US4082889A — Luminescent material, luminescent thin film there…

Claim 1

Independent Claim 110 words

A polycrystalline semiconductor material comprising individual grains each one of which contains an impurity or impurities arranged especially such that they dope the grain to provide majority carriers of a given density distribution, said grain of semiconductor material containing dopant producing charge carriers of substantially one conductivity type, and said density of majority carriers being substantially higher in the immediate, finite region near the grain surface than in the region near the center of the grain, and said grains being of average size smaller than the minority carrier diffusion length in bulk semiconductor material of the same type and doping density as the material in the center of the grain.

Claim 2

Dependent Claim 110 words

A polycrystalline semiconductor material comprising individual grains each one of which contains an impurity or impurities arranged especially such that they dope the grain to provide majority carriers of a given density distribution, said grain of semiconductor material containing dopant producing charge carriers of substantially one conductivity type, and said density of majority carriers being substantially higher in the immediate, finite region near the grain surface than in the region near the center of the grain, and said grains being of average size smaller than the minority carrier diffusion length in bulk semiconductor material of the same type and doping density as the material in the center of the grain.

Claim 3

Dependent Claim 24 words

Material as set forth in claim 1, in which the grain size is between about 1 and 100 microns in average cross section dimension.

Claim 4

Dependent Claim 41 words

Material as set forth in claim 1, in which the doping majority carrier density in the region of the grain boundaries is more than one order of magnitude larger than the majority carrier density in the region of the grain center.

Claim 5

Dependent Claim 28 words

Material as set forth in claim 1, in which each grain is physically separate from the other grains thereof, the material comprising essentially a powder of individual grains.

Claim 6

Dependent Claim 26 words

Material as set forth in claim 1, wherein said grains are aggregated into a film with a relatively high luminescent efficiency when excited by ionizing radiation.

Claim 7

Dependent Claim 54 words

Luminescent film as set forth in claim 5, wherein said grains are arranged contiguously to comprise a polycrystalline thin film, such that the grains are bounded either by an adjacent grain of approximately the same physical characteristics, or by the top or bottom surface of said film so that said film is electrically conductive.

Claim 8

Dependent Claim 48 words

Luminescent polycrystalline thin film comprising contiguous grains as set forth in claim 6, in which said grains comprise a material chosen from the group consisting of GaAs, GaP, AlAs, InP, AlN, and GaN, or from the group comprising alloys of any two of the materials of said group.

Claim 9

Dependent Claim 55 words

Luminescent film as set forth in claim 5, wherein said grains are arranged non-contiguously in such a way that each grain contacts the grains adjacent to itself by a small portion of the grain surface, said grains comprising a loose aggregate bound together by an inactive agent to form a mechanically and chemically stable film.

Claim 10

Dependent Claim 27 words

Luminescent film as set forth in claim 8 in which said grains comprise a material chosen from the group consisting of CdS, ZnO, ZnS, GaN, and AlN.

Claim 11

Dependent Claim 39 words

Material as set forth in claim 1, in which said semiconductor material comprises a material with a direct band gap, said material being chosen from the class including the direct band gap III-V and II-VI materials and alloys thereof.

Claim 12

Dependent Claim 29 words

Semiconductor material as set forth in claim 10 in which said III-V materials are GaP, AlN, Ga x A 1-x As and the II-VI materials are CdS and ZnS.

Claim 13

Dependent Claim 86 words

Semiconductor material as set forth in claim 11, in which the semiconductor material is N-type doped Ga x Al 1-x As, the grain size thereof being in the range from about 1 to about 10 microns, the doping density for the central portion thereof being approximately 10 17 /cm 3 , and the doping density for the region near the grain boundary thereof being approximately 10 19 /cm 3 , and the impurity dopant thereof being chosen from the group consisting of S, Se, and Te.

Claim 14

Dependent Claim 88 words

Semiconductor material as set forth in claim 11 in which said semiconductor material is GaP of substantially n-type conductivity, said grain size being in the range from about one to about 10 microns, said especial doping density profile comprising: a uniform background density of sulfur at a density of about 10 16 atoms/cm 3 ; and an additional amount of sulfur doping density reaching a maximum density of abount 10 18 atoms/cm 3 ; and said polycrystalline film having a thickness of between one micron and 20 microns.

Claim 15

Dependent Claim 85 words

An electron beam display device in which the luminescent screen thereof comprises; a polycrystalline semiconductor, said semiconductor comprising grains which are especially doped such that the doping density in the surface region of each grain is at least one order of magnitude greater than and of the same conductivity type as the doping density in the center of each grain, said semiconductor is of the direct bandgap type, and the average size of said grains is in the range from 0.5 micron to 20 microns.

Claim 16

Dependent Claim 85 words

An electron beam display device in which the luminescent screen thereof comprises; a polycrystalline semiconductor, said semiconductor comprising grains which are especially doped such that the doping density in the surface region of each grain is at least one order of magnitude greater than and of the same conductivity type as the doping density in the center of each grain, said semiconductor is of the direct bandgap type, and the average size of said grains is in the range from 0.5 micron to 20 microns.

Claim 17

Dependent Claim 17 words

A display device set forth in claim 14 in which the device is a cathode ray tube.

Claim 18

Dependent Claim 18 words

A cathode ray tube as set forth in claim 15 in whch said semiconducting film is substantially conductive.

Claim 19

Dependent Claim 31 words

A cathode ray tube as set forth in claim 16 in which said semiconductor is GaP and the doping impurity is selected from the group consisting of S, Se and Te.

Claim 20

Dependent Claim 38 words

Display device as set forth in claim 14 wherein said luminescent polycrystalline thin film comprise contiguous grains in which said grains comprise a semiconductor material chosen from the group consisting of GaAs, GaP, AlAs, InP, AlN, and GaN.

Claim 21

Dependent Claim 22 words

Display device as set forth in claim 18 wherein said grains comprise alloys of any two of the materials of said group.

Claim 22

Dependent Claim 55 words

Display device as set forth in claim 19, wherein said grains are arranged non-contiguously in such a way that each grain contacts the grains adjacent to itself by a small portion of the grain surface, said grains comprising a loose aggregate bound together by an inactive agent to form a mechanically and chemically stable film.

Claim 23

Dependent Claim 54 words

Display device as set forth in claim 20, wherein said grains are arranged contiguously to comprise a polycrystalline thin film, such that the grains are bounded either by an adjacent grain of approximately the same physical characteristics, or by the top or bottom surface of said film so that said film is electrically conductive.

Claim 24

Dependent Claim 86 words

Display device as set forth in claim 21, in which the semiconductor material is N-type doped Ga x Al 1-x As, the grain size thereof being in the range from about 1 to about 10 microns, the doping density for the central portion thereof being approximately 10 17 /cm 3 , and the doping density for the region near the grain boundary thereof being approximately 10 19 /cm 3 , and the impurity dopant thereof being chosen from the group consisting of S, Se, and Te.

Claim 25

Dependent Claim 88 words

Display device as set forth in claim 22 in which said semiconductor material is GaP of substantially n-type conductivity, said grain size being in the range from about one to about 10 microns, said especial doping density profile comprising: a uniform background density of sulfur at a density of about 10 16 atoms/cm 3 ; and an additional amount of sulfur doping density reaching a maximum density of about 10 18 atoms/cm 3 ; and said polycrystalline film having a thickness of between one microns and 20 microns.

Claim 26

Dependent Claim 47 words

Method of fabricating a polycrystalline film with a high luminous efficiency which comprises the step of: preferentially and heavily doping the region of material near the surface of each grain with a dopant of the same conductivity type as that of the substantial body of the grain.

Claim 27

Dependent Claim 47 words

Method of fabricating a polycrystalline film with a high luminous efficiency which comprises the step of: preferentially and heavily doping the region of material near the surface of each grain with a dopant of the same conductivity type as that of the substantial body of the grain.

Claim 28

Dependent Claim 53 words

Method as set forth in claim 24 in which said step for preferentially doping said regions near the grain boundary includes: a first low temperature diffusion of doping material into the grain boundaries of said film, and a second high temperature annealing of the film in which the grain boundaries have been doped.

Claim 29

Dependent Claim 47 words

Method of preferentially doping polycrystalline semiconductor material as set forth in claim 25, in which: said low temperature diffusing is accomplished at a temperature approximately between 100° C and 400° C, and said high temperature diffusing accomplished at a temperature approximately between 800° C and 1200° C.

Claim 30

Dependent Claim 63 words

Method of preferentially doping a semiconductor thin film as put forth in claim 26, in which said preferential doping of the region near the grain boundary is accomplished by: diffusing the dopant into the film at a sufficiently low temperature that grain boundary diffusion is dominant, and annealing said film at a temperature above that at which grain boundary diffusion is substantially dominant.

Claim 31

Dependent Claim 92 words

Method of fabricating a multi-grain layer of semiconductor material on an insulating substrate by the steps comprising: forming the grains of said material by deposition by a procedure selected from the group consisting of chemical vapor deposition, sputtering, vacuum evaporation, or grinding of the bulk material in which said material contains a low level of dopant material, and including a processing step of diffusing a large amount of dopant into the surface of each grain where said dopant is of the same type as the dopant of the body of the grain.

Claim 32

Dependent Claim 92 words

Method of fabricating a multi-grain layer of semiconductor material on an insulating substrate by the steps comprising: forming the grains of said material by deposition by a procedure selected from the group consisting of chemical vapor deposition, sputtering, vacuum evaporation, or grinding of the bulk material in which said material contains a low level of dopant material, and including a processing step of diffusing a large amount of dopant into the surface of each grain where said dopant is of the same type as the dopant of the body of the grain.

Claim 33

Dependent Claim 12 words

Method of claim 28 wherein said semiconductor comprises direct band gap material.

Claim 34

Dependent Claim 128 words

Method of fabricating a multi-grain layer of semiconductor material of high luminous efficiency on an insulating substrate by the steps comprising: forming the grains of said material by deposition by a procedure selected from the group consisting of chemical vapor deposition, sputtering, vacuum evaporation, or grinding of the bulk material in which said material contains a low level of dopant material, and including preferentially and heavily doping the region of material near the surface of each grain with a dopant of the same conductivity type as that of the substantial body of the grain by a processing step of diffusing a large amount of dopant into the surface of each grain where said dopant is of the same type as the dopant of the body of the grain.

Claim 35

Dependent Claim 128 words

Method of fabricating a multi-grain layer of semiconductor material of high luminous efficiency on an insulating substrate by the steps comprising: forming the grains of said material by deposition by a procedure selected from the group consisting of chemical vapor deposition, sputtering, vacuum evaporation, or grinding of the bulk material in which said material contains a low level of dopant material, and including preferentially and heavily doping the region of material near the surface of each grain with a dopant of the same conductivity type as that of the substantial body of the grain by a processing step of diffusing a large amount of dopant into the surface of each grain where said dopant is of the same type as the dopant of the body of the grain.

Claim 36

Dependent Claim 138 words

Method of fabricating a multi-grain layer of semiconductor material of high luminous efficiency on an insulating substrate by the steps comprising: forming the grains of said material by deposition by a procedure selected from the group consisting of chemical vapor deposition, sputtering, vacuum evaporation, or grinding of the bulk material in which said material contains a low level of dopant material, and including a processing step for preferentially doping said grains near said surface of each grain by diffusing a large amount of dopant into the surface of each grain where said dopant is of the same type as the dopant of the body of the grain including a first low temperature diffusion of doping material into said surfaces of said grains, and a second high temperature annealing of said layer in which said surfaces have been doped.

Claim 37

Dependent Claim 138 words

Method of fabricating a multi-grain layer of semiconductor material of high luminous efficiency on an insulating substrate by the steps comprising: forming the grains of said material by deposition by a procedure selected from the group consisting of chemical vapor deposition, sputtering, vacuum evaporation, or grinding of the bulk material in which said material contains a low level of dopant material, and including a processing step for preferentially doping said grains near said surface of each grain by diffusing a large amount of dopant into the surface of each grain where said dopant is of the same type as the dopant of the body of the grain including a first low temperature diffusion of doping material into said surfaces of said grains, and a second high temperature annealing of said layer in which said surfaces have been doped.

Claim 38

Dependent Claim 65 words

Method of fabricating said multi-grain layer as a polycrystalline film as set forth in claim 31 in which said preferential doping of the region near the grain boundary is accomplished by: diffusing the dopant into the film at a sufficiently low temperature that grain boundary diffusion is dominant, and annealing said film at a temperature above that at which grain boundary diffusion is substantially dominant.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1981-04-03	1981-10-03	1982-04-04	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1985-04-03	1985-10-03	1986-04-04	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1989-04-03	1989-10-03	1990-04-04	$7700.00	Window Closed / Lapsed

Luminescent material, luminescent thin film therefrom, and optical display device therewith

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