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II-VI
compounds are generally compounds formed by elements from II &
VI groups of the Periodic table. Here we mean only binary (ZnSe,
ZnS, ZnTe (also for terahertz applications), CdSe, CdS, CdTe) and ternary
(e. g., CdZnTe or CdSSe) zinc and cadmium chalcogenides that
are wide-gap semiconductors.
Semiconductor single crystals of CdxZn1-xTe (CdZnTe,
CZT, Cadmium Zinc Telluride) are important materials for the development
of far-infrared, visible light, X-ray detectors, and gamma-ray detectors
as medical imaging devices. CdZnTe (CZT, Cadmium Zinc Telluride) radiation
detectors have the advantages of a large absorption coefficient, compact
size and room temperature operation. Currently used high purity Ge and
Si detectors in industry and medical imaging can only work efficiently
at the liquid-nitrogen temperature.
There are many examples of the use of CZT (CdZnTe,
Cadmium Zinc Telluride) detectors in medical imaging and diagnostics,
ranging from simple x-rays carried out in a dentist's office
to cardiac angiography, bone densitometry measurements, and the use
of nuclear medicine to pinpoint areas of activity within the brain to
help characterize conditions such as epilepsy. In addition, the medical
imaging community is interested in developing large area CdZnTe (CZT,
Cadmium Zinc Telluride) detector arrays.
Cadmium zinc telluride (CdZnTe) has become a key detector
technology for hard x-ray and gamma ray astronomy. Astronomers use CZT
(CdZnTe, Cadmium Zinc Telluride) arrays to study the origin of high-energy
gamma-ray bursts. One class of astronomy instruments will use large
area single focal plane array detectors in conjunction with a focusing
optic. CZT (CdZnTe, Cadmium Zinc Telluride) is also suited for high-resolution
measurements and isotope identification in the nuclear industry and
for x-ray radiography applications. The use of single crystal CZT (CdZnTe,
Cadmium Zinc Telluride) as the gamma ray detector material has allowed
the production of very compact prototype imaging systems. Further applications
for CZT (CdZnTe, Cadmium Zinc Telluride) gamma ray detectors include
space flight gamma burst instruments, high-energy x-ray astronomy, and
international nuclear inspection and safeguarding. |
Typical Properties:
| Material
|
ZnS
|
CdS
|
CdSe
|
ZnSe
|
ZnxCd1-xS
|
CdS
|
CdSe
|
CdSxSe1-x
|
CdTe
|
CdTe
|
CdZnTe
|
ZnTe
|
| Growth methods: |
Vertical Bridgman
|
Vertical Bridgman
|
Vertical Bridgman
|
PVT
|
PVT
|
PVT
|
PVT
|
PVT
|
PVT
|
melt
|
PVT
|
Seeded
Vapor Phase
|
| Diameter,
mm |
40
|
40
|
40
|
50
|
50
|
50
|
50
|
50
|
50
|
80
|
50
|
40
|
| Thickness,
mm |
30
|
30
|
30
|
10
|
15
|
40
|
30
|
30
|
10
|
30
|
10
|
15
|
| Optical absorption
(bulk) at 10,6 nm, cm-1 |
<
0.15
|
<
0.007
|
<
0.0015
|
< 0.005
|
-
|
-
|
-
|
-
|
0.01
|
5-10 x 10-4
|
<
0.01
|
-
|
| Resistivity,
Ohm x cm |
-
|
-
|
-
|
-
|
-
|
-
|
-
|
-
|
105
|
5-50x109
|
>
105
|
1x106
|
| Luminescent
emission intensity ration, IEx/Iedge (Iimp) |
-
|
-
|
-
|
>
10
|
>
10
|
>
10
|
>
10
|
>
10
|
-
|
-
|
-
|
-
|
| Dislocation
density, cm-2 |
-
|
-
|
-
|
<
2 x 105
|
<
5 x 105
|
2 x 105
|
<
2 x 105
|
<
2 x 104
|
5 x 104
|
-
|
1 x 104
|
-
|
| Small-angle
boundary density, cm-1 |
-
|
-
|
-
|
<
40
|
<
40
|
70
|
70
|
<
20
|
10
|
-
|
3
|
<
10
|
| Excition
band wavelength in luminescence spectrum, nm |
-
|
490 ± 2
|
690 ± 2
|
444
± 2
|
475 ± 5
|
490 ± 2
|
690 ± 2
|
510 ±
5, 535 ± 10, 560 ± 10, 600 ± 5, 615 +5/-15, 505 ±
5, 625 ± 5 |
-
|
-
|
-
|
-
|
| The variation
of local values for wavelength within the plate, nm |
-
|
-
|
-
|
-
|
±
3
|
-
|
-
|
±
1
|
-
|
-
|
-
|
-
|
| The number
of cavities with size of 15 - 200 m, pcs/pl |
-
|
-
|
-
|
-
|
<
10
|
<=
10
|
none
|
<=
10
|
-
|
-
|
-
|
-
|
From these crystals
we can fabricate different elements or substrates for your needs, for
example:
IR optical components, which operate as elements of high
power CO2-lasers (windows, lenses, prisms, beamspliters etc.)
The different coatings on the elements are available.
ZnSe oriented single crystals rods as IR electrooptical
modulators with max dimensions 5 x 10 x 45 mm3, any crystallographic
orientation, resistivity >1010 Ohm x cm.
ZnSe
oriented cubics with dimensions 10 x 10 x 10 mm3,
high resistivity (>1010 Ohm x cm).
ZnSe substrates to fabricate heterojurunctions with GaAs
film (blue light emission diodes and lasers)-plates 10 x 10 mm2,
10 x 20 mm2, 10 x 30 mm2 or any other form with
thickness of 1÷ 2 mm, (111) or (100) orientation, high resistivity
(>1010 Ohm x cm), free of twins, EPD is 104/ cm2.
CdS oriented plates with low (<10-1 Ohm x cm)
and high resistivity (>108 Ohm x cm)
We supply as-cut blanks up as well as elements made upon customers'
specification.
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