Masters Theses

Lo-Soun Su

Abstract

"When operating a silicon planar epitaxial transistor in the inverse configuration (i.e., with the emitter functioning as a collector and the collector functioning an emitter) the bulk space-charge volume of the new "emitter-base" junction is increased by a factor of 26.5 times that of the normal emitter-base junction. The carrier concentration in the new "emitter" is decreased by five orders of magnitude from that of the normal emitter, thus making it easier to investigate the effects of neutron radiation on the space-charge region and at the surface. Experiments using biasing of the new "emitter-base" junction during neutron radiation to change the depletion layer width have been performed. Surface effects in the form of an inversion layer adjacent to the "emitter-base" junction have been observed. These surface effects cause the base current to increase by a factor of 5 to 10 in the low "emitter-base" voltage region and the "emitter-base" junction capacitance to increase by a factor of approximately 2 at a fluence level of 2 x 10¹⁴nvt. The "emitter-base" junction was reverse biased at 3.0V during irradiation in this experiment. These surface effects were found to significantly anneal at room temperature. A decrease in the diffusion potential of the "emitter-base" junction was predicted on theoretical grounds and experimentally observed after irradiation. The diffusion potential increased after isochronal annealing but did not return to its pre-irradiated value. For the annealing studies, pairs of devices with nearly identical characteristics (matched within 10 per cent) were used with one device of each pair used for isothermal annealing and the other device of each pair used for isochronal annealing. One pair of devices was forward biased at 0.5V, the second pair of devices was reverse biased at 3.0V, and the third pair of devices was unbiased during isothermal and isochronal annealing. Activation energies of 0.19 ł 0.4eV and 0.86 ł 0.15eV in the bulk space-charge region, 0.34 ł 0.06eV and 0.98 ł 0.18eV in the neutral base region were calculated from these isochronal and isothermal annealing data. No solid conclusions concerning the annealing rate of defects in the bulk space-charge region can be drawn because of the apparent descrepencies [sic] between the isothermal and isochronal annealing data. The unannealed fraction of defects in the neutral base region was found to increase in the temperature range from 50⁰ to 100⁰C and was attributed to an increase in the concentration of A-centers (oxygen-complexes). The annealing rates of defects both in the space-charge region and in the neutral base region were enhanced by the externally applied reverse voltage over temperature range from 150⁰C to 180⁰C, while the annealing rate of defects in the p-type neutral base region was retarded by the minority carrier injection above 50⁰C. This result agrees with previous results of Sander and Gregory"--Abstract, page i-ii.

Advisor(s)

Goben, C. A.

Committee Member(s)

Bolon, Albert E., 1939-2006
Dillman, Norman G., 1938-2010

Department(s)

Electrical and Computer Engineering

Degree Name

M.S. in Electrical Engineering

Sponsor(s)

U.S. Atomic Energy Commission

Publisher

University of Missouri--Rolla

Publication Date

1968

Pagination

v, 38 pages, 59 pages

Note about bibliography

Includes bibliographical references (pages 64-67).

Rights

© 1968 Lo-Soun Su, All rights reserved.

Document Type

Thesis - Open Access

File Type

text

Language

English

Subject Headings

Electrical engineering -- Materials -- Effect of radiation on
Semiconductors
Transistors

Thesis Number

T 2109

Print OCLC #

5995554

Electronic OCLC #

805937828

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