Krishan S Tarneja

39335275, Jan 20, 1976

Mar 9, 1973

5/339699

Krishan S. Tarneja - Pittsburgh PA
John Bartko - Pittsburgh PA
Joseph E. Johnson - Pittsburgh PA

Westinghouse Electric Corporation - Pittsburgh PA

H01L 21263

148 15

Diodes of a particular type are fine tuned with irradiation to optimize the reverse recovery time while minimizing forward voltage drop and providing more uniform electrical characteristics. The initial and desired minority carrier lifetimes in the anode region of the type are determined as a function of forward voltage drop and reverse recovery time, and the minority carrier radiation damage factor is determined for a desired type of diode and radiation source. The radiation dosage to achieve the desired carrier lifetime with the radiation source is thereafter determined from the function 1/. tau. = 1/. tau. sub. o + K. phi. , where. tau. is the desired minority carrier lifetime,. tau. sub. o is the initial minority carrier lifetime, K is the determined minority carrier radiation damage factor and. phi. is the radiation dosage.

42408440, Dec 23, 1980

Dec 22, 1978

5/972302

Patrick E. Felice - Hempfield Township, Westmoreland County PA
John Bartko - Monroeville PA
Krishan S. Tarneja - Pittsburgh PA
Chang K. Chu - Pittsburgh PA

Westinghouse Electric Corp. - Pittsburgh PA

H01L 21263
H01L 2126

148 15

The switching time of certain semiconductor devices is decreased while maintaining other electrical characteristics of the devices by irradiating them with a neutron radiation source of greater than 1. 0 Mev. to a dosage between 1. times. 10. sup. 11 and 1. times. 10. sup. 15 neutrons per square centimeter. The irradiation is preferably to a dosage between 1. times. 10. sup. 1 and 1. times. 10. sup. 14 neutrons per square centimeter and preferably has substantial energy greater than 14 Mev. The devices are also annealed during and/or subsequent to the irradiation at a temperature higher than the highest specified temperature and preferably at least 50. degree. C. higher than the highest specified temperature.

40750370, Feb 21, 1978

May 17, 1976

5/687278

Krishan S. Tarneja - Pittsburgh PA
Joseph E. Johnson - Pittsburgh PA
John Bartko - Pittsburgh PA

Westinghouse Electric Corporation - Pittsburgh PA

H01L 21263

148 15

The recovery charge of power diodes and thyristors is tailored and matched by irradiation through a major surface of the semiconductor body with a given radiation source, preferably of electron radiation, to a dosage corresponding to between about 1. times. 10. sup. 12 and 8. times. 10. sup. 12 electrons per centimeter square with 2 MeV electron radiation. Preferably, the recovery charge of each device of a group of a type of diode or thyristor is first measured, and the group divided into subgroups according to the measured recovery charge of each device. The devices of at least one subgroup is then irradiated with said given radiation source to dosages corresponding to between about 1. times. 10. sup. 12 and 8. times. 10. sup. 12 electrons per centimeter square with 2 MeV electron radiation, and the recovery charge of each irradiated device is again measured to determine the incremental change of recovery charge as a function of irradiation dosage.

43115349, Jan 19, 1982

Jun 27, 1980

6/163548

John Bartko - Monroeville PA
Krishan S. Tarneja - Pittsburgh PA
Chang K. Chu - Pittsburgh PA
Earl S. Schlegel - Plum Borough PA

Westinghouse Electric Corp. - Pittsburgh PA

H01L 21263
H01L 29167
H01L 754

148 15

A method of reducing the reverse recovery charge of thyristors without substantially increasing forward voltage drop by first determining the depth of the anode PN junction from a major surface adjoining a cathode emitter region. The depth of maximum defect generation in thyristor on irradiation through the major surface with a given radiation source radiating particles with molecular weight greater than one, preferably proton or alpha particles, and adjusting the energy level at the major surface of the thyristor from the radiation source to provide the depth of maximum defect generation adjacent the anode PN junction and preferably in the anode base region within 20 micrometers of the anode PN junction or in the anode emitter region within 15 micrometers of the anode PN junction. Thereafter the thyristor is irradiated through said major surface with the adjusted energy level from the radiation source to a given dosage to reduce the reverse recovery stored charge of the thyristor without substantially increasing the forward voltage drop.