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71.
R. Grill J. Franc I. Turkevych P. HöSchl E. Belas P. Moravec 《Journal of Electronic Materials》2005,34(6):939-943
The possibility to prepare semi-insulating CdTe with a deep-level doping below the limit 1013 cm−3 demanded in detector industry is studied theoretically within quasi-chemical formalism. We show that proper thermal treatment,
including low temperature (ca 200°C) dwell, allows fulfillment of this demand also in 7N or less purity materials. The procedure
is demonstrated in Te-rich CdTe doped with a shallow donor. Its principle is based on enhanced defect selfcompensation, which
affords at sufficiently low temperature extremely high compensation of shallow defects. New high-temperature transport data
are used to refine on previous native defect properties for the modeling. The analysis of diffusion rates at lowered temperature
approves the model for a real-time experimental verification. 相似文献
72.
Indium alloyed to n-type CdTe of about 1016 cm-3 electron concentration provides a contact resistivity of about 7 x 10-3 ohm cm2. This is achieved by alloying for 10 minutes at 150-450‡C in a sealed ampoule with an overpressure of cadmium. If the alloying
is done in an open tube H2 flow without a Cd vapor overpressure, alloying temperatures above 250‡C cause the contact resistance to rise as cadmium vacancies
increase the compensation in the CdTe. Further improvement of the contact resistivity to 1 x 10-3 ohm cm is obtained by a 900‡C diffusion of In into the n-CdTe (electron concentration 1016 cm-3 before the diffusion). 相似文献
73.
Dual-band infrared detectors made on high-quality HgCdTe epilayers grown by molecular beam epitaxy on CdZnTe or CdTe/Ge substrates 总被引:2,自引:0,他引:2
P. Ballet F. Noël F. Pottier S. Plissard J. P. Zanatta J. Baylet O. Gravrand E. De Borniol S. Martin P. Castelein J. P. Chamonal A. Million G. Destefanis 《Journal of Electronic Materials》2004,33(6):667-672
In this paper, we present all the successive steps for realizing dual-band infrared detectors operating in the mid-wavelength
infrared (MWIR) band. High crystalline quality HgCdTe multilayer stacks have been grown by molecular beam epitaxy (MBE) on
CdZnTe and CdTe/Ge substrates. Material characterization in the light of high-resolution x-ray diffraction (HRXRD) results
and dislocation density measurements are exposed in detail. These characterizations show some striking differences between
structures grown on the two kinds of substrates. Device processing and readout circuit for 128×128 focal-plane array (FPA)
fabrication are described. The electro-optical characteristics of the devices show that devices grown on Ge match those grown
on CdZnTe substrates in terms of responsivity, noise measurements, and operability. 相似文献
74.
S. Velicu T. S. Lee C. H. Grein P. Boieriu Y. P. Chen N. K. Dhar J. Dinan D. Lianos 《Journal of Electronic Materials》2005,34(6):820-831
The cost and performance of hybrid HgCdTe infrared (IR) focal plane arrays are constrained by the necessity of fabricating
the detector arrays on a CdZnTe substrate. These substrates are expensive, fragile, available only in small rectangular formats,
and are not a good thermal expansion match to the silicon readout integrated circuit. We discuss in this paper an IR sensor
technology based on monolithically integrated IR focal plane arrays that could replace the conventional hybrid focal plane
array technology. We have investigated the critical issues related to the growth of HgCdTe on Si read-out integrated circuits
and the fabrication of monolithic focal plane arrays: (1) the design of Si read-out integrated circuits and focal plane array
layouts; (2) the low-temperature cleaning of Si(001) wafers; (3) the growth of CdTe and HgCdTe layers on read-out integrated
circuits; (4) diode creation, delineation, electrical, and interconnection; and (4) demonstration of high yield photovoltaic
operation without limitation from earlier preprocessing such as substrate cleaning, molecular beam epitaxy (MBE) growth, and
device fabrication. Crystallographic, optical, and electrical properties of the grown layers will be presented. Electrical
properties for diodes fabricated on misoriented Si and readout integrated circuit (ROIC) substrates will be discussed. The
fabrication of arrays with demonstrated I–V properties show that monolithic integration of HgCdTe-based IR focal plane arrays
on Si read-out integrated circuits is feasible and could be implemented in the third generation of IR systems. 相似文献
75.
R. N. Jacobs E. W. Robinson M. Jaime-Vasquez A. J. Stoltz J. Markunas L. A. Almeida P. R. Boyd J. H. Dinan L. Salamanca-Riba 《Journal of Electronic Materials》2006,35(6):1474-1480
A vacuum-compatible process for carrying out lithography on Hg1−xCdxTe and CdTe films was previously demonstrated. It was shown that hydrogenated amorphous silicon (a-Si:H) could be used as
a dry resist by projecting a pattern onto its surface using excimer laser irradiation and then developing that pattern by
hydrogen plasma etching. Pattern transfer to an underlying Hg1−xCdxTe film was then carried out via Ar/H2 plasma etching in an electron cyclotron resonance (ECR) reactor. Despite the successful demonstration of pattern transfer,
the possibility of inducing harmful effects in the Hg1−xCdxTe film due to this vacuum lithography procedure had not been explored. Here we present structural and surface compositional
analyses of Hg1−xCdxTe films at key stages of the a-Si:H vacuum lithography procedure. X-ray diffraction double crystal rocking curves taken before
and after a-Si:H deposition and after development etching were identical, indicating that bulk structural changes in the Hg1−xCdxTe film are not induced by these processes. Cross-section transmission electron microscopy studies show that laser-induced
heating in the 350 nm thick a-Si:H overlayer is not sufficient to cause structural damage in the underlying Hg1−xCdxTe surface. In vacuo surface analysis via Auger electron spectroscopy and ion scattering spectroscopy suggest that the hydrogen
plasma development process produces Hg-deficient surfaces but does not introduce C contamination. However, after ECR plasma
etching into the Hg1−xCdxTe film, the measured x value is much closer to that of the bulk. 相似文献
76.
E. D. Jones J. Malzbender N. Shaw P. Capper J. B. Mullin 《Journal of Electronic Materials》1995,24(9):1225-1229
Studies on the diffusion of iodine into CdTe, mercury cadmium telluride (Hg0.8Cd0.2Te, referred to as MCT) and zinc cadmium telluride (Zn0.5Cd0.95Te, referred to as ZCT) in the temperature range of 20 to 600°C are compared and discussed. The concentration profiles were
measured using a radiotracer sectioning technique. As with the diffusion studies using the halogens into CdTe, the profiles
were composed of four parts to which a computer package consisting of the sum of four complementary error functions (erfc)
gave satisfactory fits. The diffusivity for the diffusion of iodine into MCT was faster than for the diffusion into CdTe,
which was faster than for the diffusion into ZCT. The high diffusivity for the fastest profile part at 20°C indicates that
when iodine is diffused from the vapor into these materials, it is not a suitable long term stable dopant in devices where
sharp junctions are required. 相似文献
77.
Substrate issues for the growth of mercury cadmium telluride 总被引:1,自引:0,他引:1
R. Triboulet A. Tromson-Carli D. Lorans T. Nguyen Duy 《Journal of Electronic Materials》1993,22(8):827-834
Close lattice matching and lattice compatibility with mercury cadmium telluride (MCT) make CdTe and related alloys ideal substrate
materials for growth of MCT layers for the purpose of making high-performance second-generation infrared detectors. However,
the limitations in the properties of CdTe and the difficulties in its bulk growth have prompted extensive research in the
area of alternative substrates. Some basic relevant characteristics of substrates such as sapphire, GaAs, and silicon are
compared and the possibilities and problems associated with each material are analyzed in the light of the most recent results
in the field. 相似文献
78.
We have grown strained Cd1-xZnxTe(x ≈ 0.2)/CdTe single and multiple quantum wells by molecular beam epitaxy. GaAs was used as a substrate. The well widths were systematically increased until the critical thickness was exceeded. Low-temperature (liquid helium) photoluminescence (PL) spectroscopy was used to characterize the films. Two prominent PL peaks were observed: one arising from the quantum well and the other from the barrier material. The energy of the quantum well luminescence is consistent with theory when strain is included. The critical layer thickness for the CdTe quantum wells was found to be between 150 and 175 å, in agreement with the model of Matthews and Blakeslee. 相似文献
79.
Using the molecular beam epitaxial (MBE) technique, CdTe and Hg1-xCdxTe have been grown on Cr-doped GaAs (100) sub-strates. A single effusion cell charged with polycrystal-line CdTe is used for the growth of CdTe films. The CdTe films grown at 200 °C with a growth rate of ~ 2 μm/hr show both streaked and “Kikuchi” patterns, indicating single crystalline CdTe films are smoothly grown on the GaAs sub-strates. A sharp emission peak is observed at near band-edge (7865 Å, 1.577 eV) in the photoluminescence spectrum at 77 K. For the growth of Hg1-xCdxTe films, separate sources of HgTe, Cd and Te are used. Hg0.6Cd0.4Te films are grown at 50 °C with a growth rate of 1.7 μm/hr. The surfaces are mirror-smooth and the interfaces between the films and the substrates are very flat and smooth. As-grown Hg0.6Cd0.4Te films are p-type and converted into n-type by annealing in Hg pressure. Carrier concentration and Hall mobility of an annealed Hg0.6Cd0.4Te film are 1 × 1017 cm?3 and 1000 cm2/V-sec at 77 K, respectively. 相似文献
80.
Using first-principles calculations based on density functional theory, we have investigated the nature of H defects in CdTe.
The formation energy calculations indicate that the ground state position of the H inside the CdTe lattice depends on charge
state: the lowest energy position for H0 and H+ is at the bond center site, while H− prefers the tetrahedral interstitial site with Cd nearest neighbors (TCd). We find that H in CdTe acts as an amphoteric impurity. In p-type samples, H is in a positive charge state, acting as a donor to neutralize the free holes in the valence band, and in
n-type samples H acquires an electron, compensating the donors in the sample. 相似文献