are incorporated with
increasing HgCdTe(lOO) layer thicknesses. The dislocation reduction was small in HgCdTe(lOO) layers more than 10 μm from the
HgCdTe/CdTe interface. The CdTe(lOO) buffer thickness and dislocation density were similarly related. Since dislocations glide
to accommodate the lattice distortion and this movement increases the probability of dislocation incorporation, incorporation
proceeds in limited regions from each interface where the lattice distortion and strain are sufficient. We obtained the minimum
EPD in HgCdTe(100) of 1 to 3 x 106 cm-2 by growing both the epitaxial layers more than 8 μm thick. 相似文献
3.
C. A. Musca J. Antoszewski J. M. Dell L. Faraone S. Terterian 《Journal of Electronic Materials》2003,32(7):622-626
Planar p-on-n HgCdTe heterojunction photodiodes have been fabricated using a plasma-induced type conversion process for device
junction isolation. The technique is presented as a fully planar alternative technology to the commonly used mesa isolation
structure. The starting material consisted of an indium-doped n-type mid-wavelength infrared (MWIR) HgCdTe absorbing layer
that was capped by a 1-μm-thick wider bandgap arsenic-doped p-type layer. Junction-isolated p-on-n diodes were formed by selectively
p-to-n type converting the p-type cap layer using a plasma process. Photodiode dark current-voltage measurements were performed
as a function of temperature, along with noise and responsivity. The devices have cut-off wavelengths between 4.8 μm and 5.0
μm, exhibit diffusion-limited dark currents down to 145 K, give R0A values greater than 1 × 107Ω·cm2 at 80 K and greater than 1 × 105Ω·cm2 at 120 K, and have negligible 1/f noise current at zero applied bias. 相似文献
4.
J. P. Tower S. P. Tobin P. W. Norton A. B. Bollong A. Socha J. H. Tregilgas C. K. Ard H. F. Arlinghaus 《Journal of Electronic Materials》1996,25(8):1183-1187
Recent improvements in sputter initiated resonance ionization spectroscopy (SIRIS) have now made it possible to measure copper
in HgCdTe films into the low 1013 cm−3 range. We have used this technique to show that copper is responsible for type conversion in n-type HgCdTe films. Good n-type
LPE films were found to have less than 1 x 1014 cm−3 copper, while converted p-type samples were found to have copper concentrations approximately equal to the hole concentrations.
Some compensated n-type samples with low mobilities have copper concentrations too low to account for the amount of compensation
and the presence of a deep acceptor level is suggested. In order to study diffusion of copper from substrates into LPE layers,
a CdTe boule was grown intentionally spiked with copper at approximately 3 x 1016 cm−3. Annealing HgCdTe films at 360°C was found to greatly increase the amount of copper that diffuses out of the substrates and
a substrate screening technique was developed based on this phenomenon. SIRIS depth profiles showed much greater copper in
HgCdTe films than in the substrates, indicating that copper is preferentially attracted to HgCdTe over Cd(Zn)Te. SIRIS spatial
mapping showed that copper is concentrated in substrate tellurium inclusions 5–25 times greater than in the surrounding CdZnTe
matrix. 相似文献
5.
R. Korenstein P. H. Hallock D. L. Lee E. Sullivan R. W. Gedridge K. T. Higa 《Journal of Electronic Materials》1993,22(8):853-857
A new indium source, triisopropylindium, was used to dope HgCdTe layers grown by metalorganic chemical vapor deposition n-type
with carrier concentrations, nH, in the range between low 1015 and low 1017 cm−3 at 77K. The reproducibility of carrier concentration was found to be excellent for nH<3×1015 cm−3. High electron mobilities and minority carrier lifetime comparable to published values indicate that indium doping produces
high quality n-type HgCdTe material. State-of the-art photodiodes were obtained by growing a p-type HgCdTe layer by liquid
phase epitaxy on an indium doped layer. In addition, and adduct compound formed between diisopropyltellurium (DIPTe) and triisopropylindium
(TIPIn): DIPTe·InTIP, was also found to be a viable n-type dopant for HgCdTe especially at concentrations in the low 1015 cm−3 or less. 相似文献
6.
R. D. Rajavel D. M. Jamba J. E. Jensen O. K. Wu C. Le Beau J. A. Wilson E. Patten K. Kosai J. Johnson J. Rosbeck P. Goetz S. M. Johnson 《Journal of Electronic Materials》1997,26(6):476-481
The first report of molecular beam epitaxial growth and performance of HgCdTe two-color detectors for the simultaneous detection
of radiation at 4.1 and 4.5 μm is presented. In-situ doped devices with the n-p-n architecture were grown by molecular beam
epitaxy on (211)B CdZnTe substrates. Representative structures exhibited x-ray rocking curves with full width at half-maxima
of 40–60 arcs. The typical near surface etch pit density in these structures were 4−7 × 106 cm−2. The devices were processed as mesa diodes and electrical contacts were made to the two n-type layers and the p-type layer
to facilitate simultaneous operation of the two p-n junctions. The spectral response characteristics of the devices were characterized
by sharp turn-on and turn-off for both bands, with R0A values >5 × 105 ωcm2 at 77K. The detectors exhibited quantum efficiencies >70% in both bands. 相似文献
7.
L. H. Zhang S. D. Pearson W. Tong B. K. Wagner J. D. Benson C. J. Summers 《Journal of Electronic Materials》1998,27(6):600-604
This paper presents a study of both as-grown and annealed p-type Hg1−xCdxTe layers that were doped using a cadmium arsenide source. It is shown that by using a metalorganic molecular beam epitaxy
system stable and reproducible p-type HgCdTe:As layers were obtained through direct homogeneous doping. The hole concentrations
in the as-grown and annealed samples were 8 × 1016 to 3 × 1017 cm−3 with mobilities of 120∼300 cm2/V-s. The as-grown HgCdTe:As layers had very good crystalline quality with double crystal x-ray rocking curve line-widths
ranging from 27 to 42 arc sec. Experimental data demonstrated a strong correlation of hole concentration and mobility with
the surface morphology and crystalline quality as a function of Hg flux. The optimum growth window was defined by a narrow
range of Hg flux values that gave a smooth film with fewer voids, and higher hole concentrations and mobilities than were
obtained at lower or higher Hg fluxes. This correlation between the growth window defined by the surface morphology and the
dopant behavior was very important for the successful growth of p-type As-doped HgCdTe materials. 相似文献
8.
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
9.
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
10.
E. P. G. Smith G. M. Venzor M. D. Newton M. V. Liguori J. K. Gleason R. E. Bornfreund S. M. Johnson J. D. Benson A. J. Stoltz J. B. Varesi J. H. Dinan W. A. Radford 《Journal of Electronic Materials》2005,34(6):746-753
Inductively coupled plasma (ICP) using hydrogen-based gas chemistry has been developed to meet requirements for deep HgCdTe
mesa etching and shallow CdTe passivation etching in large format HgCdTe infrared focal plane array (FPA) fabrication. Large
format 2048×2048, 20-μm unit-cell short wavelength infrared (SWIR) and 2560×512, 25-μm unit-cell midwavelength infrared (MWIR)
double-layer heterojunction (DLHJ) p-on-n HgCdTe FPAs fabricated using ICP processing exhibit >99% pixel operability. The
HgCdTe FPAs are grown by molecular beam epitaxy (MBE) on Si substrates with suitable buffer layers. Midwavelength infrared
detectors fabricated from 4-in. MBE-grown HgCdTe/Si substrates using ICP for mesa delineation and CdTe passivation etching
demonstrate measured spectral characteristics, RoA product, and quantum efficiency comparable to detectors fabricated using
wet chemical processes. Mechanical samples prepared to examine physical characteristics of ICP reveal plasma with high energy
and low ion angle distribution, which is necessary for fine definition, high-aspect ratio mesa etching with accurate replication
of photolithographic mask dimensions. 相似文献
11.
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
12.
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
13.
Dong H. K. Li N. Y. Tu C. W. Geva M. Mitchel W. C. 《Journal of Electronic Materials》1995,24(2):69-74
The growth of GaAs by chemical beam epitaxy using triethylgallium and trisdimethylaminoarsenic has been studied. Reflection
high-energy electron diffraction (RHEED) measurements were used to investigate the growth behavior of GaAs over a wide temperature
range of 300–550°C. Both group III- and group Vinduced RHEED intensity oscillations were observed, and actual V/III incorporation
ratios on the substrate surface were established. Thick GaAs epitaxial layers (2–3 μm) were grown at different substrate temperatures
and V/III ratios, and were characterized by the standard van der Pauw-Hall effect measurement and secondary ion mass spectroscopy
analysis. The samples grown at substrate temperatures above 490°C showed n-type conduction, while those grown at substrate
temperatures below 480°C showed p-type conduction. At a substrate temperature between 490 and 510°C and a V/III ratio of about
1.6, the unintentional doping concentration is n ∼2 × 1015 cm−3 with an electron mobility of 5700 cm2/V·s at 300K and 40000 cm2/V·s at 77K. 相似文献
14.
T. J. De Lyon J. E. Jensen I. Kasai G. M. Venzor K. Kosai J. B. de Bruin W. L. Ahlgren 《Journal of Electronic Materials》2002,31(3):220-226
Results are reported on the molecular-beam epitaxial (MBE) growth and electrical performance of HgCdTe midwave-infrared (MWIR)
detector structures. These devices are designed for operation in the 140–160 K temperature range with cutoff wavelengths ranging
from 3.4–3.8 μm at 140 K. Epitaxial structures, grown at 185°C on (211)B-oriented CdZnTe substrates, consisting of either
conventional two-layer P-n configurations or three-layer P-n-N configurations, were designed to examine the impact of device
performance on variation of the n-type base layer (absorber) thickness and the inclusion or omission of an underlying wide-bandgap
buffer layer. Devices were grown with absorber thicknesses of 3 μm, 5 μm, and 7 μm to examine the tradeoff between the spectral
response characteristic and the reverse-bias electrical performance. In addition, 5-μm-thick, wide-bandgap HgCdTe buffer layers,
whose CdTe mole fraction was approximately 0.1 larger than the absorber layer, were introduced into several device structures
to study the effect of isolating the device absorbing layer from the substrate/growth initiation interface. The MBE-grown
epitaxial wafers were processed into passivated, mesa-type, discrete device structures and diode mini arrays, which were tested
for temperature-dependent R0A product, quantum efficiency, spectral response, and the I-V characteristic at temperatures close to 140 K. External quantum
efficiencies of 75–79% were obtained with lateral optical-collection lengths of 7 μm. Analysis of the temperature dependence
of the diode R0A product indicates that the device impedance is limited by the diffusion current at temperatures above 140 K with typical
R0A values of 2×106 Ω cm2 for a detector cutoff of 3.8 μm at 140 K. An alloy composition anomaly at the absorbing-layer/buffer-layer interface is believed
to limit the observed R0A products to values approximately one order of magnitude below the theoretical limit projected for radiatively limited carrier
lifetime. Device electrical performance was observed to be improved through incorporation of a wide-bandgap buffer layer and
through reduction of the absorbing layer thickness. An optimum spectral response characteristic was observed for device structures
with 5-μm-thick absorbing layers. 相似文献
15.
V. Kumar R. Pal P. K. Chaudhury B. L. Sharma V. Gopal 《Journal of Electronic Materials》2005,34(9):1225-1229
Passivant-Hg1−xCdxTe interface has been studied for the CdTe and anodic oxide (AO) passivants. The former passivation process yields five times
lower surface recombination velocity than the latter process. Temperature dependence of surface recombination velocity of
the CdTe/n-HgCdTe and AO/n-HgCdTe interface is analyzed. Activation energy of the surface traps for CdTe and AO-passivated
wafers are estimated to be in the range of 7–10 meV. These levels are understood to be arising from Hg vacancies at the HgCdTe
surface. Fixed charge density for CdTe/n-HgCdTe interface measured by CV technique is 5×1010 cm−2, which is comparable to the epitaxially grown CdTe films. An order of magnitude improvement in responsivity and a factor
of 4 increase in specific detectivity (D*) is achieved by CdTe passivation over AO passivation. This study has been conducted
on photoconductive detectors to qualify the CdTe passivation process, with an ultimate aim to use it for the passivation of
p-on-n and n-on-p HgCdTe photodiodes. 相似文献
16.
P. Mitra T. R. Schimert F. C. Case R. Starr M. H. Weiler M. Kestigian M. B. Reine 《Journal of Electronic Materials》1995,24(5):661-668
Metalorganic chemical vapor depositon (MOCVD) in situ growth of p-on-n junctions for long wavelength infrared (LWIR) and medium
wavelength infrared (MWIR) photodiodes is reported. The interdiffused multilayer process was used for the growth of the HgCdTe
junctions on CdTe and CdZnTe substrates. The n-type region was grown undoped while the p-type layer was arsenic doped using
tertiarybutylarsine. Following a low temperature anneal in Hg vapor, carrier densities of (0.2-2) x 1015 cm3 and mobilities of (0.7-1.2) x 105 cm2/V-s were obtained for n-type LWIR (x ~ 0.22) layers at 80K. Carrier lifetimes of these layers at 80 K are ~l-2 μs. For the
p-type region arsenic doping was controlled in the range of (1-20) x 1016 cm-3. Arsenic doping levels in the junctions were determined by calibrated secondary ion mass spectroscopy depth profile measurements.
Composition and doping of the p-on-n heterojunctions could be independently controlled so that the electrical junction could
be located deeper than the change in the composition. The graded composition region between the narrow and wide (x = 0.28-0.30)
bandgap regions are 1–2 μm depending on the growth temperature. Backside-illuminated variable-area circular mesa photodiode
arrays were fabricated on the grown junctions as well as on ion implanted n-on-p MWIR junctions. The spectral responses are
classical in shape. Quantum efficiencies at 80K are 42–77% for devices without anti-reflection coating and with cutoff wavelengths
of 4.8–11.0 μm. Quantum efficiencies are independent of reverse bias voltage and do not decrease strongly at lower temperatures
indicating that valence band barrier effects are not present. 80K RoA of 15.9 Ω-cm2 was obtained for an array with 11.0 μm cutoff. Detailed measurements of the characteristics of the MOCVD in situ grown and
implanted photodiodes are reported. 相似文献
17.
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
18.
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
19.
E. Belas V. V. Bogoboyashchyy R. Grill I. I. Izhnin A. P. Vlasov V. A. Yudenkov 《Journal of Electronic Materials》2003,32(7):698-702
Time relaxation of the electrical conductivity σ(77 K) and Hall coefficient RH(77 K) of the n-type layer created by ion milling is investigated in Hg vacancy-doped, As-doped, and In-predoped p-type, and
In-doped n-type Hg1−xCdxTe (0.2 < x < 0.22) samples. We show that the n-type layer is formed, and the temperature-activated relaxation occurs in all
cases. The annealing at 75°C results in a gradual degradation of the converted n-type layer and a back n-to-p conversion within
8 days. The existence of a high-conducting, surface-damaged region with a high-electron density (∼1018 cm−3) and a low mobility (∼103 cm2/Vs) is confirmed, and its influence on the relaxation is studied. 相似文献
20.
P. Mitra F. C. Case H. L. Glass V. M. Speziale J. P. Flint S. P. Tobin P. W. Norton 《Journal of Electronic Materials》2001,30(6):779-784
We report the growth of HgCdTe on (552)B CdZnTe by metalorganic vapor phase epitaxy (MOVPE). The (552) plane is obtained by
180 rotation of the (211) plane about the [111] twist axis. Both are 19.47 degrees from (111), but in opposite directions.
HgCdTe grown on the (552)B-oriented CdZnTe has a growth rate similar to the (211)B, but the surface morphology is very different.
The (552)B films exhibit no void defects, but do exhibit ∼40 μm size hillocks at densities of 10–50 cm−2. The hillocks, however, are significantly flatter and shorter than those observed on (100) metalorganic vapor phase epitaxy
(MOVPE) HgCdTe films. For a 12–14 μm thick film the height of the highest point on the hillock is less than 0.75 μm. No twinning
was observed by back-reflection Laue x-ray diffraction for (552)B HgCdTe films and the x-ray double crystal rocking curve
widths are comparable to those obtained on (211)B films grown side-by-side and with similar alloy composition. Etch pit density
(EPD) measurements show EPD values in the range of (0.6–5)×105 cm−2, again very similar to those currently observed in (211)B MOVPE HgCdTe. The transport properties and ease of dopant incorporation
and activation are all comparable to those obtained in (211)B HgCdTe. Mid-wave infrared (MWIR) photodiode detector arrays
were fabricated on (552)B HgCdTe films grown in the P-n-N device configuration (upper case denotes layers with wider bandgaps).
Radiometric characterization at T=120–160 K show that the detectors have classical spectral response with a cutoff wavelength
of 5.22 μm at 120 K, quantum efficiency ∼78%, and diffusion current is the dominant dark current mechanism near zero bias
voltage. Overall, the results suggest that (552)B may be the preferred orientation for MOVPE growth of HgCdTe on CdZnTe to
achieve improved operability in focal plane arrays. 相似文献