Classifications

• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
  • H10D48/00—Individual devices not covered by groups H10D1/00 - H10D44/00
  • H10D48/01—Manufacture or treatment
  • H10D48/04—Manufacture or treatment of devices having bodies comprising selenium or tellurium in uncombined form
  • H10D48/048—Treatment of the complete device, e.g. by electroforming to form a barrier

Definitions

• This invention relates to alternating electric current rectifiers of the selenium type comprising a base plate or support provided with a layer o coating of selenium which may or may not contain other substances or compounds of selenium, a counterelectrode being applied to the surface of the selenium layer;
• a counterelectrode composed preferably of tin, cadmium or alloys of these metals is applied for instance by a spraying or sputtering operation to the surface of the selenium, and a voltage which is high relative to the normal voltage at which the rectifier operates is applied to the rectifier in the reverse di rection with the result that the reverse resistance of the rectifier is very considerably increased without the. necessity for any chemical treatment.
• thisaction is due to local heating at the-boundary surface between the base plate and the selenium layer or at the boundary surface between the selenium layer and the counterelectrode or at both these surfaces.
• the high temperature required for the forming operation is thus attained without the duration of this temperature being sufficient to cause appreciable oxidation of the counterelectrode.
• a selenium rectifier produced by applying a layer or coating of selenium to a base plate or support and annealed by heat treatment to convert the selenium into the metallic conducting state is, Without any previous chemical treatment,
• the applied reverse voltage is now increasedto approximately 15 volts whereupon the current traversing the rectifier is increased to approximately 200 m. a. per sq. cm. and the rectifier temperature rises to over 100 C.
• the applied reverse voltage is now reduced to zero and the rectifier is allowed to cool to approximately room temperature, whereupon the applied voltage is again increased until the current traversing the rectifier is approximately 200 m. a. and a reverse voltage of approximately 20 volts will be found necessary for this purpose, and the temperature of the rectifier will again rise to over 100 C. a
• the resistance of the rectifier in the forward direction is found to be somewhat increased after the forming process but the final ratio of the reverse and forward resistance is such as to give commercially satisfactory rectification.
• the temperature of the rectifier is found to rise to over 100 C. after the application of the reverse voltage, it is probable that at one or both of the boundary surfaces above referred to between the selenium. and the base plate and counterelectrode, localised heating occurs which causes the selenium to melt at the boundary surface and thereby be transformed into an amorphous or vitreous state.
• a thin film of selenium in this condition may thus be formed at one or both of the boundary surfaces constituting a barrier layer which co-operates with the base plate or counterelectrode to effect the observed high degree of rectification eventually obtained.
• the counterelectrode employed preferably consists of the metals or alloys above specified and the all ys of these metals having a relatively high melting point are preferable in order to avoid their oxidation under the temperatures attained as far as possible.
• Counterelectrodes composed of certain other metals or alloys may however be employed and it is obviously preferable to utilise metals or alloys which do not melt or oxidise at a relatively low temperature.
• a voltage which is high relative to the normal voltage at which the rectifier operates is applied to the' rectifier in the reverse direction in successive stages or cycles each comprising a relatively short period of voltage application followed by a period in which the rectifier is cooled.
• a process for the manufacture of alternating electric current rectifiers of the selenium type in which, after the selenium coating or layer has been subjected to a heat treatment and a counterelectrode applied thereto, an electromotive force of approximately volts is first applied to the rectifier in the reverse direction to heat it to a temperature of over 100 C., the applied electromotive force is then removed and the rectifier is allowed to cool, and an electromotive force of approximately volts is then applied to the rectifier in the reverse direction.
• a process for the manufacture of alternating electric current rectifiers of the selenium type in which. after the selenium coating or layer has been subjected to a heat treatment and a counterper sq. cm. is again caused to flow through the rectifier for a period of time sufiicient to heat the rectifier to a temperature of over C.
• a process for the manufacture of alternating electric current rectifiers of-the selenium type in which after the selenium coating or layer has been subjected to a heat treatment and acounterelectrode applied thereto, a voltage which is high relative to the normal voltage at which the rectifier operates is arranged to be applied to' the rectifier in the reverse direction in successive stages or cycles each comprising a relatively short period of voltage application followed by a period in which the rectifier is cooled, for the purpose specified.
• a process for the manufacture of alternating electric current rectifiers of the selenium type in which after the selenium coating or layer has been subjected to a heat treatment and a counterelectrode composed of tin, cadmium or an alloy of these metals applied thereto, a voltage which is high relative to the normal voltage at which the rectifier operates is applied to the rectifier in the reverse direction, for the purpose specified.

Landscapes

• Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
• Rectifiers (AREA)
• Electric Propulsion And Braking For Vehicles (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=9713416

Family Applications (1)

Country Status (4)

Cited By (13)

Families Citing this family (1)

• 0
  • NL NL96218D patent/NL96218C/xx active
• 1939
  • 1939-01-11 GB GB954/39A patent/GB523673A/en not_active Expired
  • 1939-12-13 US US309040A patent/US2279187A/en not_active Expired - Lifetime
• 1940
  • 1940-01-05 FR FR862705D patent/FR862705A/fr not_active Expired

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