US2438944A - Crystal contacts of which one element is silicon - Google Patents

Crystal contacts of which one element is silicon Download PDF

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US2438944A
US2438944A US523748A US52374844A US2438944A US 2438944 A US2438944 A US 2438944A US 523748 A US523748 A US 523748A US 52374844 A US52374844 A US 52374844A US 2438944 A US2438944 A US 2438944A
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silicon
beryllium
molybdenum
chromium
crystal
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Ransley Charles Eric
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General Electric Co PLC
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
    • H01L29/40—Electrodes ; Multistep manufacturing processes therefor
    • H01L29/41—Electrodes ; Multistep manufacturing processes therefor characterised by their shape, relative sizes or dispositions
    • H01L29/417—Electrodes ; Multistep manufacturing processes therefor characterised by their shape, relative sizes or dispositions carrying the current to be rectified, amplified or switched

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  • This invention relates to electrical crystal contact devices of the type comprising a semi-conducting crystal of which silicon is a, main constituent and a metallic contact member in contact with it, the contact member commonly taking the form of a fine wire having one end pointed and biased into contact with the crystal; the invention relates also to methods of preparing the crystal of such contact devices.
  • contact devices of. the type specified are as mixers of electric oscillations of very high frequency, for example 3000 mc./s. Their efficiency for this purpose at this high frequency, and even more at still higher frequencies, increases as the capacity of the contact decreases.
  • the object of this invention is to provide crystals that yield contact devices of smaller capacity than those prepared according to the methods particularly described in the said application, or rathersince crystals resulting from apparently the same process often yield contact devices differing widely in capacity-to provide a method of making the crystals that produces a larger proportion of crystals yielding contact devices having very small capacity.
  • Chromium is generally preferable to molybdenum, because it usually enables the contact device to Withstand larger values of wavesignal power than does molybdenum.
  • the addition of chromium or molybdenum, or a mixture thereof is introduced in accordance with the invention into the silicon, which is first freed from its usual impurities, at the same time that a small quantity of beryllium or aluminium or both isintroduced into the silicon.
  • the proportion of chromium or molybdenum to silicon is one not much less, and possibly greater, than 10% by weight.
  • the additive characteristic of the invention is chromium. Little or no other change would be required if it were molybdenum or a mixture of chromium and molybdenum.
  • the additive metals are preferably introduced by melting a mixture of the pure silicon and the additive. During this process, care must be taken not to introduce undesired impurities. Those that might be derived from the air (a small quantity of oxygen is not necessarily deleterious) can be avoided by melting in. a suitable atmosphere; the most suitable we have found is a vacuum, that is to say, residual gas at a pressure of not more than 0.001 mm. of mercury. But it is difiicult or perhaps impossible to find any crucible to contain a melt that does not react slightly with the melted silicon.
  • the eutectic temperature of the aluminium-berylliumsilicon appears not to be known. It has been found that when the additive is one-quarter per cent. of aluminium, heating at 575 C. to 580 C. for several hours will produce the desired result. But if the amount of the additive is less than that corresponding to the eutectic, which will certainly be the case when the additive is beryllium, the minimum temperature may be much below the eutectic temperature; moreover there is no reason Why temperatures approaching the minimum should be used. Accordingly, these theoretical considerations are of little value as a guide to practice. Whether the additive is aluminium or beryllium or a mixture of the two (We have found one-quarter per cent. aluminium and one-half per cent.
  • a fragment of the cooled melt has a plane part of its surface highly polished by any of the processes customary among metallurgists, for example grinding with emery of increasing fineness and finally polishing with alumina-or magnesia or both.
  • the whole surface of the fragment is then dipped for 5 minutes into commercially pure 40% hydrogen fluoride diluted with an equal quantity of water.
  • the main purpose of this treatment with hydrofluoric acid is to prepare the polished surface for the subsequent oxidation; accordingly it is not necessary, though it is usually convenient, that the unpohshed part of the surface should be dipped.
  • step (5) the necessary surface oxidation is performed.
  • body resulting from step (4) is placed on a fiat silica tray (together possibly with other bodies at the same stage of preparation) and introduced into a silica tube furnace filled with air at a region thereof maintained at 1050" C.
  • a fiat silica tray together possibly with other bodies at the same stage of preparation
  • a silica tube furnace filled with air at a region thereof maintained at 1050" C.
  • the body is maintained in the said region for 2 hours and then allowed to cool.
  • An atmosphere of oxygen at a controlled pressure may be substituted for the air in the furnace; then the time of heating will depend on the pressure of oxygen.
  • step (6) the treatment given in step (4) is repeated.
  • step (7) the unpolished part must be dipped.
  • the dipping of the polished part is equally necessary, in
  • step (5) the 4 order that part of the oxide layer formed in step (5) should be removed. After the dipping, the body is washed with water.
  • a metallic layer is deposited on some or all of the unpolished surfaces.
  • the layer must not be deposited on the polished surface; accordingly this is first protected .by
  • a layer of adhesive which may be the material known as monostyrene, and pressing the polished surface against this layer.
  • the exposed unpolished surface is then coated with copper by a method described by Bedel in Comptes Rendus, vol. 192 (1931), page 802. It consists merely in dipping the surface for 5 to 10 seconds into a solution of cuprous oxide in 20% hydrofluoric acid; the copper layer deposited may be subsequently thickened by electrolysis. Copper is not deposited in tungsten or molybdenum by this process; accordingly the said rod may be conveniently of tungsten or molybdenum.
  • the coated surface is then washed and dried.
  • the body can then be mounted in a suitable metal capsule by means of solder or some other suitable low-melting alloy intervening between the metal layer and the cap sule.
  • the rod is then detached from the body and the polished surface of the body cleaned from the adhesive by washing with a suitable solvent, such as benzene or ethyl acetate.
  • the production of said silicon contact element by a process which includes the step of introducing into the silicon a determinate quantity of at least one of the two metals chromium and molybdenum, the quantity of such additive being at least of the order of 10% of the silicon.
  • the production of said silicon contact element by a process which includes the step of introducing into silicon that is substantially freed from the metallic impurities common in commercial silicon a determinate quantity of at least one of the two metals chromium and molybdenum, the quantity of such additive being at least of the order of 10% of the silicon, and a determinate relatively small quantity of at least one of the two metals aluminium and beryllium,which form a solid solution with the silicon.
  • the production of'said silicon contact element by a process which includes the step of introducing into silicon that is substantially freed from the metallic impurities common in commercial silicon a determinate quantity of at -least one of the two metals chromium and molybdenum, the quantity of such additive being at least of the order of 10% of the silicon, and a determinate quantity of at least one of the two metals aluminium and beryllium, which form a solid solution with the silicon, the quantity of such latter additive bein of the order of between /2% and 1% of the silicon.
  • an electrical crystal contact device of the kind in which the semiconducting. crystal contact element is mainly silicon
  • the production of said silicon contact element by a process which includes the steps of purifying commercial silicon so as to eliminate therefrom substantially all its common metallic impurities, and thereafter melting the purified silicon in vacuo in a crucible at least the interior surfaces of the walls of which are composed of pure beryllia, with between and of its weight of at least one of the two metals chromium and molybdenum and with enough of at least one of the two metals aluminium and beryllium to give a content of substantially /2% of the latter additive in the final product;
  • an electrical crystal contact device oi' the kind in which the semiconducting crystal contact element is mainly silicon
  • the production of said silicon contact element by a process which includes the steps of purifying commercial silicon so as to eliminate therefrom substantially all its common metallic impurities, and thereafter melting the purified silicon in vacuo in a crucible, at least the interior surfaces of the walls of which are composed of pure beryllia, with substantially 20% of chromium and with enough aluminium and beryllium to give a content of substantially 4% of each of said last two metals in the final prodnot.
  • the production of said silicon contact equent by a process which includes the steps of introducing into silicon that is substantially freed from the metallic impurities common in commercial silicon a determinate quantity of at least one of the two metals chromium and molybdenum, the quantity of such additive being at least of the order of 10% of the silicon, and a determinate quantity of at least one of the two metals aluminium and beryllium, which form a solid solution with the silicon, the quantity of such latter additive being of the order of between /2% and 1% of the silicon, polishing a plane part of the surface of a fragment of the resulting product, thereafter treating saidfragment with hydrofluoric acid, thereafter heating said fragment in an oxidising atmosphere, thereafter treating said fragment with hydrofluoric acid so as to remove some but not all of the oxide layer formed during said heating, and finally depositing a metallic layer on at least part of the unpolished surface of said fragment
  • An electrical crystal contact device including a semi-conducting crystal contact element comprised of silicon which contains a quantity, of the order of at least 10% of the silicon, of at least one of the two metals chromium and molybdenum, said element having a polished and oxidised surface, and a metallic contact element cooperating with said surface of said crystal element.
  • An electrical crystal contact device including a semi-conducting crystal contact element comprised of silicon which contains a quantity, of the order of at least 10% of the silicon, of at least one of the two metals chromium and molybdenum, together with a determinate relatively small quantity of at least one of the two metals aluminium and beryllium, said element having a polished and oxidised surface, and a metallic contact element cooperating with said surface of said crystal element.
  • An electrical crystal contact device including a semi-conducting crystal contact element comprised of silicon which is substantially free from the metallic impurities common in commercial silicon but which contains a quantity,- between substantially 10% and 20% of the weight of silicon, of at least one of the two metals chromium and molybdenum, together with a quantity, between substantially and 1% cf the weight of silicon, of at least one of the two metals aluminium and beryllium, said element having a polished and oxidised, surface, and a metallic contact element co-operating with said surface of said crystal element.
  • An electrical crystal contact device inc1uding a semi-conducting crystal contact element comprised of silicon which is substantially free from the metallic impurities common in commercial silicon but which contains substantially 20% of chromium, of aluminium and of beryllium, these percentages being of the weight of silicon, said element having a partially etched-away oxidised and polished surface, and a metallic contact element co-operating with said surface of said crystal.
  • An electrical crystal contact element comprising silicon and a quantity, of the order of at least ten per cent by weight of the silicon, of at least one of the 'tWo metals chromium and molybdenum.
  • An electrical crystal contact element comprising silicon, a quantity of the order of at least ten per cent by weight of the silicon of at least one of the two metals chromium and molybdenum, and a determinate relatively small quantity of at least one of the two metals aluminium and beryllium.
  • An electrical crystal contact element comprising silicon, a quantity between substantially ten per cent and twenty per cent by weight of the silicon of at least one of the two metals chromium and molybdenum, and a quantity between substantially one-half per cent and one per cent by weight of the silicon of at least one of the two metals aluminium and beryllium.
  • An electrical crystal contact element comprising silicon which is substantially free from the metallic impurities common in commercial silicon, twenty per cent of chromium by weight of the silicon, and one-quarter per cent of aluminium and one-quarter per cent of beryllium by weight of the silicon.
  • An electrical crystal contact element comprising silicon and a quantity of the order of at least ten per cent by weight of the silicon of at least one of the two metals chromium and molybdenum, said element having at least one polished and oxidised surface area.
  • An electrical crystal contact device comprising silicon, between substantially ten per cent and twenty per cent by weight of the silicon of at least one of the two metals chromium and molybdenum, and between substantially one-half per cent and one per cent by weight of the silicon of at least one of the two metals aluminium and beryllium, said element having at least one polished and oxidised surface area.

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  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
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Description

Patented Apr. 6, 1948 CRYSTAL CONTACTS OF WHICH ONE ELEMENT IS SILICON Charles Eric Ransley, Sudbury, England, assignor to The General Electric Company Limited,
London, England No Drawing. Application February 24, 1944, Se-
rial No. 523,748. In Great Britain March 22,
16 Claims.
This invention relates to electrical crystal contact devices of the type comprising a semi-conducting crystal of which silicon is a, main constituent and a metallic contact member in contact with it, the contact member commonly taking the form of a fine wire having one end pointed and biased into contact with the crystal; the invention relates also to methods of preparing the crystal of such contact devices.
As will presently be explained in greater detail, in the United States patent application Serial No. 454,290, filed August 10, 1942, now Patent Number 2,419,561 dated April 29, 1947, it was proposed to introduce into the silicon, freed from most or all of the impurities usually present in commercial silicon, a small proportion of aluminum or beryllium, to polish a fragment of the resulting materi'al, to treat its surface with hydrofluoric acid,
and then to subject it to a controlled oxidation. The main advantages accruing from this process are that the resulting contact devices are rendered more uniform and have greater ability to withstand without detriment larger values of power at the operating frequency.
One of the uses of contact devices of. the type specified is as mixers of electric oscillations of very high frequency, for example 3000 mc./s. Their efficiency for this purpose at this high frequency, and even more at still higher frequencies, increases as the capacity of the contact decreases. The object of this invention is to provide crystals that yield contact devices of smaller capacity than those prepared according to the methods particularly described in the said application, or rathersince crystals resulting from apparently the same process often yield contact devices differing widely in capacity-to provide a method of making the crystals that produces a larger proportion of crystals yielding contact devices having very small capacity.
This can be achieved by introducing into the silicon a considerable proportion of chromium or molybdenum, or of a mixture of chromium and molybdenum. Chromium is generally preferable to molybdenum, because it usually enables the contact device to Withstand larger values of wavesignal power than does molybdenum. Preferably the addition of chromium or molybdenum, or a mixture thereof, is introduced in accordance with the invention into the silicon, which is first freed from its usual impurities, at the same time that a small quantity of beryllium or aluminium or both isintroduced into the silicon. The proportion of chromium or molybdenum to silicon is one not much less, and possibly greater, than 10% by weight.
One embodiment of the invention will now be described by way of example. In this example the additive characteristic of the invention is chromium. Little or no other change would be required if it were molybdenum or a mixture of chromium and molybdenum.
Commercial silicon is purified, as described in the aforementioned application, by subjecting the silicon to the process described by N. P. Tucker in the Journal of the Iron and Steel Institute, vol. CXV (1), page 412, (1927). This process removes only those impurities that are not contained in the silicon crystals but occur as an additional phase, usually in the interstices between the silicon crystals. Commercial silicon is usually prepared by cooling the melt slowly; then practically all of the deleterious impurities are in the interstices and can be removed by the Tucker process. If that process fails with any sample of silicon,
it is probably because the silicon has been quenched rapidly; then the silicon should be melted and cooled slowly before it is subjected to the Tucker process. After the commercial silicon is thus purified, the additive metals are preferably introduced by melting a mixture of the pure silicon and the additive. During this process, care must be taken not to introduce undesired impurities. Those that might be derived from the air (a small quantity of oxygen is not necessarily deleterious) can be avoided by melting in. a suitable atmosphere; the most suitable we have found is a vacuum, that is to say, residual gas at a pressure of not more than 0.001 mm. of mercury. But it is difiicult or perhaps impossible to find any crucible to contain a melt that does not react slightly with the melted silicon. This diiiiculty can be overcome by using a crucible consisting of or lined with pure beryllium; for then the only impurity introduced from the crucible is beryllium, which is not harmful but beneficial. Thus, the purified commercial silicon is melted in vacuo in a beryllia crucible with 20% of its weight of chromium and with enough beryllium and alu minium to give a content of 4% beryllium and aluminium in the final product. Some of the beryllium may be derived from the crucible as previously mentioned. After the melt has been slowly cooled it is treated in the manner described in the United States patent application No. 468,577, filed December 10, 1942, now Patent No. 2,428,992 dated October 14, 1947; namely, before the solid product comprising the cooled melt is divided into pieces each suitable for a single crystal, the product is maintained for a considerable time at a temperature greatly above atmospheric temperature, but below the melting point of the product, and then quenched rapidly. The time and temperature of this heat treatment is chosen such that the additive is distributed approximately uniformly in the quenched product. theoretical grounds, it is probable that the minimum temperature at which this heat treatment will produce the desired result is that at which the additive is completely soluble in the silicon. Since the solubility of the additive is a maximum at the eutectic temperature, the minimum temperature mentioned cannot be higher than the eutectic temperature which is about 575 C. for aluminium and 1090 C. for beryllium. The eutectic temperature of the aluminium-berylliumsilicon appears not to be known. It has been found that when the additive is one-quarter per cent. of aluminium, heating at 575 C. to 580 C. for several hours will produce the desired result. But if the amount of the additive is less than that corresponding to the eutectic, which will certainly be the case when the additive is beryllium, the minimum temperature may be much below the eutectic temperature; moreover there is no reason Why temperatures approaching the minimum should be used. Accordingly, these theoretical considerations are of little value as a guide to practice. Whether the additive is aluminium or beryllium or a mixture of the two (We have found one-quarter per cent. aluminium and one-half per cent. beryllium very suitable), maintaining the product at 1050 C. for one hour and then quenching in water has been found to produce the desired uniformity. A fragment of the product is then subjected to the steps (3), (4), (5), (6), (7), of the aforementioned Patent Number 2,419,561. In the step (3) a fragment of the cooled melt has a plane part of its surface highly polished by any of the processes customary among metallurgists, for example grinding with emery of increasing fineness and finally polishing with alumina-or magnesia or both. In the further step (4) the whole surface of the fragment is then dipped for 5 minutes into commercially pure 40% hydrogen fluoride diluted with an equal quantity of water. The main purpose of this treatment with hydrofluoric acid is to prepare the polished surface for the subsequent oxidation; accordingly it is not necessary, though it is usually convenient, that the unpohshed part of the surface should be dipped.
In the further step (5) the necessary surface oxidation is performed. body resulting from step (4) is placed on a fiat silica tray (together possibly with other bodies at the same stage of preparation) and introduced into a silica tube furnace filled with air at a region thereof maintained at 1050" C. There is a definite optimum temperature for this treatment; the temperature should be observed, e. g. by a thermocouple, and kept as near 1050 C. as possible. The body is maintained in the said region for 2 hours and then allowed to cool. An atmosphere of oxygen at a controlled pressure may be substituted for the air in the furnace; then the time of heating will depend on the pressure of oxygen.
In the further step (6) the treatment given in step (4) is repeated. Now part of its object is to prepare the unpolished part for step (7) accordingly the unpolished part must be dipped. In the process now being described in detail the dipping of the polished part is equally necessary, in
For this purpose the 4 order that part of the oxide layer formed in step (5) should be removed. After the dipping, the body is washed with water.
In the further step (7) a metallic layer is deposited on some or all of the unpolished surfaces. The layer must not be deposited on the polished surface; accordingly this is first protected .by
coating the flat end of a rod with a layer of adhesive, which may be the material known as monostyrene, and pressing the polished surface against this layer. The exposed unpolished surface is then coated with copper by a method described by Bedel in Comptes Rendus, vol. 192 (1931), page 802. It consists merely in dipping the surface for 5 to 10 seconds into a solution of cuprous oxide in 20% hydrofluoric acid; the copper layer deposited may be subsequently thickened by electrolysis. Copper is not deposited in tungsten or molybdenum by this process; accordingly the said rod may be conveniently of tungsten or molybdenum. The coated surface is then washed and dried. The body can then be mounted in a suitable metal capsule by means of solder or some other suitable low-melting alloy intervening between the metal layer and the cap sule. The rod is then detached from the body and the polished surface of the body cleaned from the adhesive by washing with a suitable solvent, such as benzene or ethyl acetate.
I claim:
1. In the manufacture of an electrical crystal contact device of the kind in which the semi-conducting crystal contact element is mainly silicon, the production of said silicon contact element by a process which includes the step of introducing into the silicon a determinate quantity of at least one of the two metals chromium and molybdenum, the quantity of such additive being at least of the order of 10% of the silicon.
2. In the manufacture of an electrical crystal contact device of the kind in which the semi-conducting crystal contact element is mainly, silicon, the production of said silicon contact element by a process which includes the step of introducing into silicon that is substantially freed from the metallic impurities common in commercial silicon a determinate quantity of at least one of the two metals chromium and molybdenum, the quantity of such additive being at least of the order of 10% of the silicon, and a determinate relatively small quantity of at least one of the two metals aluminium and beryllium,which form a solid solution with the silicon.
3. In the manufacture of an electrical crystal contact device of the kind in which the semiconducting crystal contact element is mainly silicon, the production of'said silicon contact element by a process which includes the step of introducing into silicon that is substantially freed from the metallic impurities common in commercial silicon a determinate quantity of at -least one of the two metals chromium and molybdenum, the quantity of such additive being at least of the order of 10% of the silicon, and a determinate quantity of at least one of the two metals aluminium and beryllium, which form a solid solution with the silicon, the quantity of such latter additive bein of the order of between /2% and 1% of the silicon. r
.4. In the manufacture of an electrical crystal contact device of the kind in which the semiconducting. crystal contact element is mainly silicon, the production of said silicon contact element by a process which includes the steps of purifying commercial silicon so as to eliminate therefrom substantially all its common metallic impurities, and thereafter melting the purified silicon in vacuo in a crucible at least the interior surfaces of the walls of which are composed of pure beryllia, with between and of its weight of at least one of the two metals chromium and molybdenum and with enough of at least one of the two metals aluminium and beryllium to give a content of substantially /2% of the latter additive in the final product;
5. In the manufacture of an electrical crystal contact device oi' the kind in which the semiconducting crystal contact element is mainly silicon, the production of said silicon contact element by a process which includes the steps of purifying commercial silicon so as to eliminate therefrom substantially all its common metallic impurities, and thereafter melting the purified silicon in vacuo in a crucible, at least the interior surfaces of the walls of which are composed of pure beryllia, with substantially 20% of chromium and with enough aluminium and beryllium to give a content of substantially 4% of each of said last two metals in the final prodnot.
6. In the manufacture of an electrical crystal contact device of the kind in which the semiconducting crystal contact element is mainly silicon, the production of said silicon contact elernent by a process which includes the steps of introducing into silicon that is substantially freed from the metallic impurities common in commercial silicon a determinate quantity of at least one of the two metals chromium and molybdenum, the quantity of such additive being at least of the order of 10% of the silicon, and a determinate quantity of at least one of the two metals aluminium and beryllium, which form a solid solution with the silicon, the quantity of such latter additive being of the order of between /2% and 1% of the silicon, polishing a plane part of the surface of a fragment of the resulting product, thereafter treating saidfragment with hydrofluoric acid, thereafter heating said fragment in an oxidising atmosphere, thereafter treating said fragment with hydrofluoric acid so as to remove some but not all of the oxide layer formed during said heating, and finally depositing a metallic layer on at least part of the unpolished surface of said fragment,
'7. An electrical crystal contact device including a semi-conducting crystal contact element comprised of silicon which contains a quantity, of the order of at least 10% of the silicon, of at least one of the two metals chromium and molybdenum, said element having a polished and oxidised surface, and a metallic contact element cooperating with said surface of said crystal element.
8. An electrical crystal contact device including a semi-conducting crystal contact element comprised of silicon which contains a quantity, of the order of at least 10% of the silicon, of at least one of the two metals chromium and molybdenum, together with a determinate relatively small quantity of at least one of the two metals aluminium and beryllium, said element having a polished and oxidised surface, and a metallic contact element cooperating with said surface of said crystal element.
9. An electrical crystal contact device including a semi-conducting crystal contact element comprised of silicon which is substantially free from the metallic impurities common in commercial silicon but which contains a quantity,- between substantially 10% and 20% of the weight of silicon, of at least one of the two metals chromium and molybdenum, together with a quantity, between substantially and 1% cf the weight of silicon, of at least one of the two metals aluminium and beryllium, said element having a polished and oxidised, surface, and a metallic contact element co-operating with said surface of said crystal element.
10. An electrical crystal contact device inc1uding a semi-conducting crystal contact element comprised of silicon which is substantially free from the metallic impurities common in commercial silicon but which contains substantially 20% of chromium, of aluminium and of beryllium, these percentages being of the weight of silicon, said element having a partially etched-away oxidised and polished surface, and a metallic contact element co-operating with said surface of said crystal.
11. An electrical crystal contact element comprising silicon and a quantity, of the order of at least ten per cent by weight of the silicon, of at least one of the 'tWo metals chromium and molybdenum.
12. .An electrical crystal contact element comprising silicon, a quantity of the order of at least ten per cent by weight of the silicon of at least one of the two metals chromium and molybdenum, and a determinate relatively small quantity of at least one of the two metals aluminium and beryllium.
13. An electrical crystal contact element comprising silicon, a quantity between substantially ten per cent and twenty per cent by weight of the silicon of at least one of the two metals chromium and molybdenum, and a quantity between substantially one-half per cent and one per cent by weight of the silicon of at least one of the two metals aluminium and beryllium.
14. An electrical crystal contact element comprising silicon which is substantially free from the metallic impurities common in commercial silicon, twenty per cent of chromium by weight of the silicon, and one-quarter per cent of aluminium and one-quarter per cent of beryllium by weight of the silicon.
15. An electrical crystal contact element comprising silicon and a quantity of the order of at least ten per cent by weight of the silicon of at least one of the two metals chromium and molybdenum, said element having at least one polished and oxidised surface area.
16. An electrical crystal contact device comprising silicon, between substantially ten per cent and twenty per cent by weight of the silicon of at least one of the two metals chromium and molybdenum, and between substantially one-half per cent and one per cent by weight of the silicon of at least one of the two metals aluminium and beryllium, said element having at least one polished and oxidised surface area. i
CHARLES ERIC RANSLEY.
file of this patent:
UNITED STATES PATENTS Number Name Date Feussner et al. Feb. 5, 1935
US523748A 1943-03-22 1944-02-24 Crystal contacts of which one element is silicon Expired - Lifetime US2438944A (en)

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US2560792A (en) * 1948-02-26 1951-07-17 Bell Telephone Labor Inc Electrolytic surface treatment of germanium
US2619414A (en) * 1950-05-25 1952-11-25 Bell Telephone Labor Inc Surface treatment of germanium circuit elements
US2654834A (en) * 1949-11-01 1953-10-06 Motorola Inc Transmit-receive switch
US2701326A (en) * 1949-11-30 1955-02-01 Bell Telephone Labor Inc Semiconductor translating device
US2745046A (en) * 1945-07-13 1956-05-08 Purdue Research Foundation Alloys and rectifiers made thereof

Families Citing this family (2)

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DE1032406B (en) * 1955-07-09 1958-06-19 Licentia Gmbh Method for producing alloy contacts on semiconductors
DE1041164B (en) * 1955-07-11 1958-10-16 Licentia Gmbh Process for the production of electrically asymmetrically conductive systems with a semiconductor crystal

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US1990277A (en) * 1930-09-13 1935-02-05 Feussner Otto Metals of the platinum group and certain alloys

Patent Citations (1)

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US1990277A (en) * 1930-09-13 1935-02-05 Feussner Otto Metals of the platinum group and certain alloys

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2745046A (en) * 1945-07-13 1956-05-08 Purdue Research Foundation Alloys and rectifiers made thereof
US2801376A (en) * 1945-07-13 1957-07-30 Purdue Research Foundation Alloys and rectifiers made thereof
US2560792A (en) * 1948-02-26 1951-07-17 Bell Telephone Labor Inc Electrolytic surface treatment of germanium
US2654834A (en) * 1949-11-01 1953-10-06 Motorola Inc Transmit-receive switch
US2701326A (en) * 1949-11-30 1955-02-01 Bell Telephone Labor Inc Semiconductor translating device
US2619414A (en) * 1950-05-25 1952-11-25 Bell Telephone Labor Inc Surface treatment of germanium circuit elements

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BE467418A (en)
CH265647A (en) 1949-12-15
FR927778A (en) 1947-11-10
NL64663C (en)
GB578013A (en) 1946-06-12

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