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This Week’s Citation Classic_________
1Trumbore F A. Solid solubilities of impurity elements in germanium and silicon.
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Bell Syst. Tech. J. 39:205-33, 1960.
[Bell Laboratories, Murray Hill, NJ)
ply proved troublesome, however, with repeated unsuccessful attempts to pull single
crystals of very heavily arsenic-doped germanium. One evening, in despair, I suggested to my colleague Ed Porbansky that
he not turn off the crystal pulling machine.
The next morning we found a gorgeous,
uniquely shaped single crystal which had
grown due to evaporation of arsenic, the solvent! Processing these crystals resulted in a
tunnel diode patent
with Ralph Logan and
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Forrest A. Trumbore
William Spitzer which nearly brought the
Bell Laboratories
wrath of the physics community down upon
Murray Hill, NJ 07974
us. A paper describing the work was in press
in a well-known physics journal when the
November 15, 1982
patent application was belatedly classified
“On joining the infant solid-state revolu- secret by a branch of the armed forces.
tion at Bell Laboratories in 1952, I was im- (Why, we never knew.) Reason prevailed,
mediately seduced by the beauty of those
fortunately, and the patent was declassified
early germanium and silicon single crystals,
just in time to prevent a proposed impoundthe forerunners of today’s bologna-size in- ing of the entire pressrun of the journal in
gots from which the ubiquitous silicon chip question!
is manufactured. The control of the distribu“Later, I extended my work on impurities
tion and doping levels of impurities was,
to gallium phosphide. Unexpectedly, this
and still is, fundamental to the fabrication side project yielded crystals with very interof these chips and other solid-state devices;
esting luminescence properties and I found
hence, the frequent citation of the impurity
myself in another collaborative effort with
solubility data compiled in this Citation
Logan, Harry White, and Michael Kowalchik
Classic. Happily, my own work involved the which led to the world’s most efficient light
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growth of crystals from solutions of the
emitting diodes (LED5). Contrary to a widesemiconductors in the impurity elements, ly disseminated newspaper account of our
thus indulging my fascination with crystals.
work, the LEDs were not suitable for traffic
One growth technique required up to three
lights and we had to refuse a request to
months to grow suitable crystals. The
license our LEDs for lighthouse beacons! In
growth and the subsequent chemical and
1970, in recognition of the work on imelectrical analyses of these hard-won crys- purities in the various semiconductors, I
tals to yield the solubility data involved the received the first Electronics Division Award
cooperation of many highly competent col- of the Electrochemical Society. The Citation
leagues in a truly golden era at Bell
Classic was also reprinted in a book in
Laboratories.
1964.~
“Fortunately, my efforts were directed
“This commentary would be incomplete
primarily toward the more soluble impuri- without acknowledging Carl Thurmond,
ties (e.g., gallium and arsenic). When Esaki,’
who inspired this paper. His tireless and
in Japan, invented the tunnel diode, a de- stimulating efforts in educating, consulting,
vice requiring heavily doped semiconduc- and arguing with his colleagues on materials
tors, I became an instant authority on tunnel problems represented a truly significant
diode materials by simply supplying my contribution to the solid-state revolution
device-oriented colleagues with crystals which has not been adequately recognized
from my desk drawer. Replenishing the sup- outside of Bell Laboratories.”
Solid solubility data are reported for various
impurity elements in germanium and silicon.
These results and other available data are
summarized and critically evaluated to yield
sets of solidus and solvus curves for the major dopants in these semiconductor host materials. [The SC!® indicates that this paper
has been cited in over 350 publications since
1961.1
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1. Eaakl L New phenomenon in nanow germanium p-n junctions. Phys. Rev. 109:603-4, 1958.
2. Log,. k A, Spltzer W G & Tr.hore F A. Method for increasing the doping level of,cemiconduc:or material,s.
US patent 3.111,433. 19 November 1963.
3. Logan Il A, White H 6 & Ti,bore F A. P-N junctions in GaP with external electroluminescence efficiency “2%
at 25°C.AppI. Phys. Let:. 10:206-8. 1967.
4. Tt.abore F A. Solid solubilities of impurfly elements ingermanium and silicon. (Levine S N, ed.)
Micro- and thin-film electronics: readings. New York: Holt, Rinehart and Winston, 1964.
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