CA1072422A - Method of producing homogeneously doped semiconductor material of p-conductivity - Google Patents
Method of producing homogeneously doped semiconductor material of p-conductivityInfo
- Publication number
- CA1072422A CA1072422A CA320,601A CA320601A CA1072422A CA 1072422 A CA1072422 A CA 1072422A CA 320601 A CA320601 A CA 320601A CA 1072422 A CA1072422 A CA 1072422A
- Authority
- CA
- Canada
- Prior art keywords
- semiconductor material
- irradiation
- gamma
- photons
- germanium
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Landscapes
- Crystals, And After-Treatments Of Crystals (AREA)
Abstract
ABSTRACT
A process for the production of substantially homogeneously doped p-conductive semiconductor material is described, which comprises subjecting the semiconductor material to be doped to irradiation with .gamma.-photons wherein the semiconductor material is germanium and wherein gallium atoms are pro-duced as doping atoms on irradiation of the germanium with .gamma.-photons.
A process for the production of substantially homogeneously doped p-conductive semiconductor material is described, which comprises subjecting the semiconductor material to be doped to irradiation with .gamma.-photons wherein the semiconductor material is germanium and wherein gallium atoms are pro-duced as doping atoms on irradiation of the germanium with .gamma.-photons.
Description
1~7Z~L~ZZ
Thepresent invention relates to a process for the production of homogeneously doped p-conductive semiconductor material and is a divisional application of Canadian Application Serial No. 233,055 filed on August 7, The doping of semiconductor material is frequently carried out(for example, in the case of silicon) during deposition of the semiconductor material from the gas phase by the thermal decornpostion of a gaseous silicon compound of silicon on a heated carrier body of the same material. During this process, doping is effected by mixing a gaseous compound of a dopant with the gaseous silicon compound, so that this also decomposes on the car-rier body. Silicon rods produced in this way are polycrystalline and must be converted into the monocrystalline state by a subsequent zone melting treatment. In this subsequent treatment, the dopant concentration often thereby changes uncontrollably and very much higher dopant concentrations must be used to ensure that the desired concentration of dopant still exists in the final product.
Germanium is frequently produced by the Czochralski crucible draw-ing method, in which a seed crystal is submerged into a germanium melt con-taining a suitable dopant and which is located in a crucible, and a mono-crystalline rod is drawn from the melt by movement of the seed crystal.Here again, the dopant is found to evaporate uncontrollably during the crys-tal growth process.
In the case of A B compounds, e.g. in the case of gallium arsenide or gallium phosphide, doping is frequently likewise effected from a melt contained in a crucible or boat.
~ hese known doping processes are time-consuming and inaccurate.
Consequently, the components produced from this semiconductor material do not possess optimal values for their electrical properties.
~s~"~, .
.
.
~7~422 It is an object of the present invention to provide a process for the production of p-conductive material by means of which it is possible to obtain a p-doping o~ a semiconductor crystal which is homogeneous throughout the crystal (e.g. in the case of a rod over the rod length and rod cross-section independent of the diameter of the rod) in a simple and economical fashion, and by means of which, in particular, very high ohmic semiconductor material can be produced. Previously this could be e~ected only with di~-ficulty using the convention processes with narrow radial and axial resis-tance tolerances.
According to the invention, there is provided a process for the production of substantially homogeneously doped p-conductive semiconductor material comprising the step of subjecting semiconductor material to be doped to irradiation with ~-photons, whereby p-doping atoms are produced in said material by a nuclear reaction or reactions initiated by the ~-photons, wherein said semiconductor material is germanium, and wherein gallium atoms are produced as doping atoms on irradiation of the germanium with ~-photons, in accordance with the nuclear reaction:
7 Ge ( ~' n) 69Ge K~ 69G
For the production of p-doped germanium, gallium is formed as the dopant by irradiation with y-photons in accordance with the nuclear reac-tion:-70Ge (Y~ n) 69Ge ~ 69Ga.
From the natural isotope 7 Ge present in the germanium, the uns-table isotope 9Ge is formed, neutrons being emitted. The 9Ge is spontaneously converted into the stable isotope 9Ga urn, nuclear reaction (K) being emitted. ~o external irradiation is required for this second s'cage.
As an example where the semiconductor material is silicon, alumin-.J
. . .
' ~7~ 2 ium atoMs are produced as dopin~ a-torns on irradiation of the silicon with y-photons, in accordance with the nuclear reaction:-28si ( y p ) >27~1 .
From the natural isotope Si contained in the silicon, the stable isotope 7Al is formed in accordance with the nuclear reaction, during which process protons are emitted.
As another example, for the production of p-doped gallium arsenide, gallium phosphide, or gallium arsenide phosphide, zinc is used as a p-dopant and is formed from the gallium by irradiating the material with y-photons, in accordance with the nuclear reaction: -9Ga (y, n) 68Ga ~ 68z From the stable isotope 9Ga, the unstable isotope Ga is formed during which process neutrons are emitted. Ga is a ~ radiator with a half-life period of 1.14 hours, and is converted into the stable isotope Zn. Here again, no external measures need to be taken to effect this transformation.
The doping concentration is dependent upon the duration of the y-radiation and the strength of the photon stream per unit of area (photon stream density). The product of the two values is referred to as the "fluence".
Thus, for example, starting with a germanium rod having a specific resistance of 47 Q cm (i.e. the intrinsic conductivity at 300 K), a desired resistance of 8.75 Q cm p~type can be produced as follows:-A 35 MeV electron beam of 100 ~A current density is arranged to strike a o.6 cm thick tungsten target. The radiation produced by the retar-dation of the electrons is used to irradiate the germanium and acts to ini-tiate the following nuclear reactions therein:-~7~2~
1 76Ge (y n) 75Ge _ ~ ~ 5As (stable) Tl/2 = 82 min-
Thepresent invention relates to a process for the production of homogeneously doped p-conductive semiconductor material and is a divisional application of Canadian Application Serial No. 233,055 filed on August 7, The doping of semiconductor material is frequently carried out(for example, in the case of silicon) during deposition of the semiconductor material from the gas phase by the thermal decornpostion of a gaseous silicon compound of silicon on a heated carrier body of the same material. During this process, doping is effected by mixing a gaseous compound of a dopant with the gaseous silicon compound, so that this also decomposes on the car-rier body. Silicon rods produced in this way are polycrystalline and must be converted into the monocrystalline state by a subsequent zone melting treatment. In this subsequent treatment, the dopant concentration often thereby changes uncontrollably and very much higher dopant concentrations must be used to ensure that the desired concentration of dopant still exists in the final product.
Germanium is frequently produced by the Czochralski crucible draw-ing method, in which a seed crystal is submerged into a germanium melt con-taining a suitable dopant and which is located in a crucible, and a mono-crystalline rod is drawn from the melt by movement of the seed crystal.Here again, the dopant is found to evaporate uncontrollably during the crys-tal growth process.
In the case of A B compounds, e.g. in the case of gallium arsenide or gallium phosphide, doping is frequently likewise effected from a melt contained in a crucible or boat.
~ hese known doping processes are time-consuming and inaccurate.
Consequently, the components produced from this semiconductor material do not possess optimal values for their electrical properties.
~s~"~, .
.
.
~7~422 It is an object of the present invention to provide a process for the production of p-conductive material by means of which it is possible to obtain a p-doping o~ a semiconductor crystal which is homogeneous throughout the crystal (e.g. in the case of a rod over the rod length and rod cross-section independent of the diameter of the rod) in a simple and economical fashion, and by means of which, in particular, very high ohmic semiconductor material can be produced. Previously this could be e~ected only with di~-ficulty using the convention processes with narrow radial and axial resis-tance tolerances.
According to the invention, there is provided a process for the production of substantially homogeneously doped p-conductive semiconductor material comprising the step of subjecting semiconductor material to be doped to irradiation with ~-photons, whereby p-doping atoms are produced in said material by a nuclear reaction or reactions initiated by the ~-photons, wherein said semiconductor material is germanium, and wherein gallium atoms are produced as doping atoms on irradiation of the germanium with ~-photons, in accordance with the nuclear reaction:
7 Ge ( ~' n) 69Ge K~ 69G
For the production of p-doped germanium, gallium is formed as the dopant by irradiation with y-photons in accordance with the nuclear reac-tion:-70Ge (Y~ n) 69Ge ~ 69Ga.
From the natural isotope 7 Ge present in the germanium, the uns-table isotope 9Ge is formed, neutrons being emitted. The 9Ge is spontaneously converted into the stable isotope 9Ga urn, nuclear reaction (K) being emitted. ~o external irradiation is required for this second s'cage.
As an example where the semiconductor material is silicon, alumin-.J
. . .
' ~7~ 2 ium atoMs are produced as dopin~ a-torns on irradiation of the silicon with y-photons, in accordance with the nuclear reaction:-28si ( y p ) >27~1 .
From the natural isotope Si contained in the silicon, the stable isotope 7Al is formed in accordance with the nuclear reaction, during which process protons are emitted.
As another example, for the production of p-doped gallium arsenide, gallium phosphide, or gallium arsenide phosphide, zinc is used as a p-dopant and is formed from the gallium by irradiating the material with y-photons, in accordance with the nuclear reaction: -9Ga (y, n) 68Ga ~ 68z From the stable isotope 9Ga, the unstable isotope Ga is formed during which process neutrons are emitted. Ga is a ~ radiator with a half-life period of 1.14 hours, and is converted into the stable isotope Zn. Here again, no external measures need to be taken to effect this transformation.
The doping concentration is dependent upon the duration of the y-radiation and the strength of the photon stream per unit of area (photon stream density). The product of the two values is referred to as the "fluence".
Thus, for example, starting with a germanium rod having a specific resistance of 47 Q cm (i.e. the intrinsic conductivity at 300 K), a desired resistance of 8.75 Q cm p~type can be produced as follows:-A 35 MeV electron beam of 100 ~A current density is arranged to strike a o.6 cm thick tungsten target. The radiation produced by the retar-dation of the electrons is used to irradiate the germanium and acts to ini-tiate the following nuclear reactions therein:-~7~2~
1 76Ge (y n) 75Ge _ ~ ~ 5As (stable) Tl/2 = 82 min-
2. 70Ge (y n) 69Ge ~ ~ 69Ga (stable) Tl/2 = 38 h.
When the irradiation is set to last for 10 mins., and after thecomplete disintegration of the radioactive isotopes produced, the following (lopant concentrations in the germanium beneath the irradiated surface are obtained :-1. 1.14 x 10 atoms As/cm3 2. 2.11 x 10 atoms Ga/cm3.Since As leads to n-doping and Ga leads to p-doping, after allowing for com-pensation 9.7 x 10 atoms Ga/cm3 remain for p-doping.
In the above example the following dopant production is required :-Starting value : 2.4 x 10 3cm 3 - 47 Q cm Target value : 2.75 x 101 cm 3 ~ 8.75 Q cm To be produced : 2.56 x 10 cm 3.
The required duration of irradiation is thus about 44 hours.
Various devices for carrying out the irradiation are known. For example~ can de Graff-generators~ cyclotrons, linear accelerators or nuclear reactors can be used for this pu~pose.
In order to heal any damage to the crystal lattice caused by ex-posure co the y-radiation, the irradiated semiconductor crystals may advan-tageously be annealed for at least one hour at a temperature above 500 C.
When the semiconductor material is silicon, the annealing can expediently be carried out in a silicon tube. The annealing step can be dispensed with, however, if the semiconductor material is to be further processed to form components and at least one high-temperature process is to be carried out during the further processing.
.
., : . .
' ~C77~Z~2~
In a part:icularly advantageous embodiment of the invention, the semiconductor material is in the form of a semiconductor rod, which is caused to rotate about its longitudinal axis during the irradiation. A poly-crystalline silicon rod having a length of 900 mm and a diameter of 35 mm may, for example, be used as the starting material. This roa is zone-melted in vacuum and subsequently or simultaneously a seed crystal having (111)-orientation is fused onto it.
In accordance with another embodiment of the invention, the semi-conductor material is in the form of a crystalline wafer and an x-y scanning of the wafer with a ~-photon beam is effected during irradiation.
r~he process of the invention makes it possible to provide silicon, germanium and gallium arsenide or gallium arsenide phosphide crystals with a homogeneous p-doping. Such crystals are particularly useful for the production of electronic semiconductor components.
r~he advantages of the process of the invention in comparison with the known doping processes are clearly shown by the greater homogeneity of -the concentra-tion of dopant in the crystal and by the avoidance of the need f'or high-temperature processes and their unfavourable consequences.
" ., !~.. .. .
', ' , ~'~, ' ~, ' .
When the irradiation is set to last for 10 mins., and after thecomplete disintegration of the radioactive isotopes produced, the following (lopant concentrations in the germanium beneath the irradiated surface are obtained :-1. 1.14 x 10 atoms As/cm3 2. 2.11 x 10 atoms Ga/cm3.Since As leads to n-doping and Ga leads to p-doping, after allowing for com-pensation 9.7 x 10 atoms Ga/cm3 remain for p-doping.
In the above example the following dopant production is required :-Starting value : 2.4 x 10 3cm 3 - 47 Q cm Target value : 2.75 x 101 cm 3 ~ 8.75 Q cm To be produced : 2.56 x 10 cm 3.
The required duration of irradiation is thus about 44 hours.
Various devices for carrying out the irradiation are known. For example~ can de Graff-generators~ cyclotrons, linear accelerators or nuclear reactors can be used for this pu~pose.
In order to heal any damage to the crystal lattice caused by ex-posure co the y-radiation, the irradiated semiconductor crystals may advan-tageously be annealed for at least one hour at a temperature above 500 C.
When the semiconductor material is silicon, the annealing can expediently be carried out in a silicon tube. The annealing step can be dispensed with, however, if the semiconductor material is to be further processed to form components and at least one high-temperature process is to be carried out during the further processing.
.
., : . .
' ~C77~Z~2~
In a part:icularly advantageous embodiment of the invention, the semiconductor material is in the form of a semiconductor rod, which is caused to rotate about its longitudinal axis during the irradiation. A poly-crystalline silicon rod having a length of 900 mm and a diameter of 35 mm may, for example, be used as the starting material. This roa is zone-melted in vacuum and subsequently or simultaneously a seed crystal having (111)-orientation is fused onto it.
In accordance with another embodiment of the invention, the semi-conductor material is in the form of a crystalline wafer and an x-y scanning of the wafer with a ~-photon beam is effected during irradiation.
r~he process of the invention makes it possible to provide silicon, germanium and gallium arsenide or gallium arsenide phosphide crystals with a homogeneous p-doping. Such crystals are particularly useful for the production of electronic semiconductor components.
r~he advantages of the process of the invention in comparison with the known doping processes are clearly shown by the greater homogeneity of -the concentra-tion of dopant in the crystal and by the avoidance of the need f'or high-temperature processes and their unfavourable consequences.
" ., !~.. .. .
', ' , ~'~, ' ~, ' .
Claims (5)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for the production of substantially homogeneously doped p-conductive semiconductor material comprising the step of subjecting semiconductor material to be doped to irradiation with .gamma.-photons, whereby p-doping atoms are produced in said material by a nuclear reaction or reac-tions initiated by the .gamma.-photons, wherein said semiconductor material is germanium, and wherein gallium atoms are produced as doping atoms on irradi-ation of the germanium with .gamma.-photons, in accordance with the nuclear reac-tion:
.
.
2. A process as claimed in claim 1, wherein the doping concentration produced is determined by selection of the duration of irradiation and the density of the .gamma.-photon stream per unit area.
3. A process as claimed in claim 1, wherein, in order to heal any damage to the crystal lattice caused by irradiation, the irradiated semi-conductor material is annealed for at least one hour at a temperature above 500°C.
4. A process as claimed in claim 1, wherein said semiconductor material is in the form of a rod, which is caused to rotate about its longi-tudinal axis during the irradiation step.
5. A process as claimed in claim 1, wherein said semiconductor material is in the form of a crystalline wafer, and wherein an x-y scanning of the wafer with a.gamma.-photon beam is effected during irradiation.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA320,601A CA1072422A (en) | 1974-08-16 | 1979-01-31 | Method of producing homogeneously doped semiconductor material of p-conductivity |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE2439430A DE2439430C2 (en) | 1974-08-16 | 1974-08-16 | Process for the production of homogeneously doped semiconductor material with p-conductivity |
| CA233,055A CA1068583A (en) | 1974-08-16 | 1975-08-07 | Method of producing homogeneously doped semiconductor material of p-conductivity |
| CA320,601A CA1072422A (en) | 1974-08-16 | 1979-01-31 | Method of producing homogeneously doped semiconductor material of p-conductivity |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1072422A true CA1072422A (en) | 1980-02-26 |
Family
ID=27164067
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA320,601A Expired CA1072422A (en) | 1974-08-16 | 1979-01-31 | Method of producing homogeneously doped semiconductor material of p-conductivity |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1072422A (en) |
-
1979
- 1979-01-31 CA CA320,601A patent/CA1072422A/en not_active Expired
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| De Kock et al. | The effect of doping on the formation of swirl defects in dislocation-free Czochralski-grown silicon crystals | |
| US4684413A (en) | Method for increasing the switching speed of a semiconductor device by neutron irradiation | |
| US3967982A (en) | Method of doping a semiconductor layer | |
| CA1068583A (en) | Method of producing homogeneously doped semiconductor material of p-conductivity | |
| CN113215662A (en) | Gallium arsenide crystal and gallium arsenide crystal substrate | |
| US4135951A (en) | Annealing method to increase minority carrier life-time for neutron transmutation doped semiconductor materials | |
| US3076732A (en) | Uniform n-type silicon | |
| Gaiduk et al. | Discontinuous tracks in arsenic-doped crystalline Si 0.5 Ge 0.5 alloy layers | |
| US4027051A (en) | Method of producing homogeneously doped n-type Si monocrystals and adjusting dopant concentration therein by thermal neutron radiation | |
| CA1072422A (en) | Method of producing homogeneously doped semiconductor material of p-conductivity | |
| US4042454A (en) | Method of producing homogeneously doped n-type Si monocrystals by thermal neutron radiation | |
| CA1072423A (en) | Method of producing homogeneously doped semiconductor material of p-conductivity | |
| Von Ammon | Neutron transmutation doped silicon—technological and economic aspects | |
| SU717999A3 (en) | Method of alloying silicon monocrystals | |
| EP3675155A1 (en) | Recombination lifetime control method | |
| Williams | Subsurface processing of electronic materials assisted by atomic displacements | |
| WO2023199954A1 (en) | Method for manufacturing impurity-doped semiconductor | |
| Ciszek | Growth of 40 mm diameter silicon crystals by a pedestal technique using electron beam heating | |
| RU2202655C1 (en) | Method of production of resistive silicon | |
| US11551932B2 (en) | Photonuclear transmutation doping in gallium-based semiconductor materials | |
| Kolkovskii et al. | The effect of grown‐in structural imperfections on the radiation defect formation and annealing in dislocation‐free silicon | |
| RU2145128C1 (en) | Method for producing n-type nuclear-doped silicon (options) | |
| KR100329718B1 (en) | A DOPING METHOD OF GaN WAFER AND A DOPED GaN WAFER | |
| Findlay et al. | Photonuclear transmutation doping of semiconductors | |
| Dutta et al. | Bulk growth of GaSb and Ga 1-x In x Sb |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |