共查询到20条相似文献,搜索用时 47 毫秒
1.
S. Terterian M. Chu S. Mesropian H. Gurgenian J. D. Benson J. H. Dinan 《Journal of Electronic Materials》2004,33(6):615-620
Two-dimensional near-infrared (NIR) and short-wave infrared (SWIR) HgCdTe arrays have been produced using planar ion-implantation
isolated heterojunction (PI3H) device technology. This paper is an extension of an earlier study in which focal plane arrays
(FPAs) were fabricated based on heterojunction-mesa and ion-implanted planar device structures. The PI3H device structure
is pursued in order to verify whether it can encompass both the superb multilayer characteristics of heterojunction detectors
as well as the planar integrity of ion-implanted devices. The PI3H devices are characterized, and R0A measurements are carried out at different temperatures and compared to those obtained from heterojunction-mesa and ion-implanted
device structures. Data shows the PI3H devices to be superior to both heterojunctionmesa and ion-implanted detectors at temperatures
between 130 K and 300 K. Performance characteristics of the thermoelectric (TE) cooled SWIR FPAs with 320 × 256 format, as
well as NIR FPAs with 640×512 format based on the PI3H device structure are also discussed. 相似文献
2.
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
3.
L. O. Bubulac W. E. Tennant J. G. Pasko L. J. Kozlowski M. Zandian M. E. Motamedi R. E. De Wames J. Bajaj N. Nayar W. V. McLevige N. S. Gluck R. Melendes D. E. Cooper D. D. Edwall J. M. Arias R. Hall A. I. D’souza 《Journal of Electronic Materials》1997,26(6):649-655
Short wave infrared (SWIR) devices have been fabricated using Rockwell’s double layer planar heterostructure (DLPH) architecture
with arsenic-ion implanted junctions. Molecular beam epitaxially grown HgCdTe/CdZnTe multilayer structures allowed the thin,
tailored device geometries (typical active layer thickness was ∼3.5 μm and cap layer thickness was ∼0.4 μm) to be grown. A
planar-mesa geometry that preserved the passivation advantages of the DLPH structure with enhanced optical collection improved
the performance. Test detectors showed Band 7 detectors performing near the radiative limit (∼3-5X below theory). Band 5 detector
performance was ∼4-50X lower than radiative limited performance, apparently due to Shockley-Hall-Read recombination. We have
fabricated SWIR HgCdTe 256 × 12 × 2 arrays of 45 um × 45 μm detector on 45 μm × 60 μm centers and with cutoff wavelength which
allows coverage of the Landsat Band 5 (1.5−1.75 μm) and Landsat Band 7 (2.08−2.35 μm) spectral regions. The hybridizable arrays
have four subarrays, each having a different detector architecture. One of the Band 7 hybrids has demonstrated performance
approaching the radiative theoretical limit for temperatures from 250 to 295K, consistent with test results. D* performance
at 250K of the best subarray was high, with an operability of ∼99% at 1012 cm Hz1/2/W at a few mV bias. We have observed 1/f noise below 8E-17 AHz 1/2 at 1 Hz. Also for Band 7 test structures, Ge thin film diffractive microlenses fabricated directly on the back side of the
CdZnTe substrate showed the ability to increase the effective collection area of small (nominally <20 μm μm) planar-mesa diodes
to the microlens size of 48 urn. Using microlenses allows array performance to exceed 1-D theory up to a factor of 5. 相似文献
4.
L. A. Almeida M. Thomas W. Larsen K. Spariosu D. D. Edwall J. D. Benson W. Mason A. J. Stoltz J. H. Dinan 《Journal of Electronic Materials》2002,31(7):669-676
We report the development and fabrication of two-color mid-wavelength infrared (MWIR) and short-wavelength infrared (SWIR)
HgCdTe-based focalplane arrays (FPAs). The HgCdTe multilayers were deposited on bulk CdZnTe (ZnTe mole fraction ∼3%) using
molecular beam epitaxy (MBE). Accurate control of layer composition and growth rate was achieved using in-situ spectroscopic
ellipsometry (SE). Epilayers were evaluated using a variety of techniques to determine suitability for subsequent device processing.
These techniques included Fourier transform infrared (FTIR) spectroscopy, Hall measurement, secondary ion mass spectroscopy
(SIMS), defect-decoration etching, and Nomarski microscopy. The FTIR transmission measurements confirmed SE’s capability to
provide excellent compositional control with run-to-run x-value variations of ∼0.002. Nomarski micrographs of the as-grown
surfaces featured cross-hatch patterns resulting from the substrate/epilayer lattice mismatch as well as various surface defects
(voids and “microvoids”), whose densities ranged from 800–8,000 cm−2. A major source of these surface defects was substrate particulate contamination. Epilayers grown following efforts to reduce
these particulates exhibited significantly lower densities of surface defects from 800–1,700 cm−2. Dislocation densities, as revealed by a standard defect-decoration etch, were 2–20×105 cm−2, depending on substrate temperature during epitaxy. The FPAs (128×128) were fabricated from these epilayers. Preliminary
performance results will be presented. 相似文献
5.
Effect of dislocations on performance of LWIR HgCdTe photodiodes 总被引:2,自引:0,他引:2
The epitaxial growth of HgCdTe on alternative substrates has emerged as an enabling technology for the fabrication of large-area
infrared (IR) focal plane arrays (FPAs). One key technical issue is high dislocation densities in HgCdTe epilayers grown on
alternative substrates. This is particularly important with regards to the growth of HgCdTe on heteroepitaxial Si-based substrates,
which have a higher dislocation density than the bulk CdZnTe substrates typically used for epitaxial HgCdTe material growth.
In the paper a simple model of dislocations as cylindrical regions confined by surfaces with definite surface recombination
is proposed. Both radius of dislocations and its surface recombination velocity are determined by comparison of theoretical
predictions with carrier lifetime experimental data described by other authors. It is observed that the carrier lifetime depends
strongly on recombination velocity; whereas the dependence of the carrier lifetime on dislocation core radius is weaker. The
minority carrier lifetime is approximately inversely proportional to the dislocation density for densities higher than 105 cm−2. Below this value, the minority carrier lifetime does not change with dislocation density. The influence of dislocation density
on the R0A product of long wavelength infrared (LWIR) HgCdTe photodiodes is also discussed. It is also shown that parameters of dislocations
have a strong effect on the R0A product at temperature around 77 K in the range of dislocation density above 106 cm−2. The quantum efficiency is not a strong function of dislocation density. 相似文献
6.
MBE growth of HgCdTe on silicon substrates for large-area infrared focal plane arrays: A review of recent progress 总被引:3,自引:0,他引:3
T. J. de Lyon J. E. Jensen M. D. Gorwitz C. A. Cockrum S. M. Johnson G. M. Venzor 《Journal of Electronic Materials》1999,28(6):705-711
We review the rapid progress that has been made during the past three years in the heteroepitaxial growth of HgCdTe infrared
detector device structures on Si substrates by molecular-beam epitaxy. The evolution of this technology has enabled the fabrication
of high performance, large-area HgCdTe infrared focal-plane arrays on Si substrates. A key element of this heteroepitaxial
approach has been development of high quality CdTe buffer layers deposited on Si(112) substrates. We review the solutions
developed by several groups to address the difficulties associated with the CdTe/Si(112) heteroepitaxial system, including
control of crystallographic orientation and minimization of defects such as twins and threading dislocations. The material
quality of HgCdTe/Si and the performance of HgCdTe detector structures grown on CdTe/Si(112) composite substrates is reviewed.
Finally, we discuss some of the challenges related to composition uniformity and defect generation encountered with scaling
the MBE growth process for HgCdTe to large-area Si substrates. 相似文献
7.
G. Destefanis J. Baylet P. Ballet P. Castelein F. Rothan O. Gravrand J. Rothman J. P. Chamonal A. Million 《Journal of Electronic Materials》2007,36(8):1031-1044
In this paper we show the latest achievements of HgCdTe-based infrared bispectral focal plane arrays (FPAs) at LETI infrared
laboratory. We present and compare the two different pixel architectures that are studied now in our laboratory, named “NPN”
and “pseudo-planar”. With these two technologies, a wide range of system applications in dual-band detection can be covered.
Advantages of both architectures will be pointed out. We also review performances obtained with these different architectures.
The first one has been studied for several years in our laboratory, and we review results obtained on FPAs of size 256 × 256 pixels
on a 25 μm pitch, in the MWIR/MWIR (3 μm/5 μm) range. Very high noise equivalent temperature difference (NETD) operability is obtained, at 99.8% for the λc = 3 μm band and 98.7% for the λc = 5 μm band. The second one has been developed more recently, to address other applications that need temporal coherence as well
as spatial coherence. We show detailed performances measured on pseudo-planar type FPAs of size 256 × 256 pixels on a 30 μm pitch, in the MWIR/LWIR (5 μm/9 μm) range. The results are also very promising for these prototypes, with NETD as low as 15 mK for an integration time as short
as 1 ms, and good operability. The main manufacturing issues are also presented and discussed for both pixel architectures.
Challenging process steps are, firstly, molecular beam epitaxy (MBE) HgCdTe heterostructure growth, on large substrates (cadmium
zinc telluride) and heterosubstrates (germanium), and, secondly, detector array fabrication on a nonplanar surface. In particular,
trenches or hole etching steps, photolithography and hybridization are crucial to improve uniformity, number of defects and
performances. Some results of surface, structural and electrical characterizations are shown to illustrate these issues. On
the basis of these results, the short-term and long-term objectives and trends for our research and development are presented,
in terms of pixel pitch reduction, wavelengths, and dual-band FPA size. 相似文献
8.
J. Antoszewski K. J. Winchester A. J. Keating T. Nguyen K. K. M. B. D. Silva C. A. Musca J. M. Dell L. Faraone P. Mitra J. D. Beck M. R. Skokan J. E. Robinson 《Journal of Electronic Materials》2005,34(6):716-721
A monolithically integrated low-temperature micro-electro-mechanical systems (MEMS) and HgCdTe infrared (IR) detector technology
is introduced, implemented, and characterized. The ultimate aim of this project is to develop a MEMS-based optical filter,
integrated with an IR detector, that selects narrow wavelength bands within the short-wavelength IR (SWIR) region of the spectrum.
The entire fabrication process is compatible with two-dimensional IR focal plane array technology, and needs to be compatible
with a proposed electrically tunable MEMS filter based on a Fabry-Perot optical cavity. The fabricated device consists of
an HgCdTe SWIR photoconductor, distributed Bragg mirrors formed of Ge-SiO-Ge, a sacrificial spacer layer within the cavity,
and a silicon nitride membrane for structural support. Mirror stacks fabricated on silicon, identical to the structures that
will form the optical cavity, have been characterized to determine the optimum filter characteristics. The measured full-width
at half-maximum (FWHM) was 34 nm at the center wavelength of 1,780 nm with an extinction ratio of 36.6. Fully integrated filters
on HgCdTe photoconductors with a center wavelength of approximately 1,950 nm give a FWHM of approximately 100 nm, and a peak
responsivity of approximately 8×104 V/W. The experimental results are in good agreement with the optical model, which takes into account mirror reflectivity,
absorption within the cavity by the spacer material, and absorption by the silicon nitride support structure. 相似文献
9.
Analysis of crosstalk in HgCdTe p-on-n heterojunction photovoltaic infrared sensing arrays 总被引:1,自引:0,他引:1
C. A. Musca J. M. Dell L. Faraone J. Bajaj T. Pepper K. Spariosu J. Blackwell C. Bruce 《Journal of Electronic Materials》1999,28(6):617-623
In this paper, an experimental and theoretical study is carried out of crosstalk between nearest-neighbor devices within a
backside-illuminated linear HgCdTe photovoltaic infrared sensing array. The dominant form of crosstalk that occurs in high
performance photovoltaic arrays is associated with photogenerated minority carriers that diffuse laterally between adjacent
devices within the array. To measure crosstalk, a scanning laser microscope is used to obtain a spatial map of spot-scan photoresponse
at a temperature of 80K for individual p-on-n photovoltaic devices within the linear array. These experimental results are
compared to calculations performed on a commercial two-dimensional device simulation package. The crosstalk measurements and
calculations presented in this paper include results on mid-wavelength infrared planar device structures, as well as long-wavelength
infrared mesa-isolated devices, which give measured crosstalk values of 6.2 and 8.3%, respectively. The results indicate that
the device simulations are in good agreement with experimental results. Further simulations are carried out to determine the
sensitivity of crosstalk to various material and device parameters such as epitaxial layer thickness (7 to 25 μm), illumination
wavelength (1.047 to 11.0 μm), minority carrier diffusion length (8 to 90 μm), and diode pitch. It is found that the dominant
feature influencing the value of crosstalk is the distance between the region of photogeneration and the collecting p-n junction. 相似文献
10.
G. Destéfanis A. Astier J. Baylet P. Castelein J. P. Chamonal E. DeBorniol O. Gravand F. Marion J. L. Martin A. Million P. Rambaud F. Rothan J. P. Zanatta 《Journal of Electronic Materials》2003,32(7):592-601
In this article, we present recent developments of the research in France at LETI infrared laboratory in the field of complex
third-generation HgCdTe IRCMOS focal plane arrays (FPAs). We illustrate this with three prototypes of FPAs made at LETI, which
have involved some technological improvements from the standard process today in production at Sofradir. We present, using
molecular-beam epitaxy (MBE) growth, a 128 × 128 dual-band infrared (photodetector)-complementary metal oxide semiconductor
(IRCMOS) with a pitch of 50 μm operating within 2–5 μm. Using the more conventional liquid-phase epitaxy (LPE) growth, we
show a new generation of high-performance long linear arrays (1500 × 2; pitch, 30 μm) operating in medium-wavelength infrared
(MWIR) or long-wavelength infrared (LWIR) bands based on a modular architecture of butted HgCdTe detection circuit and SiCMOS
multiplexers. Finally, we present for the first time a megapixel (1000 × 1000) FPA with a pitch of 15 μm operating in the
MWIR band that exhibits a very high performance and pixel operability. 相似文献
11.
Over the last several years cooled applications of HgCdTe at low temperatures have proliferated. Having low fundamental dark
current at any given wavelength and temperature makes HgCdTe attractive for high temperature applications as well. We are
exploring detectors with cut off wavelengths from the near to middle infrared region (∼1.5 to ∼4 μm). Theory allows applications
from low light level imaging in starlight and “nightglow” to thermal imaging, both with useful sensitivities at room temperature.
The demonstrated possibility of reducing or eliminating traditional recombination processes (radiative and Auger) further
increase the attractiveness of HgCdTe. Current materials technology shows some evidence that these sensitivities can be attained.
Current detector technology, being limited by SRH traps, appears to require modest cooling (to about 250K). Improved materials
and processes should eliminate the need for even this cooling. 相似文献
12.
R. D. Rajavel D. Jamba O. K. Wu J. A. Roth P. D. Brewer J. E. Jensen C. A. Cockrum G. M. Venzor S. M. Johnson 《Journal of Electronic Materials》1996,25(8):1411-1415
A robust process has been developed for the reproducible growth of in-situ doped Hg1−xCdxTe:As alloys by molecular beam epitaxy. Net hole concentrations in excess of 5 x 1017 cm−3, with peak mobilities >200 cm2/Vs were measured in Hg0.74Cd0.26Te:As films. The p-type layers were twin-free and consistently exhibit narrow x-ray rocking curves (<40 arc sec). The reproducible
growth of small lots of p-on-n LWIR detector structures has been established. For a typical lot consisting of 13 layers, the
average x-value of the n-type base layer was 0.226 with a standard deviation of 0.003. The lateral compositional uniformity
across a 2.5 cm × 2.5 cm wafer was × = +- 0.0006. High performance p-on-n LWIR diodes were fabricated that exhibited RoAo values (0-fov at 78K) as large as 350 Q cm2 at 10.4 μm. 相似文献
13.
E. P. G. Smith G. M. Venzor P. M. Goetz J. B. Varesi L. T. Pham E. A. Patten W. A. Radford S. M. Johnson A. J. Stoltz J. D. Bensen J. H. Dinan 《Journal of Electronic Materials》2003,32(7):821-826
A combination of mechanical experiments and fabrication of very-long-wavelength infrared (VLWIR) HgCdTe-infrared detectors
has been used to investigate the interaction between various unit-cell design and dry-etch process variables on final unit-cell
dimensions and detector performance. Etch rate, which determines the process time required to achieve a specified etch depth,
was found to be a function of both the trench width opening used to delineate an individual detector element in a focal-plane
array (FPA) and the mesa profile observed during etching. Current-voltage (I-V) probe data at 78 K demonstrated the successful
fabrication of 30 μm unit-cell, VLWIR-HgCdTe diodes with mesa delineation performed by dry etching. The breakdown performance
of these diodes is sensitive to trench width and dry-etch process time. 相似文献
14.
Progress in MOVPE of HgCdTe for advanced infrared detectors 总被引:1,自引:0,他引:1
This paper reviews the significant progress made over the past five years in the development of metalorganic vapor phase epitaxy
(MOVPE) for the in situ growth of HgCdTe p-n junction devices for infrared detector arrays. The two basic approaches for MOVPE growth of HgCdTe,
the interdiffused multilayer process (IMP), and direct alloy growth (DAG) are compared. The paper then focuses on the progress
achieved with the IMP approach on lattice-matched CdZnTe substrates. The benefits of the precursors ethyl iodide (EI) and
tris-dimethylaminoarsenic (DMAAs) for controlled iodine donor doping and arsenic acceptor doping at dopant concentrations relevant
for HgCdTe junction devices are summarized along with the electrical and lifetime properties of n-type and p-type HgCdTe films
grown with these precursors. The relative merits of the two CdZnTe substrate orientations we have used, the (211)B and the
(100) with 4°–8° misorientation are compared, and the reasons why the (211)B is preferred are discussed. The growth and repeatability
results, based on secondary ion mass spectrometry analysis, are reported for a series of double-heterojunction p-n-N-P dual-band
HgCdTe films for simultaneous detection in the 3–5 μm and 8–10 μm wavelength bands. Finally, the device characteristics of
MOVPE-IMP in situ grown p-on-n heterojunction detectors operating in the 8–12 μm band are reviewed and compared with state-of-the-art liquid
phase epitaxial grown devices. 相似文献
15.
We discuss analytic and numerical models for HgCdTe photodiodes and present examples of their application. Analytic models
can account for the performance obtained by many device architectures. Numerical and analytic models agree in predicting several
aspects of device performance, such as diffusion limited dark current, confirming the approximations used in deriving the
analytic models. Areas are noted where improvement in the numerical models would allow application to a wider range of device
simulations. Useful results are obtained from the numerical simulators that cannot be obtained from our analytic model. Flux
dependent R0A products are shown to be a direct result of bias dependent quantum efficiency, a mechanism that is much more evident in
heterojunction device architectures. Material compositional grading is demonstrated to lead to lower signal to noise ratio
in devices designed to detect a particular infrared wavelength. We also show, particularly for high temperature operation,
that heterojunction detectors can at best equal the performance of well-designed homojunction detectors; so, for photodetector
design, heterojunctions do not offer any inherent performance advantages over homojunctions. Nevertheless, heterostructures,
though ideally not required, may be helpful in achieving high performance in practice. 相似文献
16.
Isolation and control of voids and void-hillocks during molecular beam epitaxial growth of HgCdTe 总被引:2,自引:0,他引:2
D. Chandra F. Aqariden J. Frazier S. Gutzler T. Orent H. D. Shih 《Journal of Electronic Materials》2000,29(6):887-892
Formation of small voids and defect complexes involving small voids during the molecular beam epitaxial growth of mercury
cadmium telluride on cadmium zinc telluride was investigated. Some of these defects were demonstrated to form away from the
substrate-epi interface. Other defects were demonstrated to close before reaching the top surface without leaving any perturbations
on the surface, thus remaining completely hidden. The voids, which formed away from the substrate-epifilm fixed interface,
nucleated on defects introduced into the film already grown, leading to the formation of defect complexes, unlike the voids
which nucleated at the substrate-epifilm fixed interface. These defect complexes are decorated with high density dislocation
nests. The voids which closed before reaching the film surface usually also nucleated slightly away from the film-substrate
interface, continued to replicate for a while as the growth progressed, but then relatively rapidly closed off at a significant
depth from the film surface. These voids also appeared to form defect complexes with other kinds of defects. Correlations
between these materials defects and performance of individual vertically integrated photodiode (VIP) devices were demonstrated,
where the relative location of these defects with respect to the junction boundary appears to be particularly important. Elimination
or reduction of fluctuations in relative flux magnitudes or substrate temperature, more likely during multi-composition layer
growth, yielded films with significantly lower defect concentrations. 相似文献
17.
采用砷(As)掺杂HgCdTe材料研制了响应截止波长为12.5 μm,规格为256×1的长波红外光电二极管阵列.实验设计了一种新的pn结测量方法,测量发现砷掺长波HgCdTe材料离子注入形成pn结深度在3.6~5.3 μm之间,而其最大横向尺寸大约是设计尺寸的1.3倍.实验采用一种改进的表面处理工艺制备了砷掺HgCdTe长波红外光电二极管阵列,获得了良好的电学性能,该工艺与常规表面处理工艺相比可以使器件峰值阻抗提高2个量级,而-0.5v偏压下的动态电阻可提高约30倍.研究认为,器件性能提高的原因是由于改进工艺可以有效抑制器件表面漏电流. 相似文献
18.
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
19.
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
20.
Bake stability of long-wavelength infrared HgCdTe photodiodes 总被引:2,自引:0,他引:2
A. Mestechkin D. L. Lee B. T. Cunningham B. D. Mac Leod 《Journal of Electronic Materials》1995,24(9):1183-1187
The bake stability was examined for HgCdTe wafers and photodiodes with CdTe surface passivation deposited by thermal evaporation.
Electrical and electrooptical measurements were performed on various long-wavelength infrared HgCdTe photodiodes prior to
and after a ten-day vacuum bakeout at 80°C, similar to conditions used for preparation of tactical dewar assemblies. It was
found that the bakeout process generated additional defects at the CdTe/ HgCdTe interface and degraded photodiode parameters
such as zero bias impedance, dark current, and photocurrent. Annealing at 220°C under a Hg vapor pressure following the CdTe
deposition suppressed the interface defect generation process during bakeout and stabilized HgCdTe photodiode performance. 相似文献