CA2114539A1 - Improvements in particle detector spatial resolution - Google Patents
Improvements in particle detector spatial resolutionInfo
- Publication number
- CA2114539A1 CA2114539A1 CA002114539A CA2114539A CA2114539A1 CA 2114539 A1 CA2114539 A1 CA 2114539A1 CA 002114539 A CA002114539 A CA 002114539A CA 2114539 A CA2114539 A CA 2114539A CA 2114539 A1 CA2114539 A1 CA 2114539A1
- Authority
- CA
- Canada
- Prior art keywords
- layer
- scintillation
- choosing
- columns
- range
- 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.)
- Abandoned
Links
- 239000002245 particle Substances 0.000 title claims abstract description 41
- 230000006872 improvement Effects 0.000 title description 5
- 239000000463 material Substances 0.000 claims abstract description 169
- 238000000034 method Methods 0.000 claims abstract description 70
- 239000000758 substrate Substances 0.000 claims abstract description 48
- 238000001514 detection method Methods 0.000 claims abstract description 12
- 229920001721 polyimide Polymers 0.000 claims description 17
- 239000004642 Polyimide Substances 0.000 claims description 16
- 229910021417 amorphous silicon Inorganic materials 0.000 claims description 15
- 229910052751 metal Inorganic materials 0.000 claims description 13
- 239000002184 metal Substances 0.000 claims description 13
- 229910052732 germanium Inorganic materials 0.000 claims description 10
- 229910021419 crystalline silicon Inorganic materials 0.000 claims description 9
- 238000007740 vapor deposition Methods 0.000 claims description 9
- GNPVGFCGXDBREM-UHFFFAOYSA-N germanium atom Chemical compound [Ge] GNPVGFCGXDBREM-UHFFFAOYSA-N 0.000 claims description 8
- 150000002739 metals Chemical class 0.000 claims description 8
- 229910052782 aluminium Inorganic materials 0.000 claims description 7
- 238000005530 etching Methods 0.000 claims description 7
- 229910017817 a-Ge Inorganic materials 0.000 claims description 6
- 229910052804 chromium Inorganic materials 0.000 claims description 6
- 229910052737 gold Inorganic materials 0.000 claims description 6
- 229910052753 mercury Inorganic materials 0.000 claims description 6
- 229910052697 platinum Inorganic materials 0.000 claims description 6
- 229910052709 silver Inorganic materials 0.000 claims description 6
- 239000000975 dye Substances 0.000 claims description 5
- 238000011049 filling Methods 0.000 claims description 5
- 239000000976 ink Substances 0.000 claims description 5
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 claims description 5
- 229910052763 palladium Inorganic materials 0.000 claims description 5
- 239000000565 sealant Substances 0.000 claims description 5
- 239000004065 semiconductor Substances 0.000 claims description 5
- 229910045601 alloy Inorganic materials 0.000 claims description 4
- 239000000956 alloy Substances 0.000 claims description 4
- 150000002484 inorganic compounds Chemical class 0.000 claims description 4
- 229910010272 inorganic material Inorganic materials 0.000 claims description 4
- PNDPGZBMCMUPRI-UHFFFAOYSA-N iodine Chemical compound II PNDPGZBMCMUPRI-UHFFFAOYSA-N 0.000 claims description 4
- 150000002894 organic compounds Chemical class 0.000 claims description 4
- 150000003839 salts Chemical class 0.000 claims description 4
- YADSGOSSYOOKMP-UHFFFAOYSA-N lead dioxide Inorganic materials O=[Pb]=O YADSGOSSYOOKMP-UHFFFAOYSA-N 0.000 claims description 2
- 239000012780 transparent material Substances 0.000 claims description 2
- 230000007261 regionalization Effects 0.000 claims 10
- 229910003091 WCl6 Inorganic materials 0.000 claims 3
- 239000012812 sealant material Substances 0.000 claims 3
- KPGXUAIFQMJJFB-UHFFFAOYSA-H tungsten hexachloride Chemical compound Cl[W](Cl)(Cl)(Cl)(Cl)Cl KPGXUAIFQMJJFB-UHFFFAOYSA-H 0.000 claims 3
- 239000004020 conductor Substances 0.000 claims 2
- 239000011358 absorbing material Substances 0.000 abstract description 6
- 239000004952 Polyamide Substances 0.000 abstract 1
- 229920002647 polyamide Polymers 0.000 abstract 1
- XQPRBTXUXXVTKB-UHFFFAOYSA-M caesium iodide Chemical compound [I-].[Cs+] XQPRBTXUXXVTKB-UHFFFAOYSA-M 0.000 description 23
- 238000001704 evaporation Methods 0.000 description 9
- 230000008020 evaporation Effects 0.000 description 9
- NLKNQRATVPKPDG-UHFFFAOYSA-M potassium iodide Chemical compound [K+].[I-] NLKNQRATVPKPDG-UHFFFAOYSA-M 0.000 description 9
- WFUBYPSJBBQSOU-UHFFFAOYSA-M rubidium iodide Chemical compound [Rb+].[I-] WFUBYPSJBBQSOU-UHFFFAOYSA-M 0.000 description 8
- 238000000151 deposition Methods 0.000 description 7
- 230000000694 effects Effects 0.000 description 7
- 229920002120 photoresistant polymer Polymers 0.000 description 7
- 229910052980 cadmium sulfide Inorganic materials 0.000 description 6
- CJOBVZJTOIVNNF-UHFFFAOYSA-N cadmium sulfide Chemical compound [Cd]=S CJOBVZJTOIVNNF-UHFFFAOYSA-N 0.000 description 6
- 230000005855 radiation Effects 0.000 description 6
- 230000008021 deposition Effects 0.000 description 5
- 239000011701 zinc Substances 0.000 description 5
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 4
- 238000013459 approach Methods 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 4
- 239000011521 glass Substances 0.000 description 4
- 230000008569 process Effects 0.000 description 4
- ZCYVEMRRCGMTRW-UHFFFAOYSA-N 7553-56-2 Chemical compound [I] ZCYVEMRRCGMTRW-UHFFFAOYSA-N 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 229910052740 iodine Inorganic materials 0.000 description 3
- 239000011630 iodine Substances 0.000 description 3
- 239000004033 plastic Substances 0.000 description 3
- 239000002904 solvent Substances 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 238000005299 abrasion Methods 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 2
- 150000001298 alcohols Chemical class 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 230000005465 channeling Effects 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 230000005670 electromagnetic radiation Effects 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- FZLIPJUXYLNCLC-UHFFFAOYSA-N lanthanum atom Chemical compound [La] FZLIPJUXYLNCLC-UHFFFAOYSA-N 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 230000003287 optical effect Effects 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 230000035945 sensitivity Effects 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- VZGDMQKNWNREIO-UHFFFAOYSA-N tetrachloromethane Chemical compound ClC(Cl)(Cl)Cl VZGDMQKNWNREIO-UHFFFAOYSA-N 0.000 description 2
- 235000007173 Abies balsamea Nutrition 0.000 description 1
- 239000004857 Balsam Substances 0.000 description 1
- 229910052688 Gadolinium Inorganic materials 0.000 description 1
- 244000018716 Impatiens biflora Species 0.000 description 1
- 229910052779 Neodymium Inorganic materials 0.000 description 1
- 229910052777 Praseodymium Inorganic materials 0.000 description 1
- 229910052581 Si3N4 Inorganic materials 0.000 description 1
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 1
- 239000002250 absorbent Substances 0.000 description 1
- 230000002745 absorbent Effects 0.000 description 1
- 239000006096 absorbing agent Substances 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 239000012190 activator Substances 0.000 description 1
- 230000001668 ameliorated effect Effects 0.000 description 1
- 238000003491 array Methods 0.000 description 1
- 229910052793 cadmium Inorganic materials 0.000 description 1
- BDOSMKKIYDKNTQ-UHFFFAOYSA-N cadmium atom Chemical compound [Cd] BDOSMKKIYDKNTQ-UHFFFAOYSA-N 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000009833 condensation Methods 0.000 description 1
- 230000005494 condensation Effects 0.000 description 1
- 230000008602 contraction Effects 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 239000008367 deionised water Substances 0.000 description 1
- 238000005137 deposition process Methods 0.000 description 1
- ZZEMEJKDTZOXOI-UHFFFAOYSA-N digallium;selenium(2-) Chemical compound [Ga+3].[Ga+3].[Se-2].[Se-2].[Se-2] ZZEMEJKDTZOXOI-UHFFFAOYSA-N 0.000 description 1
- 238000007598 dipping method Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- UIWYJDYFSGRHKR-UHFFFAOYSA-N gadolinium atom Chemical compound [Gd] UIWYJDYFSGRHKR-UHFFFAOYSA-N 0.000 description 1
- 239000003292 glue Substances 0.000 description 1
- 239000004519 grease Substances 0.000 description 1
- AMGQUBHHOARCQH-UHFFFAOYSA-N indium;oxotin Chemical compound [In].[Sn]=O AMGQUBHHOARCQH-UHFFFAOYSA-N 0.000 description 1
- 230000001939 inductive effect Effects 0.000 description 1
- 230000001788 irregular Effects 0.000 description 1
- 229910052746 lanthanum Inorganic materials 0.000 description 1
- 239000011344 liquid material Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 150000002730 mercury Chemical class 0.000 description 1
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 238000000206 photolithography Methods 0.000 description 1
- 239000009719 polyimide resin Substances 0.000 description 1
- 230000001376 precipitating effect Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 229910052761 rare earth metal Inorganic materials 0.000 description 1
- 150000002910 rare earth metals Chemical class 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000007790 scraping Methods 0.000 description 1
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 description 1
- -1 sio2 Substances 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 229910052718 tin Inorganic materials 0.000 description 1
- XOLBLPGZBRYERU-UHFFFAOYSA-N tin dioxide Chemical compound O=[Sn]=O XOLBLPGZBRYERU-UHFFFAOYSA-N 0.000 description 1
- 229910001887 tin oxide Inorganic materials 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- PBYZMCDFOULPGH-UHFFFAOYSA-N tungstate Chemical compound [O-][W]([O-])(=O)=O PBYZMCDFOULPGH-UHFFFAOYSA-N 0.000 description 1
- 238000005019 vapor deposition process Methods 0.000 description 1
- 230000000007 visual effect Effects 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 238000009736 wetting Methods 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
Classifications
-
- 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
- H01L31/02—Details
- H01L31/0232—Optical elements or arrangements associated with the device
- H01L31/02322—Optical elements or arrangements associated with the device comprising luminescent members, e.g. fluorescent sheets upon the device
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
- G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
- G01T1/16—Measuring radiation intensity
- G01T1/20—Measuring radiation intensity with scintillation detectors
- G01T1/2018—Scintillation-photodiode combinations
- G01T1/20183—Arrangements for preventing or correcting crosstalk, e.g. optical or electrical arrangements for correcting crosstalk
Landscapes
- General Physics & Mathematics (AREA)
- Physics & Mathematics (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Life Sciences & Earth Sciences (AREA)
- High Energy & Nuclear Physics (AREA)
- Molecular Biology (AREA)
- Health & Medical Sciences (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- Electromagnetism (AREA)
- Engineering & Computer Science (AREA)
- Computer Hardware Design (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Power Engineering (AREA)
- Measurement Of Radiation (AREA)
Abstract
Method and apparatus (11) for producting separated columns (19) of scintillation layer material (18), for use in detection of X-rays and high energy charged particles (23), with improved spatial resolution. A pattern of ridges or projections (16) is formed on one surface of a substrate layer or in a thin polyamide layer (15), and the scintillation layer (18) is grown at controlled temperature and growth rate on the ridge-containing material (16). The scintillation material (18) preferentially forms cylinders or columns (19), separated by gaps (20) conforming to the pattern of ridges (16), and these columns (19) direct most of the light produced in the scintillation layer (18) along individual columns (19) for subsequent detection in a photodiode layer (13). The gaps (20) may be filled with a light-absorbing material to further enhance the spatial resolution of the particle detector.
Description
W093/03496 ~ s PCr/US92/~ ~8 21i4539 ~
, .. :' .,, : ~ .
IMPR0VEMENTS IN PARTICLE DE~ECTOR~SPA~IAL RESOLUTION ' This application is a continuation-in-part of U.S.
Application No. 07/738,529, filed 07/31/91. ~ This ~;
invention was made with Government support under '' ~ ' Contract No. DE-AC03-76SF00098 between the U.S.
~Department of Energy and the University of California for the operation of Lawrence Berkeley Laboratory. The '~
Government has certain rights in this invention. '':~
Field of the Invention.
This invention relates to improvements in spatial resolution in particle detectors, and more particularly , to a lumine~cent layer in a particle detector.' ,' Backaround-of-the ,Invention -A luminescent,material, such as cesium iodide (CsI), potassium iodide (KI), rubidium iodide (RbI~, gallium selenide (GaySe),, gadolinium~ oxysulphate~ (Gd2OiS),''~ , lanthanum oxysulphate (~a202S), cadmium sulphide (CdS), ,"~zinc~,Scadmiu~,~;sulphide-~(Zn~Cd~.~S)~ cadmium' tungstate ` (C~W03) ,~ or,lead oxide (PbO2), will receivei:'incident 20,~charged particles or photons of high kinetic energy-and convert .part3 or~ :all of this kinetic energy to~ne or a plurality-rof photons~of individual energies lying in the range 1-4,eV. The electromagnetic -radiation emitted by the luminescent material is not'wholly directed in a single forward direction, but is emitted in all directions, although not isotropically. ~ ,,-~ ' - :
wog3~o~96 2~ 2- P~T/US92/06308 Preferably, most or all of this radiation should propagate in approximately the forward direction, toward a photodiode layer that will provide an electrical signal indicating arrival of the incident high energy charged particles or photons. For this reason, many workers have attempted to promote forward direction emission of photons by the light-emitting atoms or molecules contained in the luminescent material.
One early approach to compartmentalization of radiation produced in a luminescent layer is disclosed by MacLeod in U.S.Patent No. 3,041,456, where thin walls, running in two orthogonal directions, of optically transparent material are provided hetween thin adjacent laye'rs or rectangular parallelepipeds of luminescent material.
Another early approach, disclosed by Ligtenberg et al in U.S. Patent No. 3,825,763, provides a substrate of glass or metal (e.g., Al or Ti), on which a thin scintillation layer of CsI or Z~Cdl~S is deposited of unspeciXied thickness. A separation layer of Al203 is deposited on an exposed sur~ace of the scintillation layer, and a photocathode layer of Cs2Sb or similar material is deposited on an exposed surface of the separation layer. The substrate material and the scintillation material have respective thermal ~expansion coefficients of ~2~ 2.5 ~ x 10-5/C, --~respectively, and the substrate-is~maintained at-' an ;~ elevated temperature T; = 150 '- 200C when~ the ~ scintillation material-is -deposited thereon-.~ '`Thé~
substrate-scintillation -:~layer combination is then cooled to room temperature,~and cracks develop in the thin,scintillation layer as cooling;proceeds. These cracks produce columns of scintillation material, separated by small air or vacuum gaps between adjacent columns and extending approximately perpendicularly to ~ `
.,W093/03496 2~ f~ PCT/US92/06308 the substrate-scintillation layer interface. The crack structure thereby produced has a random collection of shapes and associated diameters.
Gudden et al, in U.S.Patent No. 3,829,378, disclose use of a luminescent layer on a screen with an absorbing substance deposited thereon whose absorption decreases as position varies from the center toward the edges o~
the screen. This invention partly compensates for the tendency of screen brightness to decrease as one approaches an edge of the screen.
A process for making columnar structures of a luminescent layer on an X-ray screen is disclosed in U.S.Patent No. 4,069,355 by Lubowski et al.
Depress:ions or valleys are etched at regular intervals in an underlying substrate, and the luminescent materia:L is grown only on the raised portions of the substrate. The gaps between adjacent columns of luminescent material are filled with a highly reflecting material or with another luminescent material. ;
. ., , . , . ,. ,. : , , Sonoda, in U.S.Patent No. 4,239,791, discloses a method for making a screen image intensifier. A heated phosphorescent material layer is treated with a colder liquid material, such as acetone, to cause differential thermal contraction and form a plurality of elongated~
~- cracks -~r~in this~-- layer ~ running approximately perpendicular- to~-the-substrate-phosphorescent layer interface. These cracks-are-~asserted to-form optically independent columns of phosphorescent material.
Riihimaki et al disclose an X-ray intensifying screen with a luminescent layer formed, in an unspecified manner, with a plurality of regularly spaced grooves therein to capture and guide light produced in the ..Wo93/0~96 2 ~ `d ~ 5~' ` ~4~ PCT/USg2/~6308 luminescent layer~ The grooves run in one direction only, and it is unclear how light is channelled within the air or vacuum gaps Swith refractive index = 1) ~ :
between the luminescent material (with refractive index 5 > 1). .
Van Leunen, in U.S. Patent No. 4,712,011, discloses use of the columnar structure produced by the Ligtenberg, et al, invention, and deposits an X-ray-absorbing ~:.
material in the air/vacuum gaps to absorb X-ray light :
10 incident on a gap. Up to five percent of the weight of ~ .
the scintillation layer may be X-ray-absorbing material deposited in the gaps, but no method of depositing the X-ray absorbing material is discussed. :~ ~
,` -':' A method for vapor deposition of a luminescent layer on 15 a screen for image intensification is disclosed by .
Ligtenberg et al in U.S.Patent No. 4,842,894. The vapor deposition crucible is positioned at about 20 relative to the normal to the screen, and gaps formed between columns of the luminescent material appear to 20 be elongated bubbles of unspecified material (possibly air or a vacuum). The luminescent material apparently forms predominantly crystalline columns of this material.
. . . ., -. :
; Bateæ, in.Advances in Electronics and Electron Physics, 25..vol. ~ 28A ~(1969) pp. 451-459,:.~ discloses. use. of ..,~cr~stalline CsI and thermally-induced cracking of a contiguous~substrate, with crack diameter about;0.5 ~m.
`.~It is unclear whether.:the subsequently:grown CsI forms into .spaced apart columns as a result of presence of the substrate cracks.
Stevels and Schrama-dePauw discuss some characteristics of vapor deposited CsI, activated with Na, in Philips Research Reports, vol. 29 (1974) pp. 341-352 and , WOg3/03496 _5_ 211~ ~ 3 ~ PCT/US92/06~g 353-3~2. Cracks are thermally induced in a substrate, held at a temperature of T = 50-300C, and a thick or thin CsI(Na) layer is subsequently grown on a cracked ~' surface of the substrate. Stevels et al discuss the effects of heat treatment, thick versus thin CsI
layers, the substrate material (KI, RbI or other),a,nd average diameter of the cracks on columns of CsI that form on the substrate surface. The possibility of light channeling in such columns is discussed. ' An X-ray image intensifier, using CsI material formed into irregular columns by a cracked mosaic pattern on a substrate, is disclosed by Washida and Sonoda in Advances in Electronics and Electron Physics, vol. 52 '~
(1979) pp. 201-207., The possibility of X-ray channeling is discussed, and two types of column spacings are discussed. Maximum improvement of X-ray intensity, relative to use of a conventional, non-columnar luminescent material, appears to be about 40 percent.
British Patent No. 1,423,935, issued to Philips Electronics and Associated Industries, Ltd., discloses provision of a mosaic crack structure in the form of circles, hexagons and rectangles on a substrate surface. Cesium iodide or a similar luminescent ,, material is subsequently ~vapor deposited on this , surface., It is unclear;whether spaced apart columns of - this vapor depositedv;material form~as a result of-the mosaic crack;structure.-t~
Most or all of the work discussed above relies upon an 30- irregular-,mosaic,crack ,structure, formed by thermal - mismatch or-a similar process, to provide formation of columns, if any, of a deposited luminescent material.
Little or no regularity or control is available for parameters such as column diameters, spacing of W093/0~96i 2 ~ s~ 6- PCT/US92/06308 adjacent columns, or the tendency of such columns to coalesce if the luminescent material is sufficiently thick. What is needed here is a method for column growth of luminescent material that provides control of these parameters and allows flexibility in formation of such struc~ures.
Summary of the Invention These needs are met by the invention, which provides one or more methods for ~abricating a sequence of columns of regular, controllable geometry and diameter perpendicular to the interface o~ the luminescent material with an adjacent material. These columns are separated by gaps that may be evacuate or filled with air, with a light-absorbing material, or with a light-producing or light-reflecting substance. In one smbodiment, a thin layer of polyimide or other suitable etchable material is deposited on a substrate structure and a sequence of ridges or projections is etched in the polyimide material in a predetermined geometrical structure. A luminescent material is slowly grown (rate S 250 ~m/hr) on the ridge-containing surface to produce a plurality of columns separated by gaps in one or two dimensions. The width of a ridge is varied according to the height of the luminescent iayer to be grown so that the columns do not coalesce.
Alternatively, the ridges may be etched directly into ; a substrate ~aterial, such as glass, plastic, metal or - amorphous or crystalline silicon or-igermanium.~ In a third embodiment, the structure ~s put together as a "sandwich" of a first set of layers containing a photodiode-layer and a second set of layers containing ;a luminescent layer.- The columnar structure- thus produced~reduces ~y about 58 percent the optical-spread factor associated with light produced by conversion in the luminescent material, in one embodiment.
~ ~.
~. ~
W093/03496 -7- 211;4;~ Pcr/US92/0~308 Brief Description of the Drawinas Figure 1 is a sectional side view of one embcdiment of apparatus constructed according to the invention.
Figures 2 and 3 are ~ectional side views illustrating the columns formed in the luminescent layer in Figure 1. ...
Figures 4, 5, 6, 7 and 8 are schematic top views of triangular, rectangular, hexagonal, ovular and linear ridge patterns constructed on an underlayer according to the invention.
Figure 9 is a sectional side view of a second embodiment of the apparatus constructed according to the inv'ention.
Figures loA and lOB are sectional views illustrating a third embodiment of the invention.
Figure 11 i8 a graphical view illustrating a measure of the improvement in spatial resolution where the nYention is,.used for~ X-ray and charged particle ,detection. .. . ...
20- Dl~o~G~ehi93L55_~Lhe Invention ,In a first embodiment 11 of the .invention, shown in ,Figure 1,, a , ubstrate, 12 is provided on which a ,photodiode.,.layer,~13 is. depo6ited on one substrate ~-..surface.~-The.substrate~,material may,be glass, plastic, 25,~:a-~,ceramic,.,.,a thin:metal ~layer,..such as.-'Al.or Ti,- or crystalline or amorphous silicon or germanium,:and'the .photodiode material .-i~-~ preferably a hydrogenated ~,amorphous.,;column.-IV., emiconductor material~..such a~
j~,a-Si:H ~or -,a-Ge:H. : A transparent, electrically conductive, thin layer 14 (not drawn to scale) of ,~. material such as indium-tin-oxide ("IT0"), tin-oxide ("T0"), or another suitable thin metal film is then wo 2 1 ~ ~ ~ 9~ PCT/VS92/~308 deposit~d on an exposed surface of the photodiode layer 13 with a thickness of 1-lOo nanometers (nm). The conductive layer 14 is at least partly optically transparent and allows passage of electromagnetic radiation (photons) of appropriate wavelengths between a luminescent layer positioned on one side of the conductive layer and a photodiode layer 13 positioned on the other side of the conductive layer. The photodiode layer 13 and conductive layer 14 are contiguous here. The substrate layer 12 may have any appropriate thickness, and the photodiode layer 13 may have a thickness of 1-10 ~m or 10-100 ~m for amorphous semiconductor material (e.g., a-Si:H or a-Ge:H) or crystalline semiconductor material (e.g., c-Si or c-Ge), respectively. The photodiode layer 13 has a plurali1:y of electrical traces 21 connected at one end to this layer at regular intervals, and these traces are connected at their second ends to readout electronics 22 that receives signals generated within the photodiode layer.
A pattern layer 15 of etchable pattern material 15, such as polyimide resin, sio2, or metals such' as~Al, Cr, Au, Ag, Pd or Pt, of thickness d = 5-20 ~m, is then deposited on an exposed surface of the conductive layer 14 as shown. 'Portions of the pattern Iayer 15 are etched to produce a one-dimensional or two-dimensional sequence~of regularly spaced ridges 16 of the~pattern material that project approximately perpendicularl~ to the interface or~surface 17-between the conductive layer 14' and the pattern layer.-' The ridges''16 have height ~ d~, lateral thickness or width # d2~ ~and are spaced'apart~-from adjacent ridges by ~a distance # d3.
In a-preferred-embodiment, these lengths are dl = 5-20 ~m, d2 = 2-20 ~m, and d3 = 10-100 ~m. The "pitch" of this pattern of ridges, p = d2 + d3, may vary from 15 to 110 ~m. In the etching of the etchable pattern W093/0~96~ 2 1 J 4 ~ ~ 9 - -~ rPCT/US92/~308 material 15, a small portion of this material may be allowed to remain at the interface 17, as shown in Figure 1; or the etchable pattern material 15 may be removed down to the interface 17, except for the ridges 16. In this latter situation, the interface 17 might be covered with a thin layer (not shown in Figure l) of an etch stop material, such as a native oxide or silicon nitride, in a manner well known to workexs in this art.
The structure is then heated to a low temperature T =
- 400C (preferably, T = 100-250C), and a luminescent layer 18 of lumineseent material, such as CsI, KI, RbI, CdS, CdWO3, Zn~Cdl~S, GaySe, Gd202S, La202S, PbOz or other suitable luminescent material, is grown slowly by evaporation at a growth rate < 500 ~m/hr (preferably S 250 ~m/hr) over the interface 17 and ridges 16, to a height d4 #100-1,000 ~m. This evaporation process produces a sequence of cylinders or columns 19 of the luminescent material, separated by air or vacuum gaps 20 of.diameter d~ < d2 because of ,. the presence of the ridges 16 of lateral thickness d2.
Use of a low growth rate improves adhesion and light emission efficiency of the luminescent material.
Certain of the luminescent materials may be activated with Na (CsI), with Tl (CsI), or with a rare earth such as Ce, Pr, Nd or: one of the other 11 rare .earth elements (Gd2O25) :~
.~:.If the thickness ~-of the luminescent layer 18 is ~ade æufficiently .large, it is ~possible.~:that. adjacent 30:..columns 19 will coalesce in an upper part of the layer 18, although the columns 19 will be well separated from one another in the lower part.of this structure...r This is illustrated schematically in Figure 2~ However, if the luminescent layer thickness d4 is kept sufficiently ; ~:~
:.
W093/0~9~ 't _~0_ PCT/US92/06308 small (say, d4 S 1,000 ~m) and the evaporation rate for the luminescent layer 18 is kept small enough, the resulting luminesc~nt layer should consist of columns 19 of luminescent material that are completely separated from one another. For example, a ridge that is d2 = 8 ~m wide will produce a gap between two adjac~nt columns of CsI material that does not close until the heights of the two adjacent columns reaches about 450 ~m. This effect scales approximately linearly with width d2 of the ridge. ~hus, if ridges of lateral width d2 are grown, the thickness d4Of the luminescent layer should preferably be no more than 50 d2 in order to avoid gap closure. However, luminescent layers of thicknesses d~ = 70 d2, or even d4 = 100 d2, prepared according to the invention, will provide improved spatial resolution for particle detection.
Thus, a ridge of width d2 ~ 20 ~m is predicted to produce a gap between two adjacent columns of CsI that does not close for a column height d4 = 1,000 ~m. The other luminescent materials mentioned above are believed to behave qualitatively similarly so that the minimum height requiredi for gap closure scales approximately linearly with ridge width d2. ' `'"' , As illustrated in Figure 3, energetic particles 23 (high energy photons or massive charged particles) that are incident upon the~embodiment ll (Figure 1) first encounter the luminescent layer 18,' and all or a portion of the kinetic energy of these particles is ~ converted~to electromagnetic radiation-or-photons'25, 30: of wavelength AO lying in the range 0.3 ~m-~s ~ S 0.7 ~ m, ,emitted by the~luminescent material. A~photon 25 -~ will; propagate generally toward the int~rface '17 (Figure 1) and~will'encounter and/or be reflected from the wall of the column in which that photon was originally produced. If the incidence angle e of the W093/0~96 ~ 2 1 1 ~ 5 ~`~` J PCT/US92/06~
photon 23 relative to a local tangent to the column wall is sufficiently large (cscqe > cscecr - nL =
refractive index of lumine~cent material at that wavelength~, the photon 25 will undergo total internal reflection and will remain within and propagate within the column in which the photon was originally prod,uced by kinetic energy conversion. If the conversion radiation is assumed to be emitted isotropically by the luminescent material, the trapped fraction ~T Of this emitted radiation that undergoes total internal reflection in the forward direction from a column wall is determined to be ec:r fT = S 2~ sine de /~ 2~ sin e d e = (1 - 1/nL)/2. ( Table I presents the refractive indices and trapped fractions fT for some luminescent materials of interest. Although the fraction fT is less than 0.5, the fact that much of this radiation stays within the 20 column in which it is produced enhances the spatial ~' resolution, of the particle detector constructed according to the embodiment ,11 in Figure 1. This ~
trapped fraction fT is approximately independent of the ~ , height of a column.
25 ,,~able 1. Refractive Index and Trappinq Fraction for ~' Lu~minescent Material CoIumns ``
~-Lu~inescent,~ ~ tive, ;~
, CsI ~ , ~", 1.78 ~, 0.22 KI 1~68 0.20 `
RbI ~ ^ ` 1.65 -~- 0.20 CdS ~ 2.51, , o 30 ' Zn~Cdl,~S 2.36 (est.) 0 29 La2~S ' 1.56 ~ 0.18 ~ ;~
PbOz 2.3 (est.) 0.18 `'' ::
W093/0~96 4~`A~ 5~ PCT/USg2/~308 2 ~ 12~
Figures 4, 5, 6, 7 and 8 are schematic top views of triangular, rectangular, hexagonal, ovular (or circular) and l'linear" arrays that provide suitable one-dimensional and two-dimensional ridge patterns for the etchable material 15 used in the embodiment 11 in Figure 1. The linear array 51 shown in Figure 8 produces a sequence of parallel blocks or columns extending above the regions 55 and separated by gaps defined by the ridges 53. More generally, an array of closed polygonal ridges may be provided to define and promote initial formation of the columns and separating gaps. -Figure 9 illustrates a second embodiment 81 of theinvention, in which the order of some of the layers is reversed. A substrate layer 83 is patterned and etched to provide a sequence of ridges 85 of the substrate material extending approximately perpendicularly to the adjacent surface of the substrate. As before, the substrate layer material may be glass, plastic, thin metal, or crystalline or amorphous silicon or germanium. Alternatively, a thin polyimide layer 84 may be deposited on the exposed surface of the substrate 83 and used for ridge formation by etching. A
luminescent layer 87, containing luminescent material such as CsI, KI, RbI, CdS, ZnxCdl~S, CdW03, G~Se, Gd202S, La202S or PbOz, with or without any of the ~activators~méntio`ned above,;is then slowly evaporated over~ the substrate 83 patterned with the ridges 85, with the substrate temperature T being held rêlatively low at T = 100-250C. The luminescent material forms into a plurality of columns 89 that are separated by a sequence of air or vacuum gaps 91 defined by the ridges -85 as in Figure 1. A sealant layer 93 of polyimide or similar materials is deposited over the luminescent layer 87, and an optically transparent conductive layer 95 of IT0 or T0 is then deposited over the sealant W093/0~96 t 06308 -13- 2 1 1i4 ~3;9~
layer 93. Finally, a photodiode layer 97 of a;-Si:H, a-~e:H or mixture thereof is deposited over the conductive layer. The dimensions dl~ d2, d3 and d4 of the ridges 85 and lumine~cent layer 87 are as in Figure 1. The sealant layer 93, the conductive layer 95 and the photodiode layer 97 have preferred thicknesses-in the respective ranges 5-10 ~m, 1-100 nm, and 1-10 ~m (or 10-100 ~m), respectively. Energetic particles 99 are incident upon the structure 81 and will pass through the luminescent layer 87 before passing through the photodiode layer 97.
Figure lOA illustrates a third embodiment of the invention, which is initially constructed as two separate sets of layers. The first set of layers includes a substrate 101, of arbitrary thickness, with a photodiode layer 103 of a-Si:H, a-Ge:H (or a co~bination thereof), c-Si or c-Ge deposited on the first substrate 101. As in the other two embodiments, the thickness of the photodiode layer may be 1-10 ~m for amorphous Si or Ge and 10-100 ~m for crystalline Si or Ge. The second set of layers includes a'second substrate 105,' on which is deposited a luminescent layer including a plurality of cylinders or columns 107 of luminescent material, such as CsI, KI, RbI, CdS, Zn~Cdl.~S, CdW03, GaySe, Gd2~2S, La202S or PbOz, . The - columns 107 are separated by' a plurality of ~ 'one-dimensional:'or two-dimensional gaps 109 that are : t~i-nitially`'formed using ridges 111. The ridgès'lli are 'in' t~rn formed:as in the'lfirst^-or''sécond:embodiments, . 30 : by -etching polyimide or another suitable' etchable ';~ material'or by etching the underlying''substrate'105.
~ In-'Figure lOB',:the first'and sécond set of-layers^are brought together as a "sandwich" and are, optionally, held together using''a suitable "glue", such as optical grease, Canadian balsam or other suitable material that produces no effluents when this material cures and W~93/o~g6 21~i4 ~3 9 ~ -14- PCT/US92/06308 , , . :
hardens. The assembled apparatus, as shown in Figure lOB with the associated electronics 113, then functions as a particle detector with improved spati~l resolution. One advantage of this third embodiment is that the first and second sets of layers may be fabricated independently. If a high temperature is needed to fabricate the columnar luminescent layar 107, the photodiodP layer 103 is fabricated separately and is not subjected to this high temperature. Readout electronics is also present, but not shown, in Figures 2, 3, 9 and 10B.
Example~ The following procedure is preferred for producing a ridge pattern in a polyimide layer. The substrat:e used should be rinsed in de-ionized water at a temperature of T = 80C for a time interval ~t = 3 -10 minutes. Polyimide material, such as DuPont PI
2555, is spun on an exposed surface of the substrate at a rotation rate of about 3500 rpm for a time interval ~t = 30 sec, or for a time sufficient to produce a polyimide layer of an approximate thickness of 3.5 ~m.
Alternatively, DuPont PI 2722 material, which contains both the polyimide and a photoresist material, may be used in place of the PI 2555 material. The substrate-polyimide layer combination is then softbaked for about 3 min at a temperature T = 90C.
Photoresist, such as KTI 820, is then spun on top of the polyimide layer at a rotation speed of about 3500 rp~ for a time interval.~t = 30 secj or for a time ; ~ufficient-to produce aiphotoresist thickness of 2.5 -3.4 ~m. The ~ubstrate-polyimide layer-photoresist layer is~then softbaked for 2 min. at-a temperature T
= 120C.!- - The- photoresist is then exposed to ultraviolet radiation in the desired pattern for about 15 sec, using photolithography equipment and procedures known in the art. The irradiated photoresist is then baked for about 60 sec. and is devaloped. The ~W093/0~96. -15- 2f ~?~ ~ PcT~us92/o63o8 photoresist is immersed in a suitable developer, such as Kodak 934, for about 120 sec., then rinsed and dried. The polyimide is etched simultaneously when the photoresist is developed. The resulting ridge structure is then hardbaked or cured for at least one hour at a temperature of T = 280C, or for one half hour at T = 350C. The scintillation layer material is then coated on the ridge structure to the desired thickness d4 = 100 - 1,000 ~m, using a low evaporation rate to allow columns of scintillation material to ~orm in conformity to the ridge pattern provided.
Figure 11 is a graphical view illustrating the improvement in spatial resolution, using the invention in one embodiment. The solid circles represent 15 intensity of light received through a conventional, unstructured layer of CsI of thickness 450 ~m with an a-Si:H photodiode layer and have an associated FWHM of 540 ~m about a selected central position at x = 1,500 ~m.. The triangles represent intensity of light received through a columnar structure of 450 ~m thick CsI, fa~ricated according to the invention, with an a-Si:H~photodiode layer in tbe same configuration.
Here, the FWHM is 230 ~m, a reduction of about 58 percent in the point spread width in one dimension; in two dimensions, the point spread width reduction is estimated to be about 72 percent. A particle detector constructed-using-the invention disclosed`here may i:~resolve:.lateral spa~ial eeparations-às smal~l-as lo - 50 30 ..~he gaps 20~or 91 or-109 in Figures 1, 2,~9 or lOA/lOB
may be filled, by~capillary action or otherwise, with a light-absorbing material, -such` as Te, Sb or Sn (useful for CsI), to reduce the point spread factor associated with light produced in a luminescent layer column fabricated according to the invention. Using ,. w093/0~96 2;1 1 4 ~ 3 9 -16- PCT/US92/~30g ~, this embodiment, most of the light that is not internally reflected within a given column is absorbed by the material in an adjacent gap and does not appear in another such column. This will reduce the total amount of light produced and transmitted by the luminescent layer but will improve the spat,,ial resolution by ensuring that substantially all light produced in a given column of luminescent material will either be absorbed or will propagate within that column to the photodiode layer, where associated rea~out electronics 22 (Figure 1) detects which column of luminescent material produced the material. ~ The absorbing material used here should have an optical absorpt:ion edge that reaches its maximum near, but below, the range of wavelengths produced by the luminescent material.
It is advantageous in the inventive method to provide interstitial material in the gaps between the cylinders or column ætructures which comprise the scintillation layer of,the inventive detector. Spatial resolution can be improved by from 10% to 30% using this approach.
The iinter~titial material~,serves a variety of functions, including increasing structural integrity of the scintillation layer and improving the sensitivity of the detection capability.
,.-Interstitial, material increases~the sensitivity of ~, detection .by limiting,the intercolumnar. transfer.i of light, particles, heat, and other factors. .:!.For instance, low energy X-rays are typically generated in the columns. These;. will o~ten be emitted from the ... column wall,,-,gener.,a,lly at an.incident angle., When,this .- occurs, the low energy X-rays commonly impact adjacent . columns, inducing cross talk in the detector of the -. adjacent column. This background signal lessens the acuity of the resulting detector, and compromises its ~W093/03496 17- ? `
acuity of the resulting detector, and compromises its spatial resolution.
Scintillation layer light generation which occurs at the periphery of the columnar surface or communicates to the interstitial areas also is a source of background noise. For instance, light which escapes internal reflection may enter an adjacent column, or even scatter farther afield of the actual point of production. As such, it will give a false reading as to the spatial position of the particle impact.
The ill effects of random light scatter and detection of errant low energy X-rays can be limited or fully ameliorated by the use of interstitial materials. The choice of the material depends on a compromise between the desired results and ease of application. For instance, a multipurpose material would absorb both light and X-rays. Even if such a material did not have optimum qualities in both these functions, if it can perform both to a reasonable level it may be the material of choice. Examples of such multipurpose materials are Tl2O and WC16~
,; - , :
For light attenuation, it is useful to provide an interstitial material that absorbs light in the range of 300-700 nm in wave length. Alternatively,- the intersti*ial material may-be reflective ~-in nature.
~e This has the advantage of returning the~light signal to :the-appropriatel!column.-~ The use of- such- materials ~allows the possibility of the light being correctly redirected through the column thus preventing a reading error.~
Appropriate candidates for light absorbing interstitial materials are various dyes and inks, Dykem Blue, Sr. W~ 93/0~96 2 ~ PCT/US92/06308 ~ -18-mercury and its salts, metals and their alloys, iodine and the like.
Interstitial material should have the capacity to absorb low energy X-rays produced within columns and capa~le of reaching adjacent columns. This quality is exemplified by a hi~h density and a high Z value, preferably above 50. Mercury has high Z value and high density, and so is an excellent absorber of errant low energy X-rays. Mercury salts would have similar capacities. At a Z value of 50, iodine is in an acceptable range of X-ray absorption capability;
:, Various methods for depositing the desired material in the interstitial areas of the scintillation layer are availab.le. Two useful methods are vapor deposition and application through a solute carrier. Common objectives of these two methods are to achieve uniformity of layer deposition, fuIl penetration of the interstitial area, and excellent adhesion of the layer to the substrate.
.: .; ., , Vapor deposition must occur at a temperature which will not damage various components of the detector. In one example of the present invention, the cesium iodide . layer is the limiting material in this regard.
Therefore, :~ materials ~ selected for evaporation 25.:deposition in this case.:must have. an.~evaporation temperature of- less than.650~degrees Celsius.~. Good ..candidates.-for.this process are..thus.mercury~,.with.an .evaporation. temperature of 365.degrees Celsius, and . iodine, with an:evaporation.temperature of less than 200 degrees Celsius. Various organic and inorganic compounds will also be usefuI in the vapor deposition process.
.
.`` wo g3/0~96 ` 2 1 11'~ 5~ i PCr/US92/06308 ~ ~ --19--Vapor deposition is accomplished by confining the scintillator and the interstitial material within an enclosed vessel. The interstitial material is then evaporated, and recondensed on the substrate sur~ace and interstitial area. In most cases, the material is heated to provide the necessary evaporation. The su~strate is preferably heated to increase wetting and creep effects, and to improve adherence. A higher quality deposition in a shorter period of time is achieved compared to a system where the substrate is not heated. Typically, the entire treatment chamber is warmed to avoid preferential deposition on the c~amber wall.
As a rule, the more gradual the heating and subsequent coolingl, the finer the quality of the resultant deposited layer. Placing the substrate towards the top of the chamber avoids droplets of precipitating interstitial material should the chamber become supersal:urated. One wishes to avoid the ~ormation of liquid on the surface of the substrate prior to the filling of the interstitial areas. ~ Processing parameters~ can be modified to assure that the condensation occurs uniformly within the columnar intersticial regions.
The- interstitial area can also be filled using !~materials dissolved or suspended in a liquid carrier.
---In the-case:of the presently described materials, water~
''!~',' asra olvent is;counter-indicated because of its ill effect on the inventive materials. Useful solvents in this regard are non-aqueous materials such as acetone, carbon tetrachloride, anhydrous alcohols and the like.
While a solution close to saturation with the material to be deposited is generally preferred, this consideration must be balanced by the ill effects of a - . .:
1 W093/0~96 21~..5~ PCT/U~92/~ ~8 ' -20~
viscous solution. Some amount of heating is possible to alleviate this problem.
Appropriate solutions for treatment of the inventive scintillation layers are iodine dissolved in anhydrous methyl or higher alcohols, or commercial dye mater,ials such as organic inks. Sequential dipping and five minute drying produces an excellent result with these materials.
A required finishing step is common to both the vapor deposition and the solution deposition processes. If filling of the interstices to the surface level is to be assured, deposition must also be allowed on the surface. However, in the functioning detector, this layer must be removed. There are many methods available for removing this surface coating, including chemical dissolution and mechanical abrasion.
Solvent removal of the surface film must be approached with care to avoid damage of the interstitial deposits.
Typically, the solvent is provided in an absorbent material, such as a blotter, and wiped across the surface. This is done only until visual observation indicates removal of the undesired film.
Mechanical abrasion can also be used to remove the ~excess film layer. Simple sanding,or scraping will 25",--of~ten,surface for-the-needs~of the-present invention.
This may have-an advantageous effect of preparing the surface~for application of additional components.
, .. :' .,, : ~ .
IMPR0VEMENTS IN PARTICLE DE~ECTOR~SPA~IAL RESOLUTION ' This application is a continuation-in-part of U.S.
Application No. 07/738,529, filed 07/31/91. ~ This ~;
invention was made with Government support under '' ~ ' Contract No. DE-AC03-76SF00098 between the U.S.
~Department of Energy and the University of California for the operation of Lawrence Berkeley Laboratory. The '~
Government has certain rights in this invention. '':~
Field of the Invention.
This invention relates to improvements in spatial resolution in particle detectors, and more particularly , to a lumine~cent layer in a particle detector.' ,' Backaround-of-the ,Invention -A luminescent,material, such as cesium iodide (CsI), potassium iodide (KI), rubidium iodide (RbI~, gallium selenide (GaySe),, gadolinium~ oxysulphate~ (Gd2OiS),''~ , lanthanum oxysulphate (~a202S), cadmium sulphide (CdS), ,"~zinc~,Scadmiu~,~;sulphide-~(Zn~Cd~.~S)~ cadmium' tungstate ` (C~W03) ,~ or,lead oxide (PbO2), will receivei:'incident 20,~charged particles or photons of high kinetic energy-and convert .part3 or~ :all of this kinetic energy to~ne or a plurality-rof photons~of individual energies lying in the range 1-4,eV. The electromagnetic -radiation emitted by the luminescent material is not'wholly directed in a single forward direction, but is emitted in all directions, although not isotropically. ~ ,,-~ ' - :
wog3~o~96 2~ 2- P~T/US92/06308 Preferably, most or all of this radiation should propagate in approximately the forward direction, toward a photodiode layer that will provide an electrical signal indicating arrival of the incident high energy charged particles or photons. For this reason, many workers have attempted to promote forward direction emission of photons by the light-emitting atoms or molecules contained in the luminescent material.
One early approach to compartmentalization of radiation produced in a luminescent layer is disclosed by MacLeod in U.S.Patent No. 3,041,456, where thin walls, running in two orthogonal directions, of optically transparent material are provided hetween thin adjacent laye'rs or rectangular parallelepipeds of luminescent material.
Another early approach, disclosed by Ligtenberg et al in U.S. Patent No. 3,825,763, provides a substrate of glass or metal (e.g., Al or Ti), on which a thin scintillation layer of CsI or Z~Cdl~S is deposited of unspeciXied thickness. A separation layer of Al203 is deposited on an exposed sur~ace of the scintillation layer, and a photocathode layer of Cs2Sb or similar material is deposited on an exposed surface of the separation layer. The substrate material and the scintillation material have respective thermal ~expansion coefficients of ~2~ 2.5 ~ x 10-5/C, --~respectively, and the substrate-is~maintained at-' an ;~ elevated temperature T; = 150 '- 200C when~ the ~ scintillation material-is -deposited thereon-.~ '`Thé~
substrate-scintillation -:~layer combination is then cooled to room temperature,~and cracks develop in the thin,scintillation layer as cooling;proceeds. These cracks produce columns of scintillation material, separated by small air or vacuum gaps between adjacent columns and extending approximately perpendicularly to ~ `
.,W093/03496 2~ f~ PCT/US92/06308 the substrate-scintillation layer interface. The crack structure thereby produced has a random collection of shapes and associated diameters.
Gudden et al, in U.S.Patent No. 3,829,378, disclose use of a luminescent layer on a screen with an absorbing substance deposited thereon whose absorption decreases as position varies from the center toward the edges o~
the screen. This invention partly compensates for the tendency of screen brightness to decrease as one approaches an edge of the screen.
A process for making columnar structures of a luminescent layer on an X-ray screen is disclosed in U.S.Patent No. 4,069,355 by Lubowski et al.
Depress:ions or valleys are etched at regular intervals in an underlying substrate, and the luminescent materia:L is grown only on the raised portions of the substrate. The gaps between adjacent columns of luminescent material are filled with a highly reflecting material or with another luminescent material. ;
. ., , . , . ,. ,. : , , Sonoda, in U.S.Patent No. 4,239,791, discloses a method for making a screen image intensifier. A heated phosphorescent material layer is treated with a colder liquid material, such as acetone, to cause differential thermal contraction and form a plurality of elongated~
~- cracks -~r~in this~-- layer ~ running approximately perpendicular- to~-the-substrate-phosphorescent layer interface. These cracks-are-~asserted to-form optically independent columns of phosphorescent material.
Riihimaki et al disclose an X-ray intensifying screen with a luminescent layer formed, in an unspecified manner, with a plurality of regularly spaced grooves therein to capture and guide light produced in the ..Wo93/0~96 2 ~ `d ~ 5~' ` ~4~ PCT/USg2/~6308 luminescent layer~ The grooves run in one direction only, and it is unclear how light is channelled within the air or vacuum gaps Swith refractive index = 1) ~ :
between the luminescent material (with refractive index 5 > 1). .
Van Leunen, in U.S. Patent No. 4,712,011, discloses use of the columnar structure produced by the Ligtenberg, et al, invention, and deposits an X-ray-absorbing ~:.
material in the air/vacuum gaps to absorb X-ray light :
10 incident on a gap. Up to five percent of the weight of ~ .
the scintillation layer may be X-ray-absorbing material deposited in the gaps, but no method of depositing the X-ray absorbing material is discussed. :~ ~
,` -':' A method for vapor deposition of a luminescent layer on 15 a screen for image intensification is disclosed by .
Ligtenberg et al in U.S.Patent No. 4,842,894. The vapor deposition crucible is positioned at about 20 relative to the normal to the screen, and gaps formed between columns of the luminescent material appear to 20 be elongated bubbles of unspecified material (possibly air or a vacuum). The luminescent material apparently forms predominantly crystalline columns of this material.
. . . ., -. :
; Bateæ, in.Advances in Electronics and Electron Physics, 25..vol. ~ 28A ~(1969) pp. 451-459,:.~ discloses. use. of ..,~cr~stalline CsI and thermally-induced cracking of a contiguous~substrate, with crack diameter about;0.5 ~m.
`.~It is unclear whether.:the subsequently:grown CsI forms into .spaced apart columns as a result of presence of the substrate cracks.
Stevels and Schrama-dePauw discuss some characteristics of vapor deposited CsI, activated with Na, in Philips Research Reports, vol. 29 (1974) pp. 341-352 and , WOg3/03496 _5_ 211~ ~ 3 ~ PCT/US92/06~g 353-3~2. Cracks are thermally induced in a substrate, held at a temperature of T = 50-300C, and a thick or thin CsI(Na) layer is subsequently grown on a cracked ~' surface of the substrate. Stevels et al discuss the effects of heat treatment, thick versus thin CsI
layers, the substrate material (KI, RbI or other),a,nd average diameter of the cracks on columns of CsI that form on the substrate surface. The possibility of light channeling in such columns is discussed. ' An X-ray image intensifier, using CsI material formed into irregular columns by a cracked mosaic pattern on a substrate, is disclosed by Washida and Sonoda in Advances in Electronics and Electron Physics, vol. 52 '~
(1979) pp. 201-207., The possibility of X-ray channeling is discussed, and two types of column spacings are discussed. Maximum improvement of X-ray intensity, relative to use of a conventional, non-columnar luminescent material, appears to be about 40 percent.
British Patent No. 1,423,935, issued to Philips Electronics and Associated Industries, Ltd., discloses provision of a mosaic crack structure in the form of circles, hexagons and rectangles on a substrate surface. Cesium iodide or a similar luminescent ,, material is subsequently ~vapor deposited on this , surface., It is unclear;whether spaced apart columns of - this vapor depositedv;material form~as a result of-the mosaic crack;structure.-t~
Most or all of the work discussed above relies upon an 30- irregular-,mosaic,crack ,structure, formed by thermal - mismatch or-a similar process, to provide formation of columns, if any, of a deposited luminescent material.
Little or no regularity or control is available for parameters such as column diameters, spacing of W093/0~96i 2 ~ s~ 6- PCT/US92/06308 adjacent columns, or the tendency of such columns to coalesce if the luminescent material is sufficiently thick. What is needed here is a method for column growth of luminescent material that provides control of these parameters and allows flexibility in formation of such struc~ures.
Summary of the Invention These needs are met by the invention, which provides one or more methods for ~abricating a sequence of columns of regular, controllable geometry and diameter perpendicular to the interface o~ the luminescent material with an adjacent material. These columns are separated by gaps that may be evacuate or filled with air, with a light-absorbing material, or with a light-producing or light-reflecting substance. In one smbodiment, a thin layer of polyimide or other suitable etchable material is deposited on a substrate structure and a sequence of ridges or projections is etched in the polyimide material in a predetermined geometrical structure. A luminescent material is slowly grown (rate S 250 ~m/hr) on the ridge-containing surface to produce a plurality of columns separated by gaps in one or two dimensions. The width of a ridge is varied according to the height of the luminescent iayer to be grown so that the columns do not coalesce.
Alternatively, the ridges may be etched directly into ; a substrate ~aterial, such as glass, plastic, metal or - amorphous or crystalline silicon or-igermanium.~ In a third embodiment, the structure ~s put together as a "sandwich" of a first set of layers containing a photodiode-layer and a second set of layers containing ;a luminescent layer.- The columnar structure- thus produced~reduces ~y about 58 percent the optical-spread factor associated with light produced by conversion in the luminescent material, in one embodiment.
~ ~.
~. ~
W093/03496 -7- 211;4;~ Pcr/US92/0~308 Brief Description of the Drawinas Figure 1 is a sectional side view of one embcdiment of apparatus constructed according to the invention.
Figures 2 and 3 are ~ectional side views illustrating the columns formed in the luminescent layer in Figure 1. ...
Figures 4, 5, 6, 7 and 8 are schematic top views of triangular, rectangular, hexagonal, ovular and linear ridge patterns constructed on an underlayer according to the invention.
Figure 9 is a sectional side view of a second embodiment of the apparatus constructed according to the inv'ention.
Figures loA and lOB are sectional views illustrating a third embodiment of the invention.
Figure 11 i8 a graphical view illustrating a measure of the improvement in spatial resolution where the nYention is,.used for~ X-ray and charged particle ,detection. .. . ...
20- Dl~o~G~ehi93L55_~Lhe Invention ,In a first embodiment 11 of the .invention, shown in ,Figure 1,, a , ubstrate, 12 is provided on which a ,photodiode.,.layer,~13 is. depo6ited on one substrate ~-..surface.~-The.substrate~,material may,be glass, plastic, 25,~:a-~,ceramic,.,.,a thin:metal ~layer,..such as.-'Al.or Ti,- or crystalline or amorphous silicon or germanium,:and'the .photodiode material .-i~-~ preferably a hydrogenated ~,amorphous.,;column.-IV., emiconductor material~..such a~
j~,a-Si:H ~or -,a-Ge:H. : A transparent, electrically conductive, thin layer 14 (not drawn to scale) of ,~. material such as indium-tin-oxide ("IT0"), tin-oxide ("T0"), or another suitable thin metal film is then wo 2 1 ~ ~ ~ 9~ PCT/VS92/~308 deposit~d on an exposed surface of the photodiode layer 13 with a thickness of 1-lOo nanometers (nm). The conductive layer 14 is at least partly optically transparent and allows passage of electromagnetic radiation (photons) of appropriate wavelengths between a luminescent layer positioned on one side of the conductive layer and a photodiode layer 13 positioned on the other side of the conductive layer. The photodiode layer 13 and conductive layer 14 are contiguous here. The substrate layer 12 may have any appropriate thickness, and the photodiode layer 13 may have a thickness of 1-10 ~m or 10-100 ~m for amorphous semiconductor material (e.g., a-Si:H or a-Ge:H) or crystalline semiconductor material (e.g., c-Si or c-Ge), respectively. The photodiode layer 13 has a plurali1:y of electrical traces 21 connected at one end to this layer at regular intervals, and these traces are connected at their second ends to readout electronics 22 that receives signals generated within the photodiode layer.
A pattern layer 15 of etchable pattern material 15, such as polyimide resin, sio2, or metals such' as~Al, Cr, Au, Ag, Pd or Pt, of thickness d = 5-20 ~m, is then deposited on an exposed surface of the conductive layer 14 as shown. 'Portions of the pattern Iayer 15 are etched to produce a one-dimensional or two-dimensional sequence~of regularly spaced ridges 16 of the~pattern material that project approximately perpendicularl~ to the interface or~surface 17-between the conductive layer 14' and the pattern layer.-' The ridges''16 have height ~ d~, lateral thickness or width # d2~ ~and are spaced'apart~-from adjacent ridges by ~a distance # d3.
In a-preferred-embodiment, these lengths are dl = 5-20 ~m, d2 = 2-20 ~m, and d3 = 10-100 ~m. The "pitch" of this pattern of ridges, p = d2 + d3, may vary from 15 to 110 ~m. In the etching of the etchable pattern W093/0~96~ 2 1 J 4 ~ ~ 9 - -~ rPCT/US92/~308 material 15, a small portion of this material may be allowed to remain at the interface 17, as shown in Figure 1; or the etchable pattern material 15 may be removed down to the interface 17, except for the ridges 16. In this latter situation, the interface 17 might be covered with a thin layer (not shown in Figure l) of an etch stop material, such as a native oxide or silicon nitride, in a manner well known to workexs in this art.
The structure is then heated to a low temperature T =
- 400C (preferably, T = 100-250C), and a luminescent layer 18 of lumineseent material, such as CsI, KI, RbI, CdS, CdWO3, Zn~Cdl~S, GaySe, Gd202S, La202S, PbOz or other suitable luminescent material, is grown slowly by evaporation at a growth rate < 500 ~m/hr (preferably S 250 ~m/hr) over the interface 17 and ridges 16, to a height d4 #100-1,000 ~m. This evaporation process produces a sequence of cylinders or columns 19 of the luminescent material, separated by air or vacuum gaps 20 of.diameter d~ < d2 because of ,. the presence of the ridges 16 of lateral thickness d2.
Use of a low growth rate improves adhesion and light emission efficiency of the luminescent material.
Certain of the luminescent materials may be activated with Na (CsI), with Tl (CsI), or with a rare earth such as Ce, Pr, Nd or: one of the other 11 rare .earth elements (Gd2O25) :~
.~:.If the thickness ~-of the luminescent layer 18 is ~ade æufficiently .large, it is ~possible.~:that. adjacent 30:..columns 19 will coalesce in an upper part of the layer 18, although the columns 19 will be well separated from one another in the lower part.of this structure...r This is illustrated schematically in Figure 2~ However, if the luminescent layer thickness d4 is kept sufficiently ; ~:~
:.
W093/0~9~ 't _~0_ PCT/US92/06308 small (say, d4 S 1,000 ~m) and the evaporation rate for the luminescent layer 18 is kept small enough, the resulting luminesc~nt layer should consist of columns 19 of luminescent material that are completely separated from one another. For example, a ridge that is d2 = 8 ~m wide will produce a gap between two adjac~nt columns of CsI material that does not close until the heights of the two adjacent columns reaches about 450 ~m. This effect scales approximately linearly with width d2 of the ridge. ~hus, if ridges of lateral width d2 are grown, the thickness d4Of the luminescent layer should preferably be no more than 50 d2 in order to avoid gap closure. However, luminescent layers of thicknesses d~ = 70 d2, or even d4 = 100 d2, prepared according to the invention, will provide improved spatial resolution for particle detection.
Thus, a ridge of width d2 ~ 20 ~m is predicted to produce a gap between two adjacent columns of CsI that does not close for a column height d4 = 1,000 ~m. The other luminescent materials mentioned above are believed to behave qualitatively similarly so that the minimum height requiredi for gap closure scales approximately linearly with ridge width d2. ' `'"' , As illustrated in Figure 3, energetic particles 23 (high energy photons or massive charged particles) that are incident upon the~embodiment ll (Figure 1) first encounter the luminescent layer 18,' and all or a portion of the kinetic energy of these particles is ~ converted~to electromagnetic radiation-or-photons'25, 30: of wavelength AO lying in the range 0.3 ~m-~s ~ S 0.7 ~ m, ,emitted by the~luminescent material. A~photon 25 -~ will; propagate generally toward the int~rface '17 (Figure 1) and~will'encounter and/or be reflected from the wall of the column in which that photon was originally produced. If the incidence angle e of the W093/0~96 ~ 2 1 1 ~ 5 ~`~` J PCT/US92/06~
photon 23 relative to a local tangent to the column wall is sufficiently large (cscqe > cscecr - nL =
refractive index of lumine~cent material at that wavelength~, the photon 25 will undergo total internal reflection and will remain within and propagate within the column in which the photon was originally prod,uced by kinetic energy conversion. If the conversion radiation is assumed to be emitted isotropically by the luminescent material, the trapped fraction ~T Of this emitted radiation that undergoes total internal reflection in the forward direction from a column wall is determined to be ec:r fT = S 2~ sine de /~ 2~ sin e d e = (1 - 1/nL)/2. ( Table I presents the refractive indices and trapped fractions fT for some luminescent materials of interest. Although the fraction fT is less than 0.5, the fact that much of this radiation stays within the 20 column in which it is produced enhances the spatial ~' resolution, of the particle detector constructed according to the embodiment ,11 in Figure 1. This ~
trapped fraction fT is approximately independent of the ~ , height of a column.
25 ,,~able 1. Refractive Index and Trappinq Fraction for ~' Lu~minescent Material CoIumns ``
~-Lu~inescent,~ ~ tive, ;~
, CsI ~ , ~", 1.78 ~, 0.22 KI 1~68 0.20 `
RbI ~ ^ ` 1.65 -~- 0.20 CdS ~ 2.51, , o 30 ' Zn~Cdl,~S 2.36 (est.) 0 29 La2~S ' 1.56 ~ 0.18 ~ ;~
PbOz 2.3 (est.) 0.18 `'' ::
W093/0~96 4~`A~ 5~ PCT/USg2/~308 2 ~ 12~
Figures 4, 5, 6, 7 and 8 are schematic top views of triangular, rectangular, hexagonal, ovular (or circular) and l'linear" arrays that provide suitable one-dimensional and two-dimensional ridge patterns for the etchable material 15 used in the embodiment 11 in Figure 1. The linear array 51 shown in Figure 8 produces a sequence of parallel blocks or columns extending above the regions 55 and separated by gaps defined by the ridges 53. More generally, an array of closed polygonal ridges may be provided to define and promote initial formation of the columns and separating gaps. -Figure 9 illustrates a second embodiment 81 of theinvention, in which the order of some of the layers is reversed. A substrate layer 83 is patterned and etched to provide a sequence of ridges 85 of the substrate material extending approximately perpendicularly to the adjacent surface of the substrate. As before, the substrate layer material may be glass, plastic, thin metal, or crystalline or amorphous silicon or germanium. Alternatively, a thin polyimide layer 84 may be deposited on the exposed surface of the substrate 83 and used for ridge formation by etching. A
luminescent layer 87, containing luminescent material such as CsI, KI, RbI, CdS, ZnxCdl~S, CdW03, G~Se, Gd202S, La202S or PbOz, with or without any of the ~activators~méntio`ned above,;is then slowly evaporated over~ the substrate 83 patterned with the ridges 85, with the substrate temperature T being held rêlatively low at T = 100-250C. The luminescent material forms into a plurality of columns 89 that are separated by a sequence of air or vacuum gaps 91 defined by the ridges -85 as in Figure 1. A sealant layer 93 of polyimide or similar materials is deposited over the luminescent layer 87, and an optically transparent conductive layer 95 of IT0 or T0 is then deposited over the sealant W093/0~96 t 06308 -13- 2 1 1i4 ~3;9~
layer 93. Finally, a photodiode layer 97 of a;-Si:H, a-~e:H or mixture thereof is deposited over the conductive layer. The dimensions dl~ d2, d3 and d4 of the ridges 85 and lumine~cent layer 87 are as in Figure 1. The sealant layer 93, the conductive layer 95 and the photodiode layer 97 have preferred thicknesses-in the respective ranges 5-10 ~m, 1-100 nm, and 1-10 ~m (or 10-100 ~m), respectively. Energetic particles 99 are incident upon the structure 81 and will pass through the luminescent layer 87 before passing through the photodiode layer 97.
Figure lOA illustrates a third embodiment of the invention, which is initially constructed as two separate sets of layers. The first set of layers includes a substrate 101, of arbitrary thickness, with a photodiode layer 103 of a-Si:H, a-Ge:H (or a co~bination thereof), c-Si or c-Ge deposited on the first substrate 101. As in the other two embodiments, the thickness of the photodiode layer may be 1-10 ~m for amorphous Si or Ge and 10-100 ~m for crystalline Si or Ge. The second set of layers includes a'second substrate 105,' on which is deposited a luminescent layer including a plurality of cylinders or columns 107 of luminescent material, such as CsI, KI, RbI, CdS, Zn~Cdl.~S, CdW03, GaySe, Gd2~2S, La202S or PbOz, . The - columns 107 are separated by' a plurality of ~ 'one-dimensional:'or two-dimensional gaps 109 that are : t~i-nitially`'formed using ridges 111. The ridgès'lli are 'in' t~rn formed:as in the'lfirst^-or''sécond:embodiments, . 30 : by -etching polyimide or another suitable' etchable ';~ material'or by etching the underlying''substrate'105.
~ In-'Figure lOB',:the first'and sécond set of-layers^are brought together as a "sandwich" and are, optionally, held together using''a suitable "glue", such as optical grease, Canadian balsam or other suitable material that produces no effluents when this material cures and W~93/o~g6 21~i4 ~3 9 ~ -14- PCT/US92/06308 , , . :
hardens. The assembled apparatus, as shown in Figure lOB with the associated electronics 113, then functions as a particle detector with improved spati~l resolution. One advantage of this third embodiment is that the first and second sets of layers may be fabricated independently. If a high temperature is needed to fabricate the columnar luminescent layar 107, the photodiodP layer 103 is fabricated separately and is not subjected to this high temperature. Readout electronics is also present, but not shown, in Figures 2, 3, 9 and 10B.
Example~ The following procedure is preferred for producing a ridge pattern in a polyimide layer. The substrat:e used should be rinsed in de-ionized water at a temperature of T = 80C for a time interval ~t = 3 -10 minutes. Polyimide material, such as DuPont PI
2555, is spun on an exposed surface of the substrate at a rotation rate of about 3500 rpm for a time interval ~t = 30 sec, or for a time sufficient to produce a polyimide layer of an approximate thickness of 3.5 ~m.
Alternatively, DuPont PI 2722 material, which contains both the polyimide and a photoresist material, may be used in place of the PI 2555 material. The substrate-polyimide layer combination is then softbaked for about 3 min at a temperature T = 90C.
Photoresist, such as KTI 820, is then spun on top of the polyimide layer at a rotation speed of about 3500 rp~ for a time interval.~t = 30 secj or for a time ; ~ufficient-to produce aiphotoresist thickness of 2.5 -3.4 ~m. The ~ubstrate-polyimide layer-photoresist layer is~then softbaked for 2 min. at-a temperature T
= 120C.!- - The- photoresist is then exposed to ultraviolet radiation in the desired pattern for about 15 sec, using photolithography equipment and procedures known in the art. The irradiated photoresist is then baked for about 60 sec. and is devaloped. The ~W093/0~96. -15- 2f ~?~ ~ PcT~us92/o63o8 photoresist is immersed in a suitable developer, such as Kodak 934, for about 120 sec., then rinsed and dried. The polyimide is etched simultaneously when the photoresist is developed. The resulting ridge structure is then hardbaked or cured for at least one hour at a temperature of T = 280C, or for one half hour at T = 350C. The scintillation layer material is then coated on the ridge structure to the desired thickness d4 = 100 - 1,000 ~m, using a low evaporation rate to allow columns of scintillation material to ~orm in conformity to the ridge pattern provided.
Figure 11 is a graphical view illustrating the improvement in spatial resolution, using the invention in one embodiment. The solid circles represent 15 intensity of light received through a conventional, unstructured layer of CsI of thickness 450 ~m with an a-Si:H photodiode layer and have an associated FWHM of 540 ~m about a selected central position at x = 1,500 ~m.. The triangles represent intensity of light received through a columnar structure of 450 ~m thick CsI, fa~ricated according to the invention, with an a-Si:H~photodiode layer in tbe same configuration.
Here, the FWHM is 230 ~m, a reduction of about 58 percent in the point spread width in one dimension; in two dimensions, the point spread width reduction is estimated to be about 72 percent. A particle detector constructed-using-the invention disclosed`here may i:~resolve:.lateral spa~ial eeparations-às smal~l-as lo - 50 30 ..~he gaps 20~or 91 or-109 in Figures 1, 2,~9 or lOA/lOB
may be filled, by~capillary action or otherwise, with a light-absorbing material, -such` as Te, Sb or Sn (useful for CsI), to reduce the point spread factor associated with light produced in a luminescent layer column fabricated according to the invention. Using ,. w093/0~96 2;1 1 4 ~ 3 9 -16- PCT/US92/~30g ~, this embodiment, most of the light that is not internally reflected within a given column is absorbed by the material in an adjacent gap and does not appear in another such column. This will reduce the total amount of light produced and transmitted by the luminescent layer but will improve the spat,,ial resolution by ensuring that substantially all light produced in a given column of luminescent material will either be absorbed or will propagate within that column to the photodiode layer, where associated rea~out electronics 22 (Figure 1) detects which column of luminescent material produced the material. ~ The absorbing material used here should have an optical absorpt:ion edge that reaches its maximum near, but below, the range of wavelengths produced by the luminescent material.
It is advantageous in the inventive method to provide interstitial material in the gaps between the cylinders or column ætructures which comprise the scintillation layer of,the inventive detector. Spatial resolution can be improved by from 10% to 30% using this approach.
The iinter~titial material~,serves a variety of functions, including increasing structural integrity of the scintillation layer and improving the sensitivity of the detection capability.
,.-Interstitial, material increases~the sensitivity of ~, detection .by limiting,the intercolumnar. transfer.i of light, particles, heat, and other factors. .:!.For instance, low energy X-rays are typically generated in the columns. These;. will o~ten be emitted from the ... column wall,,-,gener.,a,lly at an.incident angle., When,this .- occurs, the low energy X-rays commonly impact adjacent . columns, inducing cross talk in the detector of the -. adjacent column. This background signal lessens the acuity of the resulting detector, and compromises its ~W093/03496 17- ? `
acuity of the resulting detector, and compromises its spatial resolution.
Scintillation layer light generation which occurs at the periphery of the columnar surface or communicates to the interstitial areas also is a source of background noise. For instance, light which escapes internal reflection may enter an adjacent column, or even scatter farther afield of the actual point of production. As such, it will give a false reading as to the spatial position of the particle impact.
The ill effects of random light scatter and detection of errant low energy X-rays can be limited or fully ameliorated by the use of interstitial materials. The choice of the material depends on a compromise between the desired results and ease of application. For instance, a multipurpose material would absorb both light and X-rays. Even if such a material did not have optimum qualities in both these functions, if it can perform both to a reasonable level it may be the material of choice. Examples of such multipurpose materials are Tl2O and WC16~
,; - , :
For light attenuation, it is useful to provide an interstitial material that absorbs light in the range of 300-700 nm in wave length. Alternatively,- the intersti*ial material may-be reflective ~-in nature.
~e This has the advantage of returning the~light signal to :the-appropriatel!column.-~ The use of- such- materials ~allows the possibility of the light being correctly redirected through the column thus preventing a reading error.~
Appropriate candidates for light absorbing interstitial materials are various dyes and inks, Dykem Blue, Sr. W~ 93/0~96 2 ~ PCT/US92/06308 ~ -18-mercury and its salts, metals and their alloys, iodine and the like.
Interstitial material should have the capacity to absorb low energy X-rays produced within columns and capa~le of reaching adjacent columns. This quality is exemplified by a hi~h density and a high Z value, preferably above 50. Mercury has high Z value and high density, and so is an excellent absorber of errant low energy X-rays. Mercury salts would have similar capacities. At a Z value of 50, iodine is in an acceptable range of X-ray absorption capability;
:, Various methods for depositing the desired material in the interstitial areas of the scintillation layer are availab.le. Two useful methods are vapor deposition and application through a solute carrier. Common objectives of these two methods are to achieve uniformity of layer deposition, fuIl penetration of the interstitial area, and excellent adhesion of the layer to the substrate.
.: .; ., , Vapor deposition must occur at a temperature which will not damage various components of the detector. In one example of the present invention, the cesium iodide . layer is the limiting material in this regard.
Therefore, :~ materials ~ selected for evaporation 25.:deposition in this case.:must have. an.~evaporation temperature of- less than.650~degrees Celsius.~. Good ..candidates.-for.this process are..thus.mercury~,.with.an .evaporation. temperature of 365.degrees Celsius, and . iodine, with an:evaporation.temperature of less than 200 degrees Celsius. Various organic and inorganic compounds will also be usefuI in the vapor deposition process.
.
.`` wo g3/0~96 ` 2 1 11'~ 5~ i PCr/US92/06308 ~ ~ --19--Vapor deposition is accomplished by confining the scintillator and the interstitial material within an enclosed vessel. The interstitial material is then evaporated, and recondensed on the substrate sur~ace and interstitial area. In most cases, the material is heated to provide the necessary evaporation. The su~strate is preferably heated to increase wetting and creep effects, and to improve adherence. A higher quality deposition in a shorter period of time is achieved compared to a system where the substrate is not heated. Typically, the entire treatment chamber is warmed to avoid preferential deposition on the c~amber wall.
As a rule, the more gradual the heating and subsequent coolingl, the finer the quality of the resultant deposited layer. Placing the substrate towards the top of the chamber avoids droplets of precipitating interstitial material should the chamber become supersal:urated. One wishes to avoid the ~ormation of liquid on the surface of the substrate prior to the filling of the interstitial areas. ~ Processing parameters~ can be modified to assure that the condensation occurs uniformly within the columnar intersticial regions.
The- interstitial area can also be filled using !~materials dissolved or suspended in a liquid carrier.
---In the-case:of the presently described materials, water~
''!~',' asra olvent is;counter-indicated because of its ill effect on the inventive materials. Useful solvents in this regard are non-aqueous materials such as acetone, carbon tetrachloride, anhydrous alcohols and the like.
While a solution close to saturation with the material to be deposited is generally preferred, this consideration must be balanced by the ill effects of a - . .:
1 W093/0~96 21~..5~ PCT/U~92/~ ~8 ' -20~
viscous solution. Some amount of heating is possible to alleviate this problem.
Appropriate solutions for treatment of the inventive scintillation layers are iodine dissolved in anhydrous methyl or higher alcohols, or commercial dye mater,ials such as organic inks. Sequential dipping and five minute drying produces an excellent result with these materials.
A required finishing step is common to both the vapor deposition and the solution deposition processes. If filling of the interstices to the surface level is to be assured, deposition must also be allowed on the surface. However, in the functioning detector, this layer must be removed. There are many methods available for removing this surface coating, including chemical dissolution and mechanical abrasion.
Solvent removal of the surface film must be approached with care to avoid damage of the interstitial deposits.
Typically, the solvent is provided in an absorbent material, such as a blotter, and wiped across the surface. This is done only until visual observation indicates removal of the undesired film.
Mechanical abrasion can also be used to remove the ~excess film layer. Simple sanding,or scraping will 25",--of~ten,surface for-the-needs~of the-present invention.
This may have-an advantageous effect of preparing the surface~for application of additional components.
Claims
Claims 1. A method of producing a detector of X-rays and high energy charged particles with improved spatial resolution, the method comprising the steps of:
providing a substrate layer of material with an electrically conductive surface;
forming a particle detector layer containing a-Si:H, a-Ge:H, or other appropriate amorphous semiconductor material on the conductive surface of the substrate layer;
forming a conductive layer of electrically conductive material that is at least partly transparent to incident light having a wavelength .lambda. in the range 0.3 µm ? .lambda. ? 0.7 µm, adjacent to the particle detector layer so that the particle detector layer lies between the substrate layer and the conductive layer;
forming a pattern formation layer, having at least a predetermined minimum thickness and containing an etchable material, adjacent to the conductive layer so that the conductive layer lies between the particle detector layer and the pattern formation layer;
etching a predetermined pattern in the pattern formation layer so that the etchable material forms a plurality of ridges or projections, of lateral width d, on an exposed surface of the pattern formation layer;
and forming a scintillation layer, at a growth rate ?
500 µm per hour, at a temperature T in the range 50°C
? T ? 400°C, and of thickness no more than 100 d, of scintillation material that produces light of wavelength in the range 0.3 - 0.7 µm in response to receipt of high energy particles thereat, whereby the scintillation material forms as cylinders or columns, separated by gaps that conform to the predetermined pattern.
2. The method of claim 1, further comprising the step of choosing said scintillation layer material from the class consisting of CsI, KI, RbI, CdS, ZnxCd1-xS, Gd2O2S, La2O2S, GaySe, CdWO3 and PbO2.
3. The method of claim 1, further comprising the step of choosing said conductive layer material from the class consisting of ITO, TO, Al, Cr, Au, Ag, Pd and Pt.
4. The method of claim 1, further comprising the step of choosing said pattern formation layer material from the class consisting of polyimide, amorphous silicon, crystalline silicon, amorphous germanium, crystalline germanium, or metals such as Al, Cr, Au, Ag, Pt and Pd..
5. The method of claim 4, further comprising the step of choosing said predetermined pattern for said pattern formation layer from the class consisting of a triangle, a quadrilateral, a hexagon, an oval and a linear array pattern.
6. The method of claim 1, further comprising the step of filling said gaps between said columns with a material.
7. The method of claim 1, further comprising the step of choosing said scintillation layer growth rate to be no more than 250 µm per hour.
8. The method of claim 1, further comprising the step of choosing said temperature T to lie in the range 100°C ? T ? 250°C.
9. The method of claim 1, further comprising the step of choosing said thickness of said scintillation layer to be no more than 50 d.
10. The method of claim 1, further comprising the step of choosing said lateral width d to be in the range 2-20 µm.
11. A method of producing a detector of X-rays and high energy charged particles with improved spatial resolution, the method comprising the steps of:
providing a substrate layer of material having an electrically conductive surface and containing an etchable material;
etching a predetermined pattern in the conductive surface of the substrate so that the etchable material forms a plurality of projections of lateral width d on the conductive surface of the substrate surface;
forming a scintillation layer, at a growth rate ?
500 µm per hour, at a temperature T in the range 50°C
? T ? 400°C, and of thickness no more than 100 d, of scintillation material that produces light of wavelength .lambda. in the range 0.3 µm ? .lambda. ? 0.7 µm in response to receipt of high energy particles thereat;
forming a thin layer of sealant material on an exposed surface of the scintillation layer so that the scintillation layer lies between the substrate layer and the etchable material layer;
forming a conductive layer of electrically conductive material that is at least partly transparent to incident light having a wavelength lying in the range 0.3 µm ? .lambda. ? 0.7 µm, adjacent to an exposed surface of the sealant material layer so that the sealant material layer lies between the scintillation layer and the conductive layer;
forming a particle detection layer adjacent to an exposed surface of the conductive layer and containing a-Si:H, a-Ge:H, or other appropriate amorphous semiconductor material;
whereby the scintillation material forms as cylinders or columns, separated by gaps that conform to the predetermined pattern.
12. The method of claim 11, further comprising the step of choosing said scintillation layer material from the class consisting of CsI, KI, RbI, CdS, ZnxCd1-xS, Gd2O2S, La2O2S, GaySe, CdWO3 and PbOz.
13. The method of claim 11, further comprising the step of choosing said conductive layer material from the class consisting of ITO, TO, Al, Cr, Au, Ag, Pd and Pt.
14. The method of claim 11, further comprising the step of choosing said pattern formation layer material from the class consisting of polyimide, amorphous silicon, crystalline silicon, amorphous germanium, crystalline germanium, or metals such as Al, Cr, Au, Ag, Pt or Pd.
15. The method of claim 14, further comprising the step of choosing said predetermined pattern for said pattern formation layer from the class consisting of a triangle, a quadrilateral, a hexagon, an oval and a linear array pattern.
16. The method of claim 11, further comprising the step of filling said gaps between said columns with a material.
18. The method of claim 11, further comprising the step of choosing said temperature T to lie in the range 100°C ? T ? 250°C.
19. The method of claim 11, further comprising the step of choosing said thickness of said scintillation layer to be no more than 50 d.
20. The method of claim 11, further comprising the step of choosing said lateral width d to be in the range 2-20 µm.
21. A method of producing a detector of X-rays and high energy charged particles with improved spatial resolution, the method comprising the steps of:
forming a first structural component consisting of a first substrate layer of material and a particle detector layer, containing a-Si:H, a-Ge:H, or other appropriate amorphous semiconductor material and deposited on an exposed surface of the first substrate layer;
forming a second structural component by:
forming a second substrate layer of material containing an etchable material on an exposed surface;
etching a. predetermined pattern in the etchable material of the second substrate layer to form a plurality of ridges or projections, of lateral width d, on an exposed surface of the etchable material; and forming a scintillation layer, at a growth rate ? 500 µm per hour, at a temperature T in the range 50°C ? T ? 400°C, and of thickness no more than 100 d, of-scintillation material that produces light having a wavelength .lambda. lying in the range 0.3 µm ? .lambda. ? 0.7 µm in response to receipt of high energy particles, so that the scintillation material forms as cylinders or columns, separated by gaps that conform to the predetermined pattern; and bringing the first and second structural components together so that an exposed surface of the particle detection layer is adjacent to an exposed surface of the scintillation layer.
22. The method of claim 21, further comprising the step of providing an optically transparent material, positioned between said scintillation layer and said particle detection layer, to hold said scintillation layer and said particle detector layer together.
23. The method of claim 21, further comprising the step of choosing said scintillation layer material from the class consisting of CsI, KI, RbI, CdS, ZnxCd1-xS, Gd2O2S, La2O2S, GaySe, CdWO3 and PbOz.
24. The method of claim 21, further comprising the step of choosing said pattern formation layer material from the class consisting of polyimide, amorphous silicon, crystalline silicon, amorphous germanium, crystalline germanium, or metals such as Al, Cr. Au, Ag, Pt, or Pd.
25. The method of claim 21, further comprising the step of choosing said predetermined pattern for said pattern formation layer from the class consisting of a triangle, a quadrilateral, a hexagon, an oval and a linear array pattern.
26. The method of claim 21, further comprising the step of filling said gaps between said columns with a material.
27. The method of claim 21, further comprising the step of choosing said scintillation layer growth rate to be no more than 250 µm per hour.
28. The method of claim 21, further comprising the step of choosing said temperature T to lie in the range 100°C ? T ? 250°C.
29. The method of claim 21, further comprising the step of choosing said thickness of said scintillation layer to be no more than 50 d.
30. The method of claim 21, further comprising the step of choosing said lateral width d to be in the range 2-20 µm.
31. Apparatus for detection of X-rays and high energy charged particles with improved spatial resolution of detection, the apparatus comprising:
a first substrate, having an electrically conductive surface;
a particle detector layer, formed on the conductive surface of the first substrate;
an electrically conductive layer, formed on an exposed surface of the particle detector layer;
a scintillation layer, formed on an exposed surface of the conductive layer as a plurality of columns of scintillation material that produces light having a wavelength .lambda. lying in a range 0.3 µm ? .lambda. ? 0.7 µm in response to receipt of high energy particles, with adjacent columns of scintillation material being separated by gaps of maximum lateral width d and the columns of scintillation material having a height no more than 100 d; and a sealant layer, formed over an exposed surface of the scintillation layer, where the gaps between the columns of luminescent material conform to a predetermined pattern at the interface between the conductive layer and the luminescent layer, or at the interface between the sealant layer and the luminescent layer.
32. The apparatus of claim 31, wherein said scintillation layer material is drawn from the class consisting of CsI, KI, RbI, CdS, ZnxCd1-xS, Gd2O2S, La2O2S, GaySe, CdWO3 and PbOz.
33. The apparatus of claim 31, wherein said predetermined pattern is drawn from the class consisting of a triangle, a quadrilateral, a hexagon, an oval and a linear array pattern.
34. The apparatus of claim 31, wherein said height of said columns of said scintillation material is no more than 50 d.
35. The method of Claim 6, wherein the material absorbs or reflects light and/or subatomic particles.
36. The method of Claim 35, wherein the material absorbs light in the range of 300-700 nm.
37. The method of Claim 35, wherein the material is dense and has a high Z value.
38. The method of Claim 35, wherein the material is selected from the group comprising dyes, inks, metals and their alloys, organic compounds and inorganic compounds.
39. The method of Claim 38, wherein the material is selected from the group comprising Dykem Blue, iodine, TlO2, WCl6, and mercury and its salts.
40. The method of Claim 6, wherein the-material is deposited using vapor deposition.
41. The method of Claim 6, wherein the material is deposited in a solute.
42. The method of Claim 16, wherein the material absorbs or reflects light and/or subatomic particles.
43. The method of Claim 42, wherein the material absorbs light in the range of 300-700 nm.
44. The method of Claim 42, wherein the material is dense and has a high Z value.
45. The method of Claim 42, wherein the material is selected from the group comprising dyes, inks, metals and their alloys, organic compounds and inorganic compounds.
46. The method of Claim 45, wherein the material is selected from the group comprising Dykem Blue, iodine, TlO2, WCl6, and mercury and its salts.
47. The method of Claim 16, wherein the material is deposited using vapor deposition.
48. The method of Claim 16, wherein the material is deposited in a solute.
49. The method of Claim 26, wherein the material absorbs or reflects light and/or subatomic particles.
50. The method of Claim 49, wherein the material absorbs light in the range of 300-700 nm.
51. The method of Claim 49, wherein the material is dense and has a high Z value.
52. The method of Claim 49, wherein the material is selected from the group comprising dyes, inks, metals and their alloys, organic and inorganic compounds.
53. The method of Claim 52, wherein the material is selected from the group comprising Dykem Blue, iodine, TlO2, WCl6, and mercury and its salts.
54. The method of Claim 26, wherein the material is deposited using vapor deposition.
55. The method of Claim 26, wherein the material is deposited in a solute.
providing a substrate layer of material with an electrically conductive surface;
forming a particle detector layer containing a-Si:H, a-Ge:H, or other appropriate amorphous semiconductor material on the conductive surface of the substrate layer;
forming a conductive layer of electrically conductive material that is at least partly transparent to incident light having a wavelength .lambda. in the range 0.3 µm ? .lambda. ? 0.7 µm, adjacent to the particle detector layer so that the particle detector layer lies between the substrate layer and the conductive layer;
forming a pattern formation layer, having at least a predetermined minimum thickness and containing an etchable material, adjacent to the conductive layer so that the conductive layer lies between the particle detector layer and the pattern formation layer;
etching a predetermined pattern in the pattern formation layer so that the etchable material forms a plurality of ridges or projections, of lateral width d, on an exposed surface of the pattern formation layer;
and forming a scintillation layer, at a growth rate ?
500 µm per hour, at a temperature T in the range 50°C
? T ? 400°C, and of thickness no more than 100 d, of scintillation material that produces light of wavelength in the range 0.3 - 0.7 µm in response to receipt of high energy particles thereat, whereby the scintillation material forms as cylinders or columns, separated by gaps that conform to the predetermined pattern.
2. The method of claim 1, further comprising the step of choosing said scintillation layer material from the class consisting of CsI, KI, RbI, CdS, ZnxCd1-xS, Gd2O2S, La2O2S, GaySe, CdWO3 and PbO2.
3. The method of claim 1, further comprising the step of choosing said conductive layer material from the class consisting of ITO, TO, Al, Cr, Au, Ag, Pd and Pt.
4. The method of claim 1, further comprising the step of choosing said pattern formation layer material from the class consisting of polyimide, amorphous silicon, crystalline silicon, amorphous germanium, crystalline germanium, or metals such as Al, Cr, Au, Ag, Pt and Pd..
5. The method of claim 4, further comprising the step of choosing said predetermined pattern for said pattern formation layer from the class consisting of a triangle, a quadrilateral, a hexagon, an oval and a linear array pattern.
6. The method of claim 1, further comprising the step of filling said gaps between said columns with a material.
7. The method of claim 1, further comprising the step of choosing said scintillation layer growth rate to be no more than 250 µm per hour.
8. The method of claim 1, further comprising the step of choosing said temperature T to lie in the range 100°C ? T ? 250°C.
9. The method of claim 1, further comprising the step of choosing said thickness of said scintillation layer to be no more than 50 d.
10. The method of claim 1, further comprising the step of choosing said lateral width d to be in the range 2-20 µm.
11. A method of producing a detector of X-rays and high energy charged particles with improved spatial resolution, the method comprising the steps of:
providing a substrate layer of material having an electrically conductive surface and containing an etchable material;
etching a predetermined pattern in the conductive surface of the substrate so that the etchable material forms a plurality of projections of lateral width d on the conductive surface of the substrate surface;
forming a scintillation layer, at a growth rate ?
500 µm per hour, at a temperature T in the range 50°C
? T ? 400°C, and of thickness no more than 100 d, of scintillation material that produces light of wavelength .lambda. in the range 0.3 µm ? .lambda. ? 0.7 µm in response to receipt of high energy particles thereat;
forming a thin layer of sealant material on an exposed surface of the scintillation layer so that the scintillation layer lies between the substrate layer and the etchable material layer;
forming a conductive layer of electrically conductive material that is at least partly transparent to incident light having a wavelength lying in the range 0.3 µm ? .lambda. ? 0.7 µm, adjacent to an exposed surface of the sealant material layer so that the sealant material layer lies between the scintillation layer and the conductive layer;
forming a particle detection layer adjacent to an exposed surface of the conductive layer and containing a-Si:H, a-Ge:H, or other appropriate amorphous semiconductor material;
whereby the scintillation material forms as cylinders or columns, separated by gaps that conform to the predetermined pattern.
12. The method of claim 11, further comprising the step of choosing said scintillation layer material from the class consisting of CsI, KI, RbI, CdS, ZnxCd1-xS, Gd2O2S, La2O2S, GaySe, CdWO3 and PbOz.
13. The method of claim 11, further comprising the step of choosing said conductive layer material from the class consisting of ITO, TO, Al, Cr, Au, Ag, Pd and Pt.
14. The method of claim 11, further comprising the step of choosing said pattern formation layer material from the class consisting of polyimide, amorphous silicon, crystalline silicon, amorphous germanium, crystalline germanium, or metals such as Al, Cr, Au, Ag, Pt or Pd.
15. The method of claim 14, further comprising the step of choosing said predetermined pattern for said pattern formation layer from the class consisting of a triangle, a quadrilateral, a hexagon, an oval and a linear array pattern.
16. The method of claim 11, further comprising the step of filling said gaps between said columns with a material.
18. The method of claim 11, further comprising the step of choosing said temperature T to lie in the range 100°C ? T ? 250°C.
19. The method of claim 11, further comprising the step of choosing said thickness of said scintillation layer to be no more than 50 d.
20. The method of claim 11, further comprising the step of choosing said lateral width d to be in the range 2-20 µm.
21. A method of producing a detector of X-rays and high energy charged particles with improved spatial resolution, the method comprising the steps of:
forming a first structural component consisting of a first substrate layer of material and a particle detector layer, containing a-Si:H, a-Ge:H, or other appropriate amorphous semiconductor material and deposited on an exposed surface of the first substrate layer;
forming a second structural component by:
forming a second substrate layer of material containing an etchable material on an exposed surface;
etching a. predetermined pattern in the etchable material of the second substrate layer to form a plurality of ridges or projections, of lateral width d, on an exposed surface of the etchable material; and forming a scintillation layer, at a growth rate ? 500 µm per hour, at a temperature T in the range 50°C ? T ? 400°C, and of thickness no more than 100 d, of-scintillation material that produces light having a wavelength .lambda. lying in the range 0.3 µm ? .lambda. ? 0.7 µm in response to receipt of high energy particles, so that the scintillation material forms as cylinders or columns, separated by gaps that conform to the predetermined pattern; and bringing the first and second structural components together so that an exposed surface of the particle detection layer is adjacent to an exposed surface of the scintillation layer.
22. The method of claim 21, further comprising the step of providing an optically transparent material, positioned between said scintillation layer and said particle detection layer, to hold said scintillation layer and said particle detector layer together.
23. The method of claim 21, further comprising the step of choosing said scintillation layer material from the class consisting of CsI, KI, RbI, CdS, ZnxCd1-xS, Gd2O2S, La2O2S, GaySe, CdWO3 and PbOz.
24. The method of claim 21, further comprising the step of choosing said pattern formation layer material from the class consisting of polyimide, amorphous silicon, crystalline silicon, amorphous germanium, crystalline germanium, or metals such as Al, Cr. Au, Ag, Pt, or Pd.
25. The method of claim 21, further comprising the step of choosing said predetermined pattern for said pattern formation layer from the class consisting of a triangle, a quadrilateral, a hexagon, an oval and a linear array pattern.
26. The method of claim 21, further comprising the step of filling said gaps between said columns with a material.
27. The method of claim 21, further comprising the step of choosing said scintillation layer growth rate to be no more than 250 µm per hour.
28. The method of claim 21, further comprising the step of choosing said temperature T to lie in the range 100°C ? T ? 250°C.
29. The method of claim 21, further comprising the step of choosing said thickness of said scintillation layer to be no more than 50 d.
30. The method of claim 21, further comprising the step of choosing said lateral width d to be in the range 2-20 µm.
31. Apparatus for detection of X-rays and high energy charged particles with improved spatial resolution of detection, the apparatus comprising:
a first substrate, having an electrically conductive surface;
a particle detector layer, formed on the conductive surface of the first substrate;
an electrically conductive layer, formed on an exposed surface of the particle detector layer;
a scintillation layer, formed on an exposed surface of the conductive layer as a plurality of columns of scintillation material that produces light having a wavelength .lambda. lying in a range 0.3 µm ? .lambda. ? 0.7 µm in response to receipt of high energy particles, with adjacent columns of scintillation material being separated by gaps of maximum lateral width d and the columns of scintillation material having a height no more than 100 d; and a sealant layer, formed over an exposed surface of the scintillation layer, where the gaps between the columns of luminescent material conform to a predetermined pattern at the interface between the conductive layer and the luminescent layer, or at the interface between the sealant layer and the luminescent layer.
32. The apparatus of claim 31, wherein said scintillation layer material is drawn from the class consisting of CsI, KI, RbI, CdS, ZnxCd1-xS, Gd2O2S, La2O2S, GaySe, CdWO3 and PbOz.
33. The apparatus of claim 31, wherein said predetermined pattern is drawn from the class consisting of a triangle, a quadrilateral, a hexagon, an oval and a linear array pattern.
34. The apparatus of claim 31, wherein said height of said columns of said scintillation material is no more than 50 d.
35. The method of Claim 6, wherein the material absorbs or reflects light and/or subatomic particles.
36. The method of Claim 35, wherein the material absorbs light in the range of 300-700 nm.
37. The method of Claim 35, wherein the material is dense and has a high Z value.
38. The method of Claim 35, wherein the material is selected from the group comprising dyes, inks, metals and their alloys, organic compounds and inorganic compounds.
39. The method of Claim 38, wherein the material is selected from the group comprising Dykem Blue, iodine, TlO2, WCl6, and mercury and its salts.
40. The method of Claim 6, wherein the-material is deposited using vapor deposition.
41. The method of Claim 6, wherein the material is deposited in a solute.
42. The method of Claim 16, wherein the material absorbs or reflects light and/or subatomic particles.
43. The method of Claim 42, wherein the material absorbs light in the range of 300-700 nm.
44. The method of Claim 42, wherein the material is dense and has a high Z value.
45. The method of Claim 42, wherein the material is selected from the group comprising dyes, inks, metals and their alloys, organic compounds and inorganic compounds.
46. The method of Claim 45, wherein the material is selected from the group comprising Dykem Blue, iodine, TlO2, WCl6, and mercury and its salts.
47. The method of Claim 16, wherein the material is deposited using vapor deposition.
48. The method of Claim 16, wherein the material is deposited in a solute.
49. The method of Claim 26, wherein the material absorbs or reflects light and/or subatomic particles.
50. The method of Claim 49, wherein the material absorbs light in the range of 300-700 nm.
51. The method of Claim 49, wherein the material is dense and has a high Z value.
52. The method of Claim 49, wherein the material is selected from the group comprising dyes, inks, metals and their alloys, organic and inorganic compounds.
53. The method of Claim 52, wherein the material is selected from the group comprising Dykem Blue, iodine, TlO2, WCl6, and mercury and its salts.
54. The method of Claim 26, wherein the material is deposited using vapor deposition.
55. The method of Claim 26, wherein the material is deposited in a solute.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US07/738,529 US5171996A (en) | 1991-07-31 | 1991-07-31 | Particle detector spatial resolution |
| US738,529 | 1991-07-31 | ||
| US92150592A | 1992-07-29 | 1992-07-29 | |
| US921,505 | 1992-07-29 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2114539A1 true CA2114539A1 (en) | 1993-02-18 |
Family
ID=27113386
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002114539A Abandoned CA2114539A1 (en) | 1991-07-31 | 1992-07-30 | Improvements in particle detector spatial resolution |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0597943A4 (en) |
| JP (1) | JPH07500454A (en) |
| CA (1) | CA2114539A1 (en) |
| WO (1) | WO1993003496A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10061036B2 (en) | 2015-02-19 | 2018-08-28 | Sony Corporation | Radiation detector, method of manufacturing radiation detector, and imaging apparatus |
Families Citing this family (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5368882A (en) * | 1993-08-25 | 1994-11-29 | Minnesota Mining And Manufacturing Company | Process for forming a radiation detector |
| CA2131243A1 (en) * | 1993-09-27 | 1995-03-28 | Kenneth R. Paulson | Process for forming a phosphor |
| US5585638A (en) * | 1995-12-14 | 1996-12-17 | General Electric Company | X-ray detector for automatic exposure control of an imaging apparatus |
| GB9607209D0 (en) * | 1996-04-04 | 1996-06-12 | Eev Ltd | Detectors |
| NL1003390C2 (en) * | 1996-06-21 | 1997-12-23 | Univ Delft Tech | Planar sensor for neutron, X-ray or gamma radiation |
| US6194719B1 (en) * | 1997-06-13 | 2001-02-27 | Gatan, Inc. | Methods and apparatus for improving resolution and reducing noise in an image detector for an electron microscope |
| DE10061576A1 (en) * | 2000-12-11 | 2002-06-27 | Agfa Gevaert Ag | Storage layer and conversion layer and device for reading out X-ray information and X-ray cassette |
| DE10217426B4 (en) * | 2002-04-18 | 2006-09-14 | Forschungszentrum Jülich GmbH | Spatial detector for the measurement of electrically charged particles and use of the detector |
| DE10244177A1 (en) | 2002-09-23 | 2004-04-08 | Siemens Ag | Photosensitive screen for taking X-ray pictures has top fluorescent layer on contact layer on top of photosensor array with individual contacts on substrate with further contacts to circuit elements |
| JP5875420B2 (en) * | 2011-04-07 | 2016-03-02 | キヤノン株式会社 | Radiation detection element and manufacturing method thereof |
| JP6515958B2 (en) * | 2012-06-25 | 2019-05-22 | ソニー株式会社 | Radiation detector and method of manufacturing the same |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3783297A (en) * | 1972-05-17 | 1974-01-01 | Gen Electric | X-ray image intensifier input phosphor screen and method of manufacture thereof |
| US4011454A (en) * | 1975-04-28 | 1977-03-08 | General Electric Company | Structured X-ray phosphor screen |
| US4656359A (en) * | 1983-11-09 | 1987-04-07 | Siemens Gammasonics, Inc. | Scintillation crystal for a radiation detector |
-
1992
- 1992-07-30 WO PCT/US1992/006308 patent/WO1993003496A1/en active Search and Examination
- 1992-07-30 EP EP19920916511 patent/EP0597943A4/en not_active Withdrawn
- 1992-07-30 CA CA002114539A patent/CA2114539A1/en not_active Abandoned
- 1992-07-30 JP JP5503716A patent/JPH07500454A/en not_active Expired - Lifetime
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10061036B2 (en) | 2015-02-19 | 2018-08-28 | Sony Corporation | Radiation detector, method of manufacturing radiation detector, and imaging apparatus |
Also Published As
| Publication number | Publication date |
|---|---|
| EP0597943A1 (en) | 1994-05-25 |
| EP0597943A4 (en) | 1994-07-27 |
| WO1993003496A1 (en) | 1993-02-18 |
| JPH07500454A (en) | 1995-01-12 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US5171996A (en) | Particle detector spatial resolution | |
| CA2114539A1 (en) | Improvements in particle detector spatial resolution | |
| CN101958347B (en) | Nanostructured functional coatings and device | |
| Sivakov et al. | Roughness of silicon nanowire sidewalls and room temperature photoluminescence | |
| CA2128746C (en) | Process for forming a phosphor | |
| CN108281509B (en) | Oxide semiconductor-based photodetector and method for improving performance thereof | |
| EP0654683A2 (en) | Radiation detector | |
| US9373740B1 (en) | Wavelength converting structure for near-infrared rays and solar cell comprising the same | |
| CN107275168B (en) | A kind of novel nano structure photocathode based on titanium nitride | |
| US5981959A (en) | Pixelized scintillation layer and structures incorporating same | |
| CN103568441A (en) | Thin film super absorber with low cost and large area and preparation method of film | |
| WO2014100595A2 (en) | Apparatus, systems and methods for collecting and converting solar energy | |
| KR970010364B1 (en) | Process for forming a phospher | |
| EP0325500B1 (en) | Input screen scintillator for a radiological image intensifier tube and its manufacturing method | |
| Hutchins | Spectrally selective solar absorber coatings | |
| US4184077A (en) | Input screen of an image intensifier | |
| CN110429156A (en) | A kind of Si-APD photodetector and preparation method based on fractal nano line surface texture | |
| Benfadel et al. | Development of an antireflection layer using a LDS based on β-SiC nanoparticles | |
| GB2045283A (en) | Selective Solar Absorber | |
| JPH10319126A (en) | Radiation detector and its manufacturing method | |
| DE2829779A1 (en) | Selectively absorbent interference layer for solar energy converter - using layer of silica contg. gold particles reducing reflection of solar rays | |
| Nebol’sin et al. | Black silicon: a new manufacturing method and optical properties | |
| KR20200144617A (en) | Solar cell and manufacturing method of substrate for the solar cell | |
| Yalamanchili et al. | Highly absorbing and high lifetime tapered silicon microwire arrays as an alternative for thin film crystalline silicon solar cells | |
| FR2530368A1 (en) | Radiation-converting scintillating screen. |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |