IEEE Power Electronics Magazine - June 2015 - 15

the MOS-controlled bipolar power
transistor, had several acronyms. It
was referred to as IGR in [12], COMFET in [13], insulated-gate transistor
in [22], and bipolar-mode MOSFET
(BIFET) in [23]. Today, this key
device concept is the best known as
the IGBT, which clearly describes the
true mode of device operation.
However, the question that remains
unanswered is who should be credited
with the invention of the IGBT-perhaps the most important semiconductor device concept conceived and commercialized since the silicon transistor.
There have been patent infringement
lawsuits, such as that between Stanford University and Harris Corporation
and the former RCA Corporation [24].
The true answer may be best left to the
decision of informed readers.

About the Author
Krishna Shenai (kshenai@yahoo.
com) earned his B.Tech. degree in
electronics from the Indian Institute of

Technology, Madras, India, in 1979 and
his M.S. and Ph.D. degrees in electrical
engineering from the University of
Maryland, College Park, in 1981 and
Stanford University, California, in 1986,
respectively. He is the vice president of
LoPel Corporation in Naperville, Illinois. He has made seminal contributions to power semiconductor materials and devices for over 30 years. His
research has set industry standards for
nearly three decades, and products developed based on his research have
been generating multibillion-dollar annual sales revenues. In the 1980s,
based on the pioneering optimization
of silicon power devices, he proposed
the use of WBG semiconductors for
electrical power switching. He is a Fellow of the IEEE, the American Physical Society, the American Association
for the Advancement of Science, and
the Institution of Electronics and Telecommunication Engineers (India) and
a member of the Serbian Academy of
Engineers. He has authored or coau-

thored more than 400 peer-reviewed
archival papers, ten book chapters,
and three books. He is a named inventor in 13 issued U.S. patents.

References
[1] B. J. Baliga, Modern Power Devices. New
York: Wiley, 1987.
[2] M. Yamaguchi, Japanese patent, Feb. 5, 1968.
[3] F. E. Gentry, "Four layer semiconductor
switch with the third layer defining a continuous,
uninterrupted internal junction," U.S. Patent 3
324 359, June 6, 1967.
[4] J. D. Plummer, "Monolithic semiconductor
switching devices," U.S. Patent 4 199 774, Apr.
22, 1980.
[5] B. W. Scharf and J. D. Plummer, "A MOScontrolled triac device," in IEEE Int. Solid-State
Circuits Conf. Dig. Tech. Papers., Feb. 17, 1978,
pp. 222-223.
[6] J. D. Plummer, "Monolithic semiconductor
switching devices," U.S. Patent Re33 209, 1995.
[7] J. D. Plummer and B. W. Scharf, "Insulatedgate planar thyristors: I-Structure and basic
operation," IEEE Trans. Electron Devices, vol.
ED-27, no. 2, pp. 380-387, Feb. 1980.

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June 2015

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