US3104365A - Photoconductive device and methods of making same - Google Patents
Photoconductive device and methods of making same Download PDFInfo
- Publication number
- US3104365A US3104365A US509697A US50969755A US3104365A US 3104365 A US3104365 A US 3104365A US 509697 A US509697 A US 509697A US 50969755 A US50969755 A US 50969755A US 3104365 A US3104365 A US 3104365A
- Authority
- US
- United States
- Prior art keywords
- crystal
- crystals
- ray
- cadmium sulfide
- sulfide
- 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 - Lifetime
Links
- 238000000034 method Methods 0.000 title claims description 28
- 239000013078 crystal Substances 0.000 claims description 68
- 230000004044 response Effects 0.000 claims description 26
- 229910052980 cadmium sulfide Inorganic materials 0.000 claims description 24
- WUPHOULIZUERAE-UHFFFAOYSA-N 3-(oxolan-2-yl)propanoic acid Chemical compound OC(=O)CCC1CCCO1 WUPHOULIZUERAE-UHFFFAOYSA-N 0.000 claims description 23
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical class [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 7
- 239000001257 hydrogen Substances 0.000 claims description 6
- 229910052739 hydrogen Inorganic materials 0.000 claims description 6
- 239000002245 particle Substances 0.000 claims description 6
- 238000010438 heat treatment Methods 0.000 claims description 5
- 239000007789 gas Substances 0.000 claims description 3
- 239000003638 chemical reducing agent Substances 0.000 claims description 2
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 claims 2
- 230000005855 radiation Effects 0.000 description 19
- BDOSMKKIYDKNTQ-UHFFFAOYSA-N cadmium atom Chemical compound [Cd] BDOSMKKIYDKNTQ-UHFFFAOYSA-N 0.000 description 9
- 239000000463 material Substances 0.000 description 9
- 229910052793 cadmium Inorganic materials 0.000 description 8
- 238000005259 measurement Methods 0.000 description 7
- 150000001875 compounds Chemical class 0.000 description 6
- RWSOTUBLDIXVET-UHFFFAOYSA-N Dihydrogen sulfide Chemical compound S RWSOTUBLDIXVET-UHFFFAOYSA-N 0.000 description 5
- 229910000037 hydrogen sulfide Inorganic materials 0.000 description 5
- 230000008569 process Effects 0.000 description 5
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 4
- 238000010521 absorption reaction Methods 0.000 description 4
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 4
- 229910052753 mercury Inorganic materials 0.000 description 4
- 150000004763 sulfides Chemical class 0.000 description 4
- 229910052725 zinc Inorganic materials 0.000 description 4
- 239000011701 zinc Substances 0.000 description 4
- 230000008859 change Effects 0.000 description 3
- 238000012552 review Methods 0.000 description 3
- 230000035945 sensitivity Effects 0.000 description 3
- 239000012808 vapor phase Substances 0.000 description 3
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 2
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 2
- 238000000862 absorption spectrum Methods 0.000 description 2
- 238000000137 annealing Methods 0.000 description 2
- 239000007772 electrode material Substances 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 150000002739 metals Chemical class 0.000 description 2
- 150000003346 selenoethers Chemical class 0.000 description 2
- 229910052709 silver Inorganic materials 0.000 description 2
- 239000004332 silver Substances 0.000 description 2
- 238000010583 slow cooling Methods 0.000 description 2
- 238000006467 substitution reaction Methods 0.000 description 2
- 150000004772 tellurides Chemical class 0.000 description 2
- 229910052718 tin Inorganic materials 0.000 description 2
- 206010034972 Photosensitivity reaction Diseases 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000001447 compensatory effect Effects 0.000 description 1
- 238000009833 condensation Methods 0.000 description 1
- 230000005494 condensation Effects 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000012937 correction Methods 0.000 description 1
- 230000002596 correlated effect Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000000151 deposition Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000036211 photosensitivity Effects 0.000 description 1
- 229910052573 porcelain Inorganic materials 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 230000009897 systematic effect Effects 0.000 description 1
- 230000008016 vaporization Effects 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/08—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof in which radiation controls flow of current through the device, e.g. photoresistors
Definitions
- crystals of cadmium sulfide and like compounds may be grown by controlled condensation from the vapor phase, a full disclosure of one such method being given by Frerichs in the October 1, 1947, issue of Physical Review, volume 72, No. 7, at pages 594-601.
- the presentinvention provides basic improvements on these prior vapor phase crystal growth processes, the crystal growth processes of the invention being particularly advantageous in requiring less precise control of temperature during the growing operation and in affording better control of crystal size and thickness than prior processes such as that of Frerichs.
- cadmium sulfide and similar com? pounds including the sulfides, selenides, tellurides and oxides of the metals zinc, cadmium and mercury, are photosensitive to X-ray radiation, their conductivity varying with intensity of the incident radiation.
- Such materials preferably in the form of large single crystals or nongranulate coalescent layers, therefore may be used for the detection and measurement of X-ray radiation.
- the X-ray sensitive crystal or layer have X-ray response characteristics substantially similar to those of the conventional ionization chamber type X-ray sensing unit, so as to enable direct substitution of the crystal or layer into the measuring circuits commonly used with these ionization chamber instruments.
- ionization chamber X-ray units normally present an effective resistance which is inversely proportional to the intensity of the incident radiation, i.e., its response is substantially linear with varying intensity of radiation of constant wavelength. Ionization current also varies with radiation wavelength and, accordingly, with X-ray voltage.
- Cadmium sulfide and like photocrystals as heretofore produced do not possess response characteristics matching the ionization chamber as is necessary to permit their use interchangeably therewith. iln general, photoconductivity in such crystals does not increase proportionally to the intensity of incident radiation, but rather increases more slowly and in the limiting condition increases proportionally with the square root of the absorbed energy. While some few crystals produced by prior methods do have this required linearity of response, such crystals almost invariably are relatively insensitive and do not provide readily measured resistance changes. Moreover, in few if any such prior crystals does the photoconductance 3,104,365 Patented Sept. 17, 1963 vary with radiation voltage and wavelength in the same or similar manner to the air ionization elements.
- crystals of cadmium sulfide and other compounds as listed above may be produced and their response characteristics modified to provide the desired correspondence with ionization cham her response, so as to afford full interchangeability therewith and accurate X-ray dosage measurements in units.
- Crystal treatment according to the invention permits systematic linearizing of response of high sensitivity crystals, with any unavoidable loss in sensitivity incident thereto being very small and no greater than absolutely necessary.
- a cadmium sulfide or like crystal grown and its response characteristics modified by the methods of the invention has the following advantages over the conventional ionization chamber unit: (1)
- the voltage applied to the crystal may be very small particularly if maximum sensitivity is not required, a few volts as provided by a tube plate or heater battery usually is adequate; (2)
- the photoconductance currents normally are several times higher than ionization currents as usually obtained, hence only common instruments are required for current measurement; and (3)
- the small size of the crystal makes its use as a radiation dosimeter possible where the size of the conventional ionization chamber is an obstacle, thus permitting use of the crystal type dosimeter within the human body and also in making spot measurements of X-ray intensity.
- Another object of the invention is the provision of novel methods for modifying the response characteristics of cadmium sulfide and like crystals so as to match those of the conventional ionization chamber units for interchangeability of use therewith particularly in X-ray measurement.
- the Frerichs article cited above discloses a method for growing single crystals of cadmium sulfide in steps of placing a quantity of cadmium metal in a small porcelain boat and heating the same within an elongated closed growing tube, which may be of quartz, to a temperature of about 800 to 1000 C.
- Aslow stream of hydrogen gas is passed through the tube and over the boat therein by a hydrogen supply conduit opening into one end of the growing tube, suitable exhaust means being provided at the other end.
- Cadmium vapor rising from the boat is entrained in the hydrogen flow and moves with it to a point adjacent the downstream end of the boat, where it mingles with hydrogen sulfide introduced there by a second supply conduit means.
- a reaction then occurs by which cadmium sulfide vapor is condensed in crystalline form within the growing tube.
- crystals of very pure photoconductive cadmium sultide are said to be obtained, with good uniformity of re- 'just described.
- thisand like crystal quires that slightly higher temperatures, be reached during the growing process, but the procedural steps followed and apparatus .used maybe otherwise identical to those a
- the growing temperature, while higher, is much less critical to satisfiactory crystal growth,;thus significantly improving the crystal yield- This greater permissible variation in temperature affords better control of the size and thickness of the crystals grown.
- the necessary change in crystal response characteristics to obtain this desiredcorrelation may in accordance with one method of the invention be obtained by exposing the crystals to high energy corpuscular radiation, as for example alpha particle bombardment.
- the extent of the change in response oharacteristicsdepends on the number of particles absorbed by the crystal, :andit therefiore may be precisely controlled by careful selection of the intensity and duration of irradiation.
- the crystals should be irradiated with approximately 10 alphaparticles per sq. cm.
- a second method effective to linearize crystal response is to leave the crystal for an extended period of time exposed to relatively high temperature.
- the effects on the crystal may be controlled by varying the length of time heat treatment is continued and also by varying the Highly sensitive cadmium sulfide may be X-ray range after a short annealing at about 500 C., followed by slow cooling.
- the present invention further comprehends methods I for compensating the X-ray Wavelength dependency of cient.
- This dilierence causes the crystal photocurrent change to be not directly proportional, to the value as the X-ray voltage and wavelength are varied.
- these deviations may be substantially corrected'by placing over the crystal, in the path of the X-ray beam, an. absorbing layer or filter whose thickness and material is dependent on the nature of the deviation of photocurrent fromv the 7 value.
- a filter material whose absorption spectrum for X-rays is exactly the same as or similar to the absorption spectrum of the crystal should be used. For example, if the crystal is of cadmium sulfide the filter should be either of cadmium, tin or silver.
- the crystal electrodes may in accordance with the invention be utilized as such a compensatory filter by proper selection of electrode material and thickness on at least the cathode side of the crystal.
- the correction or compensation of wavelength dependency is easier if crystals absorb only a small portion of the incident energy. It therefore is desirable to make the crystals as thin as possible, and in practice relatively thin large area crystals' are preferred.
- the method of growing large single crystals of cadmium sulfide and linearizing response characteristics: thereof comprising the steps of heating powdered cadmium sulfide to produce a vapor thereof, introducing hydrogen and hydrogen sulfide gases to serve as a reducing agent and as a vehicle for carrying the vapor to a region of lower temperature thereby causing the vapor to condense and form as a sublimate large single crystals of cadmium sulfide, and, then exposing said single crystals to highenergy particle irradiation for linearizing the response characteristics of said crystals.
- cadmium and mercury which includes the step of su jecting the crystals to radiation by alpha particles.
- a photosensitive element particularly for X-ray dosimeter use comprising a single crystal of a radiant energy sensitive compound selected from the group consisting of the sulfides of zinc, cadmium and mercury, having on at least one side thereof an electrode of a material having X-ray absorption characteristics similar to the absorption characteristics of'the crystal such that crystal photoconducance responsive to X-ray irradiation is correlated to wavelength of the incident radiation in predetermined desired manner.
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Computer Hardware Design (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Power Engineering (AREA)
- Electromagnetism (AREA)
- Manufacturing & Machinery (AREA)
- Light Receiving Elements (AREA)
- Photoreceptors In Electrophotography (AREA)
Description
United States Patent This invention relates to improvements in methods for production and treatment of photosensitive materials and more specifically to new and improved methods for producing large mono-crystals of cadmium sulfide and like photosensitive compounds and for treating crystals and coalescent layers of such compounds to obtain predetermined desired response characteristics particularly to X- ray radiation, and to articles thus produced.
It has heretofore been disclosed that crystals of cadmium sulfide and like compounds may be grown by controlled condensation from the vapor phase, a full disclosure of one such method being given by Frerichs in the October 1, 1947, issue of Physical Review, volume 72, No. 7, at pages 594-601. In one important aspect, the presentinvention provides basic improvements on these prior vapor phase crystal growth processes, the crystal growth processes of the invention being particularly advantageous in requiring less precise control of temperature during the growing operation and in affording better control of crystal size and thickness than prior processes such as that of Frerichs.
It is known that cadmium sulfide and similar com? pounds, including the sulfides, selenides, tellurides and oxides of the metals zinc, cadmium and mercury, are photosensitive to X-ray radiation, their conductivity varying with intensity of the incident radiation. Such materials, preferably in the form of large single crystals or nongranulate coalescent layers, therefore may be used for the detection and measurement of X-ray radiation. For maximum ease and extent of application it is highly desirable that the X-ray sensitive crystal or layer have X-ray response characteristics substantially similar to those of the conventional ionization chamber type X-ray sensing unit, so as to enable direct substitution of the crystal or layer into the measuring circuits commonly used with these ionization chamber instruments. This would permit use of CdS and like photoelements interchangeably with ionization chamber elements in a single measuring circuit with little or no modification thereof, but such interchangeability has heretofore been impossible because of the basically different response characteristics of ionization chamber and photoconductive type sensitive elements.
ionization chamber X-ray units normally present an effective resistance which is inversely proportional to the intensity of the incident radiation, i.e., its response is substantially linear with varying intensity of radiation of constant wavelength. Ionization current also varies with radiation wavelength and, accordingly, with X-ray voltage.
Cadmium sulfide and like photocrystals as heretofore produced do not possess response characteristics matching the ionization chamber as is necessary to permit their use interchangeably therewith. iln general, photoconductivity in such crystals does not increase proportionally to the intensity of incident radiation, but rather increases more slowly and in the limiting condition increases proportionally with the square root of the absorbed energy. While some few crystals produced by prior methods do have this required linearity of response, such crystals almost invariably are relatively insensitive and do not provide readily measured resistance changes. Moreover, in few if any such prior crystals does the photoconductance 3,104,365 Patented Sept. 17, 1963 vary with radiation voltage and wavelength in the same or similar manner to the air ionization elements.
In accordance with the invention, crystals of cadmium sulfide and other compounds as listed above may be produced and their response characteristics modified to provide the desired correspondence with ionization cham her response, so as to afford full interchangeability therewith and accurate X-ray dosage measurements in units. Crystal treatment according to the invention permits systematic linearizing of response of high sensitivity crystals, with any unavoidable loss in sensitivity incident thereto being very small and no greater than absolutely necessary.
For X-ray measurement, a cadmium sulfide or like crystal grown and its response characteristics modified by the methods of the invention has the following advantages over the conventional ionization chamber unit: (1) The voltage applied to the crystal may be very small particularly if maximum sensitivity is not required, a few volts as provided by a tube plate or heater battery usually is adequate; (2) The photoconductance currents normally are several times higher than ionization currents as usually obtained, hence only common instruments are required for current measurement; and (3) The small size of the crystal makes its use as a radiation dosimeter possible where the size of the conventional ionization chamber is an obstacle, thus permitting use of the crystal type dosimeter within the human body and also in making spot measurements of X-ray intensity.
Accordingly, it is a primary object of the invention to provide new and improved methods for producing and modifying the response characteristics of radiant energy sensitive materials including the sulfides, selenides, tellurides and oxides of the metals zinc, cadmium and mercury, and to novel articles as produced by these methods.
It is also an important object of the invention to provide novel methods for producing large single crystals of cadmium sulfide and like radiant energy sensitive materials.
Another object of the invention is the provision of novel methods for modifying the response characteristics of cadmium sulfide and like crystals so as to match those of the conventional ionization chamber units for interchangeability of use therewith particularly in X-ray measurement.
It is a further object of the invention to provide new and improved methods for systematically linearizing the response of cadmium sulfide and like crystals to X-ray irradiation and to obtain predetermined desired correspondence of response with varying X-ray voltage and wavelength.
These and other objects, features and advantages of the invention will become more fully apparent by reference to the appended claims and the following detailed description.
The Frerichs article cited above discloses a method for growing single crystals of cadmium sulfide in steps of placing a quantity of cadmium metal in a small porcelain boat and heating the same within an elongated closed growing tube, which may be of quartz, to a temperature of about 800 to 1000 C. Aslow stream of hydrogen gas is passed through the tube and over the boat therein by a hydrogen supply conduit opening into one end of the growing tube, suitable exhaust means being provided at the other end. Cadmium vapor rising from the boat is entrained in the hydrogen flow and moves with it to a point adjacent the downstream end of the boat, where it mingles with hydrogen sulfide introduced there by a second supply conduit means. A reaction then occurs by which cadmium sulfide vapor is condensed in crystalline form within the growing tube. By slowly cooling down, with the hydrogen and hydrogen sulfide gases still flowing, crystals of very pure photoconductive cadmium sultide are said to be obtained, with good uniformity of re- 'just described.-
' temperature. I
produced with the desired linearityof response in the spouse characteristics from crystal to crystal. and from batch to batch. r
In accordance with the invention, thisand like crystal quires that slightly higher temperatures, be reached during the growing process, but the procedural steps followed and apparatus .used maybe otherwise identical to those a In the crystal growing procedures of the invention the growing temperature, while higher, is much less critical to satisfiactory crystal growth,;thus significantly improving the crystal yield- This greater permissible variation in temperature affords better control of the size and thickness of the crystals grown.
. in-g material in the prior processes. This substitution revery high photosen-sitivity to visible radiation and accordingly are well adapted to use as photoelements' of general utility. They also are highly photoconductive to X-ray.
irradiation, though as initially produced they do not possess the desired correlation with ionization chamber response characteristics as explained in the foregoing.
The necessary change in crystal response characteristics to obtain this desiredcorrelation may in accordance with one method of the invention be obtained by exposing the crystals to high energy corpuscular radiation, as for example alpha particle bombardment. The extent of the change in response oharacteristicsdepends on the number of particles absorbed by the crystal, :andit therefiore may be precisely controlled by careful selection of the intensity and duration of irradiation. For example, to produce cadmium sulfide crystals having the desired linearity of response to X-rays in medium voltage range and of common intensities, the crystals should be irradiated with approximately 10 alphaparticles per sq. cm. A second method effective to linearize crystal response is to leave the crystal for an extended period of time exposed to relatively high temperature. The effects on the crystal may be controlled by varying the length of time heat treatment is continued and also by varying the Highly sensitive cadmium sulfide may be X-ray range after a short annealing at about 500 C., followed by slow cooling.
The above-described methods for linearizing crystal response characteristics relate not only to theiruse in X-ray measurement, but also are useful generally for 7 radiation of other types and particularly quantum radiation and corpuscular radiation.
- The present invention further comprehends methods I for compensating the X-ray Wavelength dependency of cient. This dilierence causes the crystal photocurrent change to be not directly proportional, to the value as the X-ray voltage and wavelength are varied. According to the invention, these deviations may be substantially corrected'by placing over the crystal, in the path of the X-ray beam, an. absorbing layer or filter whose thickness and material is dependent on the nature of the deviation of photocurrent fromv the 7 value. Preferably, a filter material whose absorption spectrum for X-rays is exactly the same as or similar to the absorption spectrum of the crystal should be used. For example, if the crystal is of cadmium sulfide the filter should be either of cadmium, tin or silver. j
The crystal electrodes may in accordance with the invention be utilized as such a compensatory filter by proper selection of electrode material and thickness on at least the cathode side of the crystal.
The correction or compensation of wavelength dependency is easier if crystals absorb only a small portion of the incident energy. It therefore is desirable to make the crystals as thin as possible, and in practice relatively thin large area crystals' are preferred.
The'invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are thereforeto be considered in all respects as illustrative and not restric tive, the scope of the invention being indicated by the appended claims rather than by the foregoing'description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to bet embraced therein.
What is claimed and desired to be secured by United States Letters Patent is:
1; The method of growing large single crystals of cadmium sulfide and linearizing response characteristics: thereof comprising the steps of heating powdered cadmium sulfide to produce a vapor thereof, introducing hydrogen and hydrogen sulfide gases to serve as a reducing agent and as a vehicle for carrying the vapor to a region of lower temperature thereby causing the vapor to condense and form as a sublimate large single crystals of cadmium sulfide, and, then exposing said single crystals to highenergy particle irradiation for linearizing the response characteristics of said crystals.
2. In the method of growing cadmium sulfide monocrystals which include the steps of vaporizing cadmium sulfide in a hydrogen atmosphere and introducing into the vapor thus produced hydrogen sulfide, transferring the vapor mixed with the hydrogen sulfide along a confined path to a region of lower temperature whereby cadmium sulfide condenses from the vapor phase in monocrystalselected from the group consisting of -the sulfides of Zinc,
cadmium and mercury, which includes the step of su jecting the crystals to radiation by alpha particles.
4. A photosensitive element particularly for X-ray dosimeter use comprising a single crystal of a radiant energy sensitive compound selected from the group consisting of the sulfides of zinc, cadmium and mercury, having on at least one side thereof an electrode of a material having X-ray absorption characteristics similar to the absorption characteristics of'the crystal such that crystal photoconducance responsive to X-ray irradiation is correlated to wavelength of the incident radiation in predetermined desired manner. i
5. The photoelement defined in claim 4 wherein the radiant energy sensitive compound is cadmium sulfide and the electrode material is selected from the group consisting of cadmium, tin and silver.
' 6. The method defined in claim 2 including the further step of annealing the crystals grown by heating the crystals to a 'temperaure of the order'of 500 C., followed by slow cooling to linearize the crystal response.
7. The method defined in claim Zincluding the further step of subjecting said grown crystal to radiation by alpha particles.
8. The method defined in claim 7 including the-step of depositing on at least one side of said grown crystal an electrode of a material having X-ray absorption characteristics similar to the absorption characteristics of said crystal. V
(References on following page) References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES M61101: Comprehensive Treatise on Inorganic and Theoretical Chemistry, vol. 4, 1923, pp. 589 and 6 02. 1923 Frerichs: Physical Review, volume 72, No. 7, 1947, 1 1. Thomson Apr. 3, 1923 5 594 601 May 1923 Hofstadter: Physical Review, volume 72, No. 7, 1947, Ca-Skhll May 13, 1930 pp. 1120H2L Andres 1936 Lappand Andrews: Nuclear Radiation Physics, 1948, Betterton et a1 Mar. 31, 1936 3Q2 3 Shockley Jan- 19 1954 0 Glasstone: Principles of Nuclear Reactor Engineering Ravich June 16, 1959 (1st edition 1955), pp. 66 and 67.
Claims (1)
1. THE METHOD OF GROWING LARGE SINGLE CRYSTALS OF CADMINUM SULFIDE AND LINEARIZING RESPONSE CHARACTERISTICS THEREOF COMPRISING THE STEPS OF HEATING POWDERED CADMIUM SULFIDE TO PRODUCE A VAPOR THEREOF, INTRODUCING HYDROGEN AND HYDROGE SULFIDE GASES TO SERVE AS A REDUCING AGENT AND AS A VEHICLE FOR CARRYING THE VAPOR TO A REGION OF LOWER TEMPERATURE THEREBY CAUSING THE VAPOR TO CONDENSE AND FORM AS A SUBLIMATE LARGE SINGLE CRYSTALS OF CADMIUM SULFIDE, AND THEN EXPOSING SAID SINGLE CRYSTALS TO HIGH ENERGY PARTICLE IRRADIATION FOR LINEARIZING THE RESPONSE CHARACTERISTICS OF SAID CRYSTALS.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE3104365X | 1949-07-08 |
Publications (1)
Publication Number | Publication Date |
---|---|
US3104365A true US3104365A (en) | 1963-09-17 |
Family
ID=8086806
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US509697A Expired - Lifetime US3104365A (en) | 1949-07-08 | 1955-05-19 | Photoconductive device and methods of making same |
Country Status (1)
Country | Link |
---|---|
US (1) | US3104365A (en) |
Citations (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US1446720A (en) * | 1920-01-08 | 1923-02-27 | Frederick R Parker | Process of treating electrical resistances to stabilize their resistance |
US1450464A (en) * | 1920-07-26 | 1923-04-03 | Genneral Electric Company | Crystal formation |
US1456532A (en) * | 1916-03-07 | 1923-05-29 | Brown Fay C Luff | Selenium crystals and method of preparing the same |
US1758741A (en) * | 1926-12-17 | 1930-05-13 | Earl C Gaskill | Process for making zinc sulphide |
US2027413A (en) * | 1933-01-31 | 1936-01-14 | Mallory & Co Inc P R | Method of making electrical resistance elements |
US2035453A (en) * | 1932-07-29 | 1936-03-31 | American Smelting Refining | Treating impure antimony trioxide |
US2666814A (en) * | 1949-04-27 | 1954-01-19 | Bell Telephone Labor Inc | Semiconductor translating device |
US2890939A (en) * | 1953-01-07 | 1959-06-16 | Hupp Corp | Crystal growing procedures |
-
1955
- 1955-05-19 US US509697A patent/US3104365A/en not_active Expired - Lifetime
Patent Citations (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US1456532A (en) * | 1916-03-07 | 1923-05-29 | Brown Fay C Luff | Selenium crystals and method of preparing the same |
US1446720A (en) * | 1920-01-08 | 1923-02-27 | Frederick R Parker | Process of treating electrical resistances to stabilize their resistance |
US1450464A (en) * | 1920-07-26 | 1923-04-03 | Genneral Electric Company | Crystal formation |
US1758741A (en) * | 1926-12-17 | 1930-05-13 | Earl C Gaskill | Process for making zinc sulphide |
US2035453A (en) * | 1932-07-29 | 1936-03-31 | American Smelting Refining | Treating impure antimony trioxide |
US2027413A (en) * | 1933-01-31 | 1936-01-14 | Mallory & Co Inc P R | Method of making electrical resistance elements |
US2666814A (en) * | 1949-04-27 | 1954-01-19 | Bell Telephone Labor Inc | Semiconductor translating device |
US2890939A (en) * | 1953-01-07 | 1959-06-16 | Hupp Corp | Crystal growing procedures |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
CN110016646B (en) | Preparation method of lead-based halogen perovskite film for high-energy ray detection | |
Ponpon et al. | Preliminary characterization of PbI2 polycrystalline layers deposited from solution for nuclear detector applications | |
Bennett et al. | Characterization of polycrystalline TlBr films for radiographic detectors | |
Horowitz et al. | Elimination of the residual signal in LiF: Cu, Mg, P | |
US3104365A (en) | Photoconductive device and methods of making same | |
Sadeghi et al. | Synthesis and dosimetry features of novel sensitive thermoluminescent phosphor of LiF doped with Mg and Dy impurities | |
Sahare et al. | K2Ca2 (SO4) 3 for thermoluminescence dosimetry of a high-temperature environment | |
Imran et al. | Crystallization kinetics and optical band gap studies of Se96In4 glass before and after slow neutron irradiation | |
Reynolds et al. | Phase Equilibria in the Zinc‐Tellurium System | |
Härkönen et al. | Particle detectors made of high-resistivity Czochralski silicon | |
Nuraeni et al. | Preliminary studies of thermoluminescence dosimeter (TLD) CaSO4: Dy synthesis | |
Misra et al. | Photocrystallization in amorphous thin films of Se100− xTex | |
Bethge | Detection and profiling of light elements in different condensed matter matrices | |
Miyake | Measurement of the Partial Pressure of Cesium over Cesium Antimonides | |
Karimov et al. | Peculiarities of influence of radiation defects on photoconductivity of silicon irradiated by fast neutrons | |
Abdel-Malik et al. | Electric and photoelectric investigations of?? nickel phthalocyanine thin films | |
Ceasar et al. | Photoacoustic and xerographic investigation of the gap-state structure of a− S e: Comparison with a− S i: H | |
Kitamura | Effect of Oxygen upon Sintered Cadmium Sulphide Photoconducting Films | |
Myhra et al. | Electron-irradiation induced production and thermal annealing of damage in α-tin | |
Starzhinskiy et al. | New Trends in the Development of A $^{\rm II} $ B $^{\rm VI} $-Based Scintillators | |
Mitrikov et al. | Thermally stimulated exoelectron emission and optically stimulated exoelectron emission of laser evaporated beryllium oxide thin films | |
Piesch et al. | Supralinearity and re-evaluation of different LiF dosimeter types | |
Gilliland Jr et al. | Thermoluminescence studies of the gamma-ray irradiated ferroelectrics Rochelle salt and guanidine aluminum sulfate hexahydrate | |
Cocks et al. | Single‐crystal thermoluminescent lithium fluoride for dosimetry prepared by an edge‐defined film‐fed growth (EFG) technique | |
Hench et al. | Radiation effects in semiconducting glasses |