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1.
K. M. Yu J. Wu W. Walukiewicz J. W. Beeman J. W. Ager E. E. Haller I. Miotkowski A. Ramdas 《Journal of Electronic Materials》2002,31(7):754-758
We have successfully synthesized highly mismatched Cd1−yMnyOxTe1−x alloys by high-dose implantation of O ions into Cd1−yMnyTe crystals. In crystals with y>0.02, incorporation of O causes a large decrease in the bandgap. The bandgap reduction increases
with y; the largest value observed is 190 meV in O+-implanted Cd0.38Mn0.62Te. The results are consistent with the band anticrossing (BAC) model, which predicts that a repulsive interaction between
localized states of O located above the conduction-band edge and the extended states of the conduction band causes the bandgap
reduction. A best fit of the measured bandgap energies of the O-ion-synthesized Cd1−yMnyOxTe1−x alloys using the BAC model for y<0.55 suggests an activation efficiency of only ∼5% for implanted O in Cd1−yMnyTe. 相似文献
2.
Jijun Zhang Wanqi Jie Lijun Luan Tao Wang Dongmei Zeng 《Journal of Electronic Materials》2008,37(8):1158-1162
Cd1−x
Mn
x
Te is a typical diluted magnetic semiconductor, as well as substrate for the epitaxial growth of Hg1−x
Cd
x
Te. In this paper, the homogeneity of a Cd1−x
Mn
x
Te (x = 0.2) single-crystal ingot grown by the vertical Bridgman method was studied. The crystal structure and quality of the as-grown
ingot were evaluated. Near-infrared (NIR) transmission spectroscopy was adopted to develop a simple optical determination
of the Mn concentration in the as-grown ingot. A correlation equation between cut-off wavelength λ
co from NIR transmission spectra and Mn concentration by inductively coupled plasma atomic emission spectrometry (ICP-AES) was
established. Using this equation, we investigated the Mn concentration distribution in both the axial and radial directions
of the ingot. It was found that the segregation coefficient of Mn in the axial direction of the ingot was 0.95, which is close
to unity. The Mn concentration variation in the wafers from the middle part of the ingot was 0.001 mole fraction. All these
results proved that homogeneous Cd0.8Mn0.2Te crystals can be grown from the vertical Bridgman method. 相似文献
3.
G. V. Beketov A. E. Belyaev S. A. Vitusevich S. V. Kavertsev S. M. Komirenko 《Semiconductors》1997,31(3):218-221
The results of an experimental study of samples of MnxHg1−x
Te films grown by liquid-phase epitaxy on a Cd0.96Zn0.04Te substrate are presented. It shows that, as a result of the diffusion of cadmium from the substrate, a CdxMnyHg1−x−y
Te film with a variable band-gap layer is formed close to the 〈epitaxial-film〉-substrate interface. The appearance of this
variable band gap is revealed by the transport phenomena. The temperature dependence of the band gap E
g
(T) is determined in a linear approximation on T from the results of a theoretical analysis of the temperature dependences of the free-carrier concentration and mobility.
It is shown that averaging the semiempirical dependences for the ternary compounds with the extreme compositions, using the
virtual-crystal approximation, can produce large errors when determining E
g
(T) in a specific semiconductor.
Fiz. Tekh. Poluprovodn. 31, 268–272 (March 1997) 相似文献
4.
H. R. Vydyanath J. A. Ellsworth R. F. Fisher J. J. Kennedy C. J. Johnson G. T. Neugebauer 《Journal of Electronic Materials》1993,22(8):1067-1071
Cd1−xZnxTe compounds of different compositions have been prepared at temperatures ranging from 400 to 1000°C by annealing elemental
Te in sealed quartz ampoules, in an atmosphere comprising vapors of Cd and Zn whose partial pressures were varied by varying
the composition of the binary Cd1−yZny alloys which provided the Cd and Zn vapors in these annealing experiments. The chemical compositions of the resulting Cd1−xZnxTe compounds have been analyzed using electron probe microanalytical techniques. Results indicate that presence of a 0.5%Zn
along with Cd in a closed or semi-closed system may prove to be beneficial in preventing decomposition and/or formation of
a metal/non metal phase during annealing of Cd0.96Zn0.04 Te substrates. Using the thermodynamic data in the literature for the binary Cd1−yZny alloys and with the assumption that the activities of the Cd and Zn components are weakly dependent on temperature, the partial
pressures of Cd and Zn in equilibrium with the Cd1−xZnxTe compounds at various temperatures have been evaluated. 相似文献
5.
S. M. Johnson J. L. Johnson W. J. Hamilton D. B Leonard T. A. Strand E. A. Patten J. M. Peterson J. H. Durham V. K. Randall T. J. deLyon J. E. Jensen M. D. Gorwitz 《Journal of Electronic Materials》2000,29(6):680-686
As the number of bands and the complexity of HgCdTe multicolor structures increases, it is desirable to minimize the lattice
mismatch at growth interfaces within the device structure in order to reduce or eliminate mismatch dislocations at these interfaces
and potential threading dislocations that can degrade device performance. To achieve this we are investigating the use of
Hg1−x−yCdxZnyTe quaternary alloys which have an independently tunable lattice constant and bandgap. Lattice matching in Hg1−x−yCdxZnyTe structures can be achieved using small additions of Zn (y<0.015) to HgCdTe ternary alloys. We have investigated some of
the basic properties of Hg1−x−yCdxZnyTe materials with x≈0.31 and 0≤y≤0.015. The quaternary layers were grown on (112)CdZnTe substrates using MBE and the amount
of Zn in the layers was determined from calibrated SIMS measurements. As expected, the lattice constant decreased and the
bandgap increased as Zn was added to HgCdTe to form Hg1−x−yCdxZnyTe. Hall-effect results for both n-type (In) and p-type (As) Hg1−x−yCdxZnyTe layers were very similar to HgCdTe control samples. We have also utilized x-ray rocking curve measurements with (246) asymmetric
reflections as a novel sensitive technique to determine the correct amount of Zn needed to achieve lattice matching at an
interface. MWIR/LWIR n-p-n two-color triple-layer heterojunction structures were grown to evaluate the effects of minimizing
the lattice mismatch between the widest bandgap p-type collector layer, using Hg1−x−yCdxZnyTe, and the HgCdTe MWIR and LWIR collector layers and compared to structures that did not incorporate the quaternary. Sequential
mode two-color detectors were fabricated using a 256 × 256, 30 μm unit cell design. There were several interesting findings.
Macro defects predominantly affected the LWIR band (Band 2) operability and had little effect on the MWIR band (Band 1). The
incorporation of Hg1−x−yCdxZnyTe p-type collector layers had little effect on MWIR detector performance, but overall the LWIR performance was generally
better. These initial detector results indicate that the use of Hg1−x−yCdxZnyTe alloys in multicolor detector structures are potentially promising and should be pursued further. 相似文献
6.
Critical thickness in the HgCdTe/CdZnTe system 总被引:2,自引:0,他引:2
M. A. Berding W. D. Nix D. R. Rhiger S. Sen A. Sher 《Journal of Electronic Materials》2000,29(6):676-679
We present an analysis of the critical thickness of Hg1−xCdxTe on Cd1−yZnyTe substrates as a function of x and y and show that a very tight control of the substrate composition is needed to produce
dislocation-free epi-layers. Hg1−xCdxTe layers on relaxed underlayers of different compositions of Hg are also examined. 相似文献
7.
Planar melt crystallization is used to grow single crystals of Cd-Mg-Mn-Te quaternary alloys along the pseudobinary sections
Cd0.75 − x
Mg
x
Mn0.25Te, Cd0.75 − x
Mg0.25Mn
x
Te, and Cd1 − 2x
Mg
x
Mn
x
Te. The first photosensitive structures, i.e., In/CdMgMnTe Schottky barriers, are fabricated within each indicated single-crystal
section. The spectral dependences of the relative quantum efficiency of photoconversion are measured, and the broadband photosensitivity
of the new structures is detected. Based on the spectral dependences of the photosensitivity, the nature of the meson transitions
is discussed and the corresponding band gaps are determined. The applicability of grown single crystals of CdMgMnTe quaternary
alloys to broadband photoconverters of optical radiations is ascertained. 相似文献
8.
A. G. Bluiett U. Hömmerich R. T. Shah S. B. Trivedi S. W. Kutcher C. C. Wang 《Journal of Electronic Materials》2002,31(7):806-810
We are engaged in a systematic study of the optical and laser properties of Cr2+-doped cadmium chalcogenides. Previously, we demonstrated quasi-continuous wave lasing from Cr2+-doped Cd0.55Mn0.45Te with slope efficiencies as high as 64% and a laser tuning range from 2,170–3,010 nm. In this paper, we report the first
demonstration of lasing from Cr:CdTe at room temperature. Pulsed-laser operation was obtained with a free-running spectrum
centered at 2,535 nm. The slope efficiency of the laser was low (∼1%) because of large parasitic losses at the laser wavelength.
The spectroscopic properties of Cr:CdTe are favorable for laser applications because of a large emission cross section (∼2.5
× 10−18 cm2) and a high emission-quantum yield (∼88%). In addition, CdTe can easily incorporate Cr ions either through melt growth or
diffusion doping. Along with our results on Cr2+:CdTe, we report on the optical properties of several other Cr2+-doped II-VI semiconductors (ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, Cd0.9Zn0.1Te, Cd0.65Mg0.35Te, Cd0.85Mn0.15Te, and Cd0.55Mn0.45Te) and compare them for applications as solid-state laser materials. 相似文献
9.
Transition metal doped cadmium manganese telluride: A new material for tunable mid-infrared lasing 总被引:2,自引:0,他引:2
S. B. Trivedi S. W. Kutcher C. C. Wang G. V. Jagannathan U. Hömmerich A. Bluiett M. Turner Jae Tae Seo Kenneth L. Schepler Bryce Schumm Phillip R. Boyd Gary Green 《Journal of Electronic Materials》2001,30(6):728-732
Relatively new materials for mid-infrared tunable lasing using chromium-doped Cd1-xMnxTe and cobalt-doped Cd1-xMnxTe have been developed. Previously, ZnS and ZnSe were used as host materials for chromium to produce mid-infrared (MIR) lasing.
Compared to these materials, large diameter CdMnTe is easier to grow (using the Bridgman technique) and can be made more homogeneous.
Moreover, the ternary nature of Cd1-xMnxTe offers the unique opportunity to optimize the optical properties of the material through variation of chemical composition
and lattice parameter. Using Cd0.55Mn0.45Te:Cr, we have demonstrated room temperature lasing from 2.1 to 3.0 m, and we have demonstrated quasi-continuous wave (cw)
lasing. To our knowledge, the observed tuning range (∼840 nm) of Cr2+:Cd0.55Mn0.45Te is the largest ever reported from a transition metal ion laser. Furthermore, this is the first time that a room temperature
quasi-cw laser operating at 3 m has been demonstrated using this type of material. Also, preliminary work on Cd0.55Mn0.45Te:Co indicates its potential for tunable mid-infrared lasing around 3600 nm at cryogenic temperatures. Results from inductively
coupled plasma mass spectrometry (ICP-MS), which determine the concentration of dopant that has been incorporated in to the
host lattice, will be reported, as will the materials characterization and lasing results. The processing issues for optimizing
the laser performance in these material systems will also be discussed. 相似文献
10.
E. P. Skipetrov M. G. Mikheev F. A. Pakpour L. A. Skipetrova N. A. Pichugin E. I. Slyn’ko V. E. Slyn’ko 《Semiconductors》2009,43(3):297-304
Magnetic properties of Pb1 − x − y
Ge
x
Cr
y
Te alloys (x = 0.02–0.20, y = 0.01–0.08) were studied. It was detected that the magnetic susceptibility of alloys consists of two contributions: the
paramagnetic Curie-Weiss part (the temperature region is T < 50 K) caused, probably, by the Cr3+ ion paramagnetism, and the high-temperature ferromagnetic part (T < 300 K). The dependences of the concentration of magnetic centers on the composition of the matrix were obtained from the
paramagnetic and ferromagnetic contributions. It was shown that a decrease in the concentration of paramagnetic centers can
be, at least qualitatively, explained by the transformation of the electronic structure as the germanium concentration increases.
A phenomenological model was suggested, which explains the behavior of magnetic properties as the chromium content increases,
and possible mechanisms of ferromagnetic ordering in studied alloys are discussed.
Original Russian Text ? E.P. Skipetrov, M.G. Mikheev, F.A. Pakpour, L.A. Skipetrova, N.A. Pichugin, E.I. Slyn’ko, V.E. Slyn’ko,
2009, published in Fizika i Tekhnika Poluprovodnikov, 2009, Vol. 43, No. 3, pp. 316–323. 相似文献
11.
A. Hossain Y. Cui A.E. Bolotnikov G.S. Camarda G. Yang D. Kochanowska M. Witkowska-Baran A. Mycielski R.B. James 《Journal of Electronic Materials》2009,38(8):1593-1599
CdMnTe offers several potential advantages over CdZnTe as a room- temperature gamma-ray detector, but many drawbacks in its
growth process impede the production of large, defect-free single crystals with high electrical resistivity and high electron
lifetimes. Here, we report our findings of the defects in several vanadium-doped as-grown as well as annealed Cd1−x
Mn
x
Te crystals, using etch pit techniques. We carefully selected single crystals from the raw wafer to fabricate and test as
a gamma-ray detector. We describe the quality of the processed Cd1−x
Mn
x
Te surfaces, and compare them with similarly treated CdZnTe crystals. We discuss the characterization experiments aimed at
clarifying the electrical properties of fabricated detectors, and evaluate their performance as gamma-ray spectrometers. 相似文献
12.
The effects of atomic hydrogen (H) and Br/methanol etching on Hg1−x
Cd
x
Te films were investigated using x-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Exposure of an
as-received Hg1−x
Cd
x
Te sample to H + H2 resulted in H-induced TeO2 reduction. The oxide reduction was first order with respect to H + H2 exposure. Exposure to H + H2 after etching the Hg1−x
Cd
x
Te film in a Br/methanol solution induced Hg and C depletion. Hg and C removal was also observed after completely reducing
the TeO2 on the as-received sample. The removal process was hindered by the formation of a Cd-rich overlayer on both etched and unetched
surfaces. 相似文献
13.
T. Ohnishi M. Naito S. Mizusaki Y. Nagata Y. Noro 《Journal of Electronic Materials》2011,40(5):915-919
The magnetic, transport, and thermoelectric properties of Ca1−x
Sr
x
Ru1−y
Mn
y
O3 have been investigated. Ferromagnetism with relatively high T
C (>200 K) was introduced by Mn doping. In particular, ferromagnetism appeared in the Ca0.5Sr0.5Ru1−y
Mn
y
O3 system at y > 0.2. The maximum T
C (=270 K) was recorded for a specimen of Ca0.5Sr0.5Ru0.4Mn0.6O3. The ferromagnetism seems to be due to the mixed-valence states of Mn3+, Mn4+, Ru4+, and Ru5+ ions. The metallic character of Ru-rich specimens was suppressed by Mn substitution, and the system was transformed into
a semiconductor at relatively low Mn content near y = 0.1. Specimens with higher Mn content (y > 0.8) had large thermoelectric power (50 μV K−1 to 130 μV K−1 at 280 K) accompanied by relatively low resistivity (0.03 Ω cm to 1 Ω cm). The Ca0.5Sr0.5Ru1−y
Mn
y
O3 system seems to have good potential as a thermoelectric material for use above 300 K. 相似文献
14.
S. A. Ringel R. Sudharsanan A. Rohatgi W. B. Carter 《Journal of Electronic Materials》1990,19(3):259-263
Polycrystalline films of Cd1-x
Zn
x
Te (x = 0–0.4) and Cd1-x
Mn
x
Te (x = 0–0.25) were grown by MBE and MOCVD, respectively, on CdS/SnO2/glass substrates to investigate their feasibility for solar cell applications. The compositional uniformity and interface
quality of the films were analyzed by x-ray diffraction, surface photovoltage, and Auger depth profile measurements to establish
a correlation between growth conditions and lattice constant, atomic concentration, and bandgap of the ternary films. MBE-grown
polycrystalline Cd1-x
Zn
x
Te films showed a linear dependence between Zn/(Cd + Zn) beam flux ratio, Zn concentration in the film, and the bandgap. Polycrystalline
Cd1-x
Zn
x
Te films grown at 300° C showed good compositional uniformity in contrast to compositionally non-uniform Cd1-x
Mn
x
Te films grown by MOCVD in the temperature range of 420–450° C. The MBE-grown Cd1-x
Zn
x
Te interface also showed significantly less interdiffusion compared to the MOCVD-grown Cd1-x
Mn
x
Te/CdS interface, where preferential exchange between Cd from the CdS layer and Mn from the Cd1-x
Mn
x
Te film was observed. The compositional uniformity of MOCVD-grown polycrystalline Cd1-x
Mn
x
Te films grown on CdS/SnO2/glass substrates was found to be a strong function of the growth conditions as well as the Mn source. 相似文献
15.
S. Velicu C.H. Grein J. Zhao Y. Chang S.-Y. An A. Yadav K. Pipe W. Clark 《Journal of Electronic Materials》2008,37(9):1504-1508
We present a study on the thermoelectric properties of n-type Hg0.75Cd0.25 Te/Hg0.7Cd0.3Te superlattices (SLs). This material system was chosen because HgCdTe is the primary material used in high-performance infrared
imaging applications. HgCdTe-based devices can be directly grown on Hg1−x
Cd
x
Te/Hg1−y
Cd
y
Te SL coolers using advanced growth methods such as molecular-beam epitaxy (MBE), making the monolithic integration of infrared
sensors and thermoelectric elements possible. Also, the thermoelectric figure of merit ZT for Hg0.75Cd0.25Te/Hg0.7Cd0.3Te SLs is predicted to reach values of 2.09, more than two times greater than that achieved in the best thermoelectric devices
based on bulk Bi2Te3. This large ZT is due to the unique and superior electrical and thermal properties of the HgCdTe system, which has not yet been experimentally
explored in any great depth as a thermoelectric material. We used a Riber 32P MBE system equipped with a Hg valved cell, reflection
high-energy electron diffraction, infrared pyrometer and in situ spectroscopic ellipsometry to grow the thermoelectric structures. MBE was chosen as a growth technique since it allows for
the lowest growth temperature compared with other methods, which limits interdiffusion at the interfaces, thereby allowing
for a precise control over electrical and thermal properties. Thermal devices were fabricated using standard photolithography
and etching techniques. Thermal properties were evaluated using a differential technique. A thermal conductivity of 0.82 ± 0.07 W/m K
and a Seebeck coefficient of 811 ± 150 μV/K were measured. Using a measured value of 0.017 Ω cm for the resistivity, an upper bound ZT of 1.4 is estimated.
An erratum to this article can be found at 相似文献
16.
S. Dvoretsky N. Mikhailov Yu. Sidorov V. Shvets S. Danilov B. Wittman S. Ganichev 《Journal of Electronic Materials》2010,39(7):918-923
We zone-engineered HgCdTe/HgTe/HgCdTe quantum wells (QWs) using the molecular-beam epitaxy (MBE) method with in situ high-precision ellipsometric control of composition and thickness. The variations of ellipsometric parameters in the ψ–Δ
plane were represented by smooth broken curves during HgTe QW growth with abrupt composition changes. The form of the spiral
fragments and their extensions from fracture to fracture revealed the growing layer composition and its thickness. Single
and multiple (up to 30) Cd
x
Hg1−x
Te/HgTe/Cd
x
Hg1−x
Te QWs with abrupt changes of composition were grown reproducibly on (013) GaAs substrates. HgTe thickness was in the range
of 16 nm to 22 nm, with the central portion of Cd
x
Hg1−x
Te spacers doped by In to a concentration of 1014 cm−3 to 1017 cm−3. Based on this research, high-quality (013)-grown HgTe QW structures can be used for all-electric detection of radiation
ellipticity in a wide spectral range, from far-infrared (terahertz radiation) to mid-infrared wavelengths. Detection was demonstrated
for various low-power continuous-wave (CW) lasers and high-power THz pulsed laser systems. 相似文献
17.
T. K. Tran A. Parikh S. D. Pearson B. K. Wagner R. G. Benz R. N. Bicknell-Tassius C. J. Summers T. Kelz J. W. Tomm W. Hoerstel P. Schäfer U. Muller 《Journal of Electronic Materials》1996,25(8):1203-1208
We present a study of the electro-optical properties ofHg
1- xCdxTe epitaxial layers and Hg1-x CdxTe/CdTe (0.28 < x < 0.30) superlattice structures by x-ray diffraction, lateral transport and photo- and magneto-luminescence
measurements. Systematic studies of the excitation intensity and magnetic field dependence of the photoluminescence revealed
direct evidence of an excitonic contribution to the observed luminescence in Hg1- xCdxTe epitaxial layers. Similar investigations of the superlattice structures indicated that excitonic corrections were required
to adequately fit the luminescence data. Optical gains of 80 cm−1 were obtained for an excitation intensity of 100 kW/cm2 indicating suitable electro-optical properties for making efficient mid-infrared laser diodes. 相似文献
18.
A. I. Belogorokhov V. A. Kul’bachinskii P. D. Mar’yanchuk I. A. Churilov 《Semiconductors》1998,32(5):488-490
Reflection spectra of single crystals of Hg1−x
MnxTe1−y
Sey (0.01<x<0.14, y=0.01) in the far-infrared range (10–600 cm−1) are investigated at 300 and 77 K. A series of new phonon modes is observed, in addition to the longitudinal and transverse
modes corresponding to the ternary compounds.
Fiz. Tekh. Poluprovodn. 32, 546–548 (May 1998) 相似文献
19.
A study on preparation of Cd0.96Zn0.04Te(211)B substrates for growth of Hg1−xCdxTe epitaxial layers by molecular beam epitaxy (MBE) was investigated. The objective was to investigate the impact of starting
substrate surface quality on surface defects such as voids and hillocks commonly observed on MBE Hg1−xCdxTe layers. The results of this study indicate that, when the Cd0.96Zn0.04Te(211)B substrates are properly prepared, surface defects on the resulting MBE Hg1−xCdxTe films are reduced to minimum (size, ∼0.1 m and density ∼500/cm2) so that these MBE Hg1−xCdx Te films have surface quality as good as that of liquid phase epitaxial (LPE) Hg1−xCdxTe films currently in production in this laboratory. 相似文献
20.
The epitaxial layers of Hg1−xCdxTe (0.17≦×≦0.3) were grown by liquid phase epitaxy on CdTe (111)A substrates using a conventional slider boat in the open
tube H2 flow system. The as-grown layers have hole concentrations in the 1017− 1018 cm−3 range and Hall mobilities in the 100−500 cm2/Vs range for the x=0.2 layers. The surfaces of the layers are mirror-like and EMPA data of the layers show sharp compositional
transition at the interface between the epitaxial layer and the substrate. The effects of annealing in Hg over-pressure on
the properties of the as-grown layers were also investigated in the temperature range of 250−400 °C. By annealing at the temperature
of 400 °C, a compositional change near the interface is observed. Contrary to this, without apparent compositional change,
well-behaved n-type layers are obtained by annealing in the 250−300 °C temperature range. Sequential growth of double heterostructure,
Hgl−xCdxTe/Hgl−yCdyTe on a CdTe (111)A substrate was also demonstrated. 相似文献