CA1076460A - Cadmium telluride compensated with magnesium or beryllium - Google Patents
Cadmium telluride compensated with magnesium or berylliumInfo
- Publication number
- CA1076460A CA1076460A CA254,751A CA254751A CA1076460A CA 1076460 A CA1076460 A CA 1076460A CA 254751 A CA254751 A CA 254751A CA 1076460 A CA1076460 A CA 1076460A
- Authority
- CA
- Canada
- Prior art keywords
- chloride
- magnesium
- beryllium
- cadmium
- cadmium telluride
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 239000011777 magnesium Substances 0.000 title claims abstract description 24
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 title claims abstract description 23
- 229910052749 magnesium Inorganic materials 0.000 title claims abstract description 23
- 229910052790 beryllium Inorganic materials 0.000 title claims abstract description 19
- ATBAMAFKBVZNFJ-UHFFFAOYSA-N beryllium atom Chemical compound [Be] ATBAMAFKBVZNFJ-UHFFFAOYSA-N 0.000 title claims abstract description 19
- MARUHZGHZWCEQU-UHFFFAOYSA-N 5-phenyl-2h-tetrazole Chemical compound C1=CC=CC=C1C1=NNN=N1 MARUHZGHZWCEQU-UHFFFAOYSA-N 0.000 title claims abstract description 14
- 239000002019 doping agent Substances 0.000 claims abstract description 14
- 239000013078 crystal Substances 0.000 claims abstract description 9
- 239000004065 semiconductor Substances 0.000 claims abstract description 6
- YKYOUMDCQGMQQO-UHFFFAOYSA-L cadmium dichloride Chemical compound Cl[Cd]Cl YKYOUMDCQGMQQO-UHFFFAOYSA-L 0.000 claims description 12
- TWRXJAOTZQYOKJ-UHFFFAOYSA-L Magnesium chloride Chemical compound [Mg+2].[Cl-].[Cl-] TWRXJAOTZQYOKJ-UHFFFAOYSA-L 0.000 claims description 10
- 229910001629 magnesium chloride Inorganic materials 0.000 claims description 5
- VSCWAEJMTAWNJL-UHFFFAOYSA-K aluminium trichloride Chemical compound Cl[Al](Cl)Cl VSCWAEJMTAWNJL-UHFFFAOYSA-K 0.000 claims 8
- LWBPNIJBHRISSS-UHFFFAOYSA-L beryllium dichloride Chemical compound Cl[Be]Cl LWBPNIJBHRISSS-UHFFFAOYSA-L 0.000 claims 8
- JIAARYAFYJHUJI-UHFFFAOYSA-L zinc dichloride Chemical compound [Cl-].[Cl-].[Zn+2] JIAARYAFYJHUJI-UHFFFAOYSA-L 0.000 claims 8
- 229910001627 beryllium chloride Inorganic materials 0.000 claims 4
- 239000011592 zinc chloride Substances 0.000 claims 4
- 235000005074 zinc chloride Nutrition 0.000 claims 4
- 229910052793 cadmium Inorganic materials 0.000 abstract description 14
- BDOSMKKIYDKNTQ-UHFFFAOYSA-N cadmium atom Chemical compound [Cd] BDOSMKKIYDKNTQ-UHFFFAOYSA-N 0.000 abstract description 14
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 abstract description 3
- 229910052782 aluminium Inorganic materials 0.000 abstract description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 abstract description 3
- 238000004519 manufacturing process Methods 0.000 abstract description 3
- 229910052751 metal Inorganic materials 0.000 abstract description 3
- 239000002184 metal Substances 0.000 abstract description 3
- 229910052725 zinc Inorganic materials 0.000 abstract description 3
- 239000011701 zinc Substances 0.000 abstract description 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 abstract description 2
- 229910052714 tellurium Inorganic materials 0.000 description 9
- PORWMNRCUJJQNO-UHFFFAOYSA-N tellurium atom Chemical compound [Te] PORWMNRCUJJQNO-UHFFFAOYSA-N 0.000 description 9
- 239000000463 material Substances 0.000 description 8
- 238000000034 method Methods 0.000 description 8
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 6
- 238000002425 crystallisation Methods 0.000 description 6
- 230000008025 crystallization Effects 0.000 description 6
- 239000002904 solvent Substances 0.000 description 6
- 230000032258 transport Effects 0.000 description 5
- 238000010521 absorption reaction Methods 0.000 description 3
- 229910052786 argon Inorganic materials 0.000 description 3
- 150000001875 compounds Chemical class 0.000 description 3
- 239000010453 quartz Substances 0.000 description 3
- 230000005855 radiation Effects 0.000 description 3
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 3
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- 229910000925 Cd alloy Inorganic materials 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 125000004429 atom Chemical group 0.000 description 2
- WZGKIRHYWDCEKP-UHFFFAOYSA-N cadmium magnesium Chemical compound [Mg].[Cd] WZGKIRHYWDCEKP-UHFFFAOYSA-N 0.000 description 2
- 229910002092 carbon dioxide Inorganic materials 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- XSOKHXFFCGXDJZ-UHFFFAOYSA-N telluride(2-) Chemical compound [Te-2] XSOKHXFFCGXDJZ-UHFFFAOYSA-N 0.000 description 2
- 229910002058 ternary alloy Inorganic materials 0.000 description 2
- 229910000952 Be alloy Inorganic materials 0.000 description 1
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- 239000000460 chlorine Substances 0.000 description 1
- 229910052801 chlorine Inorganic materials 0.000 description 1
- 150000001805 chlorine compounds Chemical class 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000006378 damage Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 125000005843 halogen group Chemical group 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 230000005012 migration Effects 0.000 description 1
- 238000013508 migration Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 230000006798 recombination Effects 0.000 description 1
- 238000005215 recombination Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000004857 zone melting Methods 0.000 description 1
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
- G02B6/102—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type for infrared and ultraviolet radiation
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C3/00—Glass compositions
- C03C3/32—Non-oxide glass compositions, e.g. binary or ternary halides, sulfides or nitrides of germanium, selenium or tellurium
- C03C3/321—Chalcogenide glasses, e.g. containing S, Se, Te
-
- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B11/00—Single-crystal growth by normal freezing or freezing under temperature gradient, e.g. Bridgman-Stockbarger method
-
- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
- C30B29/10—Inorganic compounds or compositions
- C30B29/46—Sulfur-, selenium- or tellurium-containing compounds
- C30B29/48—AIIBVI compounds wherein A is Zn, Cd or Hg, and B is S, Se or Te
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Crystallography & Structural Chemistry (AREA)
- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Toxicology (AREA)
- Geochemistry & Mineralogy (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- General Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Inorganic Chemistry (AREA)
- Crystals, And After-Treatments Of Crystals (AREA)
Abstract
CADMIUM TELLURIDE COMPENSATED BY
MAGNESIUM OR BERYLLIUM WHICH MAY BE DOPED
AND ITS APPLICATIONS
Abstract of the Disclosure Cadmium telluride forming a single-crystal intrinsic semiconductor having high resistivity contains at least one metal selected from the group comprising beryllium and magnesium having a concentration of less than 5 x 1020 atoms per cm3 as well as a doping agent selected from the group comprising the chloride of cadmium, zinc, magnesium, beryllium and aluminum and is employed in the fabrication of infrared windows or quantum detectors.
MAGNESIUM OR BERYLLIUM WHICH MAY BE DOPED
AND ITS APPLICATIONS
Abstract of the Disclosure Cadmium telluride forming a single-crystal intrinsic semiconductor having high resistivity contains at least one metal selected from the group comprising beryllium and magnesium having a concentration of less than 5 x 1020 atoms per cm3 as well as a doping agent selected from the group comprising the chloride of cadmium, zinc, magnesium, beryllium and aluminum and is employed in the fabrication of infrared windows or quantum detectors.
Description
. -1076~f~0 This inventlon relates to cadmium telluridecompensated with magnesium or wi-th beryllium, said telluride being employed for the purpose of forming infrared windows or quantum detectors. This product may in some cases be doped.
It is known that, in order to employ cadmium telluride as an infrared window or as a quantum detector, it is necessary to make use of material which has high resistivity, that ls, which contains a very low free-carrier concentration.
When windows which are transparent to infrared radiation are employed for high-power C02 lasers, it is essential to ensure that these windows absorb as little radiation as possible : the absorption is directly related to the free-carrier concentratior. which must accordingly be of very low value since even very weak absorption would result in a temperature build-up and in destruction of these windows at the high power levels of modern pulsed carbon-dioxide lasers.
In regard to quantum detectors, for example the solid-state ionization chambers in which a semiconductor crystal is sandwiched between two electrodes, it is necessary to employ a semiconductor having a high specific weight and high resisti~ity in order to ensure that the leakage current is not very high and that electron-hole pairs are formed under the influence of certain radiations such as X- or gamma-rays, for example, thus resulting in a current variation between the electrodes, on condition that the semiconductor is of sufficiently good quality to ensure that the electron-hole pair is not destroyed by recombination at the time of migration through the crystal.
Cadmium telluride can be prepared by crystallization _~
~ ,, , . . . .
,, , , ,, - .
, . . . .
, . :
, i~764~0 in solvent tellurium by the method of zone transport or by the method of depletion of solution. Under these conditions r the material obtained is ~-type ; its concentration of free carriers, namely of cadmium vacancies, is still too high for the applications which are c~ontemplated.
Fræ~lc In an earlier~patent No 73 17261 filed on May 11th, 1973 in the name of C.E.A~, there was given a description which showed how it was possible to compensate for the free-carrier concentration by making use of suitable doping agents, especially chlorine introduced into the crystal-growth bath in the form of cadmium chloride.
The concentration of doping agent in the crystal is ~-~
then of the same order as the vacancy concentration of cadmium to be compensated, namely about 1017 atoms per cm3. This ;~
concentration increases as the production temperature is higher. However, it is an advantage to introduce a lower concentration of doping agents in order to improve certain electron characteristics of the material. For example, it is possible to carry out the crystallization at low temperature, thus reducing the cadmium vacancy concentration and conse~
quently the necessary concentration of doping agent. However, this is not very advantageous from the point of view of growth kinetics by reason of the low crystallization tempera~
ture (low rate of crystallization?.
There is praduced in accordance with the invention a novel material having a base-of cadmium telluride and of another substance which is either magnesium or beryllium, the metallic vacancy concentration of said material being lower than in the case of cadmium telluride alone.
For the applications mentioned in the foregoing, the material in accordance with the invention consists of cadmium ,...... . . . . .
:; .... ' . ' ,, ', ,; ' , ' ::: : . . . .
,:',; , ' ' ' " ' ' ' '' , . :: ' ' ' ' ,:
4~0 telluride compensated by at least one metal selected from the group of beryllium or magnesium, the maximum concentration of said metals being equal to 5 x 102 atoms per cm3. The material in accordance with the invention can also contain at least one doping agent selected from the group consisting of chlorides of cadmium, zinc, magnesium, beryllium and aluminum.
The concentration of doping agents which is necessary in order to complete the compensation process is very much lower than that which is required for compensation of cadmium telluride alone, all other things being equal. In the case of cadmium telluride compensated with magnesium or with beryllium, a low concentration of magnesium or of ~eryllium considerably reduces the metallic vacancy concentra-tion if this ternary compound is prepared in solvent tellurium under conditions similar to those required for Gbtaining the binary compound alone.
The ionic radius of magnesium which is isoelectronic with cadmium is shorter than that of cadmium, thus facilitating the introduction of magnesium into the cadmium telluride lattice. The resultant low free-carrier concentration means that the "solidus" surface which determines the range of existence of the cadmium-magnesium-tellurium ternary compound on the tellurium side in the phase-equilibrium diagram comes close to the plane of the pseudo-binary section of cadmium-tellurium-magnesium-tellurium which is strictly stoichiometric;
a similar result can be obtained when replacing magnesium by beryllium which is also isoelectronic with cadmium, the ionic radius of which is even shorter than that of magnesiumO
In the product in accordance with the invention, the maximum concentration of magnesium or of beryllium is 5 x 102 at/cm3. In the method 6 preparation of this product, _4_ ,, -. ' '. ' .
~76~i0 the solution depletion technique can be employed, the charge being made up of cadmium, magnesium (or beryllium) or of a magnesium-cadmium alloy (or a cadmium-beryllium alloy), of tellurium and of doping agent.
It is also possible to adopt the technique of trans-port from a tellurium zone containing the doping agent and magnesium (or beryllium), the polycrystalline ingot traversed by the solvent zone being in turn constituted by the ternary alloy consisting of cadmium-magnesium-tellurium. This ternary alloy can undergo a preliminary preparation by means of a conventional technique which makes use of a ~ridgman furnace.
In the case in which the solutlon depletion method is employed or in the case of the method of solvent zone transport, the magnesium (or beryllium) can be employed either in the pure state or in the form of an alloy with cadmium ; purification of this alloy can readily be carried ;~
out by zone melting. The doping agent is a halide and more especially a chloride of cadmium, zinc, magnesium, beryllium and in some cases aluminum.
EXAMPLE I
In a first practical example, there is introduced into an internally graphitized quartz vessel a charge composed of :
543 grams of cadmium 942 grams of tellurium 10 grams of magnesium-cadmium alloy containing 70 at ~ Cd 500 mg of cadmium chloride.
The vessel is sealed in an argon vacuum, then intro-duced into a Bridgman furnace of known type.
The vessel is brought to a temperature such that the ,- . .
., .
,.:.' ' , .
.~ .
,' ' .
~6~;0 charge is en-tirely llquld, that is to say at a temperature above 967C. The vessel is then displaced slowly at a rate of 0~3 mm per hour so as to obtain unidirectional crystallization from one end of the vessel and to bring back the excess solvent, namely tellurium, to the other end.
The crystal obtained has a resistivity which is higher than 106 ohms/cm Said crystal is wholly suitable for the fabrication of a nuclear detector, for example, and also an infrared window. The transmission of photons is in the vicinity of lO0 % in the band of 2.5 to 17 microns, which justifies the use of the material as an infrared window.
There is noted a localized mode of infrared absorption at 20 microns which is characteristic of the presence of magnesium in the crystal.
EXAMPLE II
In a second example of crystallization by transport of a tellurium zone, a polycrystalline ingot is formed in a first stage.
To this end, there is introduced into an internally graphitized quartz vessel a charge composed of :
255.2 g of Te 222.5 g of Cd 0.5 g of Mg corresponding to the composition :
C~0.49s~ Mgo.005~ 0-5 which is entirely liquid and at a temperature slightly higher than 1090C. The vessel has a diameter of 25 mm and a length of 1250 mm, is sealed under an argon vacuum, then introduced into a furnace. The charge is brought to a temperature which is higher than 1090C then cooled.
In a second stage, recrysLallization is performed by 107~4~
zone transport in which the polycrystalline ingot obtained in the first stage is withdrawn from its quartz vessel, then introduced into a second vessel. A quantity of 30 g of tellurium to which were added 10 mg of magnesium chloride has previously been placed at the end of said second vessel.
The vessel is sealed in an argon vacuum, whereupon the solvent zone is transferred from one end of the rod to the other under the combined action of the furnace and of a relative displace-ment of the furnace and of the vessel. The growth rate is 0.3 mm/h and the temperature of the furnace is 900C.
::
~' . .
It is known that, in order to employ cadmium telluride as an infrared window or as a quantum detector, it is necessary to make use of material which has high resistivity, that ls, which contains a very low free-carrier concentration.
When windows which are transparent to infrared radiation are employed for high-power C02 lasers, it is essential to ensure that these windows absorb as little radiation as possible : the absorption is directly related to the free-carrier concentratior. which must accordingly be of very low value since even very weak absorption would result in a temperature build-up and in destruction of these windows at the high power levels of modern pulsed carbon-dioxide lasers.
In regard to quantum detectors, for example the solid-state ionization chambers in which a semiconductor crystal is sandwiched between two electrodes, it is necessary to employ a semiconductor having a high specific weight and high resisti~ity in order to ensure that the leakage current is not very high and that electron-hole pairs are formed under the influence of certain radiations such as X- or gamma-rays, for example, thus resulting in a current variation between the electrodes, on condition that the semiconductor is of sufficiently good quality to ensure that the electron-hole pair is not destroyed by recombination at the time of migration through the crystal.
Cadmium telluride can be prepared by crystallization _~
~ ,, , . . . .
,, , , ,, - .
, . . . .
, . :
, i~764~0 in solvent tellurium by the method of zone transport or by the method of depletion of solution. Under these conditions r the material obtained is ~-type ; its concentration of free carriers, namely of cadmium vacancies, is still too high for the applications which are c~ontemplated.
Fræ~lc In an earlier~patent No 73 17261 filed on May 11th, 1973 in the name of C.E.A~, there was given a description which showed how it was possible to compensate for the free-carrier concentration by making use of suitable doping agents, especially chlorine introduced into the crystal-growth bath in the form of cadmium chloride.
The concentration of doping agent in the crystal is ~-~
then of the same order as the vacancy concentration of cadmium to be compensated, namely about 1017 atoms per cm3. This ;~
concentration increases as the production temperature is higher. However, it is an advantage to introduce a lower concentration of doping agents in order to improve certain electron characteristics of the material. For example, it is possible to carry out the crystallization at low temperature, thus reducing the cadmium vacancy concentration and conse~
quently the necessary concentration of doping agent. However, this is not very advantageous from the point of view of growth kinetics by reason of the low crystallization tempera~
ture (low rate of crystallization?.
There is praduced in accordance with the invention a novel material having a base-of cadmium telluride and of another substance which is either magnesium or beryllium, the metallic vacancy concentration of said material being lower than in the case of cadmium telluride alone.
For the applications mentioned in the foregoing, the material in accordance with the invention consists of cadmium ,...... . . . . .
:; .... ' . ' ,, ', ,; ' , ' ::: : . . . .
,:',; , ' ' ' " ' ' ' '' , . :: ' ' ' ' ,:
4~0 telluride compensated by at least one metal selected from the group of beryllium or magnesium, the maximum concentration of said metals being equal to 5 x 102 atoms per cm3. The material in accordance with the invention can also contain at least one doping agent selected from the group consisting of chlorides of cadmium, zinc, magnesium, beryllium and aluminum.
The concentration of doping agents which is necessary in order to complete the compensation process is very much lower than that which is required for compensation of cadmium telluride alone, all other things being equal. In the case of cadmium telluride compensated with magnesium or with beryllium, a low concentration of magnesium or of ~eryllium considerably reduces the metallic vacancy concentra-tion if this ternary compound is prepared in solvent tellurium under conditions similar to those required for Gbtaining the binary compound alone.
The ionic radius of magnesium which is isoelectronic with cadmium is shorter than that of cadmium, thus facilitating the introduction of magnesium into the cadmium telluride lattice. The resultant low free-carrier concentration means that the "solidus" surface which determines the range of existence of the cadmium-magnesium-tellurium ternary compound on the tellurium side in the phase-equilibrium diagram comes close to the plane of the pseudo-binary section of cadmium-tellurium-magnesium-tellurium which is strictly stoichiometric;
a similar result can be obtained when replacing magnesium by beryllium which is also isoelectronic with cadmium, the ionic radius of which is even shorter than that of magnesiumO
In the product in accordance with the invention, the maximum concentration of magnesium or of beryllium is 5 x 102 at/cm3. In the method 6 preparation of this product, _4_ ,, -. ' '. ' .
~76~i0 the solution depletion technique can be employed, the charge being made up of cadmium, magnesium (or beryllium) or of a magnesium-cadmium alloy (or a cadmium-beryllium alloy), of tellurium and of doping agent.
It is also possible to adopt the technique of trans-port from a tellurium zone containing the doping agent and magnesium (or beryllium), the polycrystalline ingot traversed by the solvent zone being in turn constituted by the ternary alloy consisting of cadmium-magnesium-tellurium. This ternary alloy can undergo a preliminary preparation by means of a conventional technique which makes use of a ~ridgman furnace.
In the case in which the solutlon depletion method is employed or in the case of the method of solvent zone transport, the magnesium (or beryllium) can be employed either in the pure state or in the form of an alloy with cadmium ; purification of this alloy can readily be carried ;~
out by zone melting. The doping agent is a halide and more especially a chloride of cadmium, zinc, magnesium, beryllium and in some cases aluminum.
EXAMPLE I
In a first practical example, there is introduced into an internally graphitized quartz vessel a charge composed of :
543 grams of cadmium 942 grams of tellurium 10 grams of magnesium-cadmium alloy containing 70 at ~ Cd 500 mg of cadmium chloride.
The vessel is sealed in an argon vacuum, then intro-duced into a Bridgman furnace of known type.
The vessel is brought to a temperature such that the ,- . .
., .
,.:.' ' , .
.~ .
,' ' .
~6~;0 charge is en-tirely llquld, that is to say at a temperature above 967C. The vessel is then displaced slowly at a rate of 0~3 mm per hour so as to obtain unidirectional crystallization from one end of the vessel and to bring back the excess solvent, namely tellurium, to the other end.
The crystal obtained has a resistivity which is higher than 106 ohms/cm Said crystal is wholly suitable for the fabrication of a nuclear detector, for example, and also an infrared window. The transmission of photons is in the vicinity of lO0 % in the band of 2.5 to 17 microns, which justifies the use of the material as an infrared window.
There is noted a localized mode of infrared absorption at 20 microns which is characteristic of the presence of magnesium in the crystal.
EXAMPLE II
In a second example of crystallization by transport of a tellurium zone, a polycrystalline ingot is formed in a first stage.
To this end, there is introduced into an internally graphitized quartz vessel a charge composed of :
255.2 g of Te 222.5 g of Cd 0.5 g of Mg corresponding to the composition :
C~0.49s~ Mgo.005~ 0-5 which is entirely liquid and at a temperature slightly higher than 1090C. The vessel has a diameter of 25 mm and a length of 1250 mm, is sealed under an argon vacuum, then introduced into a furnace. The charge is brought to a temperature which is higher than 1090C then cooled.
In a second stage, recrysLallization is performed by 107~4~
zone transport in which the polycrystalline ingot obtained in the first stage is withdrawn from its quartz vessel, then introduced into a second vessel. A quantity of 30 g of tellurium to which were added 10 mg of magnesium chloride has previously been placed at the end of said second vessel.
The vessel is sealed in an argon vacuum, whereupon the solvent zone is transferred from one end of the rod to the other under the combined action of the furnace and of a relative displace-ment of the furnace and of the vessel. The growth rate is 0.3 mm/h and the temperature of the furnace is 900C.
::
~' . .
Claims (5)
1. A quantum detector of cadmium telluride com-prising beryllium or magnesium in a concentration less than or equal to 1017 atoms per cm3.
2. A quantum detector according to Claim 1, further comprising a doping agent selected from cadmium chloride, zinc chloride, magnesium chloride, beryllium chloride or aluminum chloride.
3. A nuclear detector comprising a nuclear detector incorporating therein a quantum detector of cadmium telluride comprising beryllium or magnesium in a concentration less than or equal to 1017 atoms per cm3 and a doping agent selected from cadmium chloride, zinc chloride, magnesium chloride, beryllium chloride or aluminum chloride, said quantum detector having a resistivity higher than 106 ohms/cm.
4. An infrared window comprising a window incorpo-rating therein a quantum detector of cadmium telluride com-prising beryllium or magnesium in a concentration less than or equal to 1017 atoms per cm3 and a doping agent selected from cadmium chloride, zinc chloride, magnesium chloride, beryllium chloride or aluminum chloride, said quantum detector having a resistivity higher than 106 ohms/cm.
5. A single crystal intrinsic semiconductor com-prising a semiconductor crystal incorporating therein a quantum detector of cadmium telluride comprising beryllium or magnesium in a concentration less than or equal to 1017 atoms per cm3 and a doping agent selected from cadmium chloride, zinc chloride, magnesium chloride, beryllium chloride or aluminum chloride, said quantum detector having a resistivity higher than 106 ohms/cm.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR7519262A FR2314759A1 (en) | 1975-06-19 | 1975-06-19 | CADMIUM TELLURIDE COMPENSATES WITH MAGNESIUM OR BERYLLIUM POSSIBLY DOPED AND ITS APPLICATIONS |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1076460A true CA1076460A (en) | 1980-04-29 |
Family
ID=9156769
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA254,751A Expired CA1076460A (en) | 1975-06-19 | 1976-06-14 | Cadmium telluride compensated with magnesium or beryllium |
Country Status (7)
| Country | Link |
|---|---|
| JP (1) | JPS522896A (en) |
| BE (1) | BE842720A (en) |
| CA (1) | CA1076460A (en) |
| DE (1) | DE2626841A1 (en) |
| FR (1) | FR2314759A1 (en) |
| GB (1) | GB1498374A (en) |
| NL (1) | NL7606595A (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0261647A3 (en) * | 1986-09-26 | 1989-08-16 | Nippon Mining Company Limited | High resistivity cdte crystal and process for producing the same |
| FR2703696B1 (en) * | 1993-04-08 | 1995-06-09 | Eurorad 2 6 Sarl | PROCESS FOR OBTAINING A DOPED CRYSTALLINE MATERIAL BASED ON TELLURE AND CADMIUM AND A DETECTOR COMPRISING SUCH A MATERIAL. |
| GB2308356A (en) * | 1995-12-19 | 1997-06-25 | Heatvision Technics Corp | Processing complex semiconductors |
| FR2836931B1 (en) | 2002-03-05 | 2004-04-30 | Eurorad 2 6 | PROCESS FOR PRODUCING HIGH RESISTIVITY SEMICONDUCTOR CdXTe CRYSTALS AND RESULTING CRYSTALLINE MATERIAL |
-
1975
- 1975-06-19 FR FR7519262A patent/FR2314759A1/en active Granted
-
1976
- 1976-06-04 GB GB23309/76A patent/GB1498374A/en not_active Expired
- 1976-06-09 BE BE167728A patent/BE842720A/en unknown
- 1976-06-14 CA CA254,751A patent/CA1076460A/en not_active Expired
- 1976-06-15 DE DE19762626841 patent/DE2626841A1/en not_active Withdrawn
- 1976-06-17 NL NL7606595A patent/NL7606595A/en not_active Application Discontinuation
- 1976-06-18 JP JP51072104A patent/JPS522896A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| NL7606595A (en) | 1976-12-21 |
| GB1498374A (en) | 1978-01-18 |
| DE2626841A1 (en) | 1976-12-30 |
| BE842720A (en) | 1976-10-01 |
| FR2314759A1 (en) | 1977-01-14 |
| FR2314759B1 (en) | 1980-05-09 |
| JPS522896A (en) | 1977-01-10 |
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