Professor Herbert Kroemer

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Professor Herbert Kroemer


ECE Department and Materials Department

Room 2205A, Engineering Science Building

University of California

Santa Barbara, CA 93106
-
9560

(805) 893
-
3078 (Voice) and
-
7990 (Fax)

kroemer@ece.ucsb.edu


Professor Kroemer received a Ph.D
. in Theoretical Physics in 1952 from the University of
Göttingen, Germany, with a dissertation on hot
-
electron effects in the then
-
new transistor,
setting the stage for a career in research on the physics and technology of semiconductors
and semiconductor

devices. Following work in several research laboratories in Germany
and the USA, Kroemer persuaded the ECE Department at UCSB in 1976 to put the
limited resources it had available for expanding their small semiconductor research
program,
not

into mainstre
am silicon technology, but into the emerging compound
semiconductor technology. In this field, Kroemer saw an opportunity for UCSB to
become one of the leading institutions. He himself became the first member of the group,
thus founding what has grown into

a large group that is second to none in the physics and
technology of compound semiconductors and devices based on them.


In his research. Prof. Kroemer has always preferred to work on problems that are one or
two generation ahead of established mainstrea
m technology. In the mid
-
‘50s, he was the
first to point out that great performance advantages could be gained in various
semiconductor devices by incorporating what is now called
heterostructures

into the
devices [1]. Most notably, in 1963 he proposed the

concept of the double
-
heterostructure
laser, the central concept in the field of semiconductor lasers, without which that field
would simply not exist [2, 3]. These ideas were far ahead of their time, and required the
development of modern epitaxial growt
h technology before they could become
mainstream technologies, in turn providing a great stimulus towards the development of
these technologies. Kroemer’s receiving the Physics Nobel Prize in 2000 can ultimately
be traced to these early papers. Only by 198
0 had the technology progressed to the point
that the 80’s became a decade of “Heterostructures for Everything [5]”


a topic that
continues to dominate compound semiconductors

not just lasers and light
-
emitting
diodes, but integrated circuits as well [6]

a
nd is even invading mainstream silicon
integrated circuit technology.


Parallel to his work on heterostructures, Kroemer pursued the problem of high
-
field
electron transport, especially negative
-
resistance effects such as the Gunn effect [4], and
the cruc
ial enabling role of non
-
trivial energy band structure in such effects.


Upon coming to UCSB, Kroemer turned to experimental work and became one of the
early pioneers in molecular beam epitaxy, concentrating from the outset on applying the
technology to un
tried new materials systems, such as GaP and GaAs on silicon. In 1985,
his work shifted towards the “6.1Å group” of materials, InAs, GaSb, and AlSb, a group
where he saw great opportunities for basic research as well as for future devices. One
intensively
studied research area involved superconductor
-
semiconductor hybrid
structures where InAs
-
AlSb quantum wells are contacted by superconducting niobium
electrodes, which induce superconductivity in the semiconductor [7,8]. Another area
involved electron trans
port in semiconductor superlattices under sufficiently strong
electric fields that the electrons undergo oscillations within the tilted energy bands. Such
structures might be capable of serving as oscillators

commonly called
Bloch
oscillators

up to frequen
cies in the terahertz regime [9].


Since the late 1990s, Kroemer has reverted to purely theoretical work, some of which
continues earlier work [8,9,12], some is in newer research areas, like electromagnetic
wave propagation in photonic crystals, especiall
y negative
-
refraction effects, as well as
the physics of nanostructures.


Prof. Kroemer’s research has been widely recognized by the semiconductor and physics
community, and he has been honored with numerous awards, including several national
and internati
onal ones:




J.J. Ebers Award of the Electron Devices Group of the IEEE (1973)



Heinrich Welker Medal of the International Symposium on GaAs and Related
Compounds (1982)



National Lecturer, IEEE Electron Devices Society (1983)



UCSB Faculty Research L
ecturer (1985)



Honorary Doctorate in Engineering, Technical University of Aachen, Germany
(1985)



Jack Morton Award of IEEE (1986)



Donald W. Whittier Chair in Electrical Engineering (1986)



Alexander von Humboldt Research Award (1994)



Election to N
ational Academy of Engineering (1997)



Honorary Doctorate in Technology, University of Lund, Sweden (1998)



Nobel Prize in Physics (2000)



Fellow, Institute of Pysics (2000)



Golden Plate Award, American Academy of Achievement (2001)



Order of Merit o
f the Federal Republic of Germany (2001)



Honorary Doctorate in Science, University of Colorado (2001)



Goff Smith Prize, University of Michigan (2002)



IEEE Medal of Honor (2002)



Election to National Academy of Sciences (2004)


Selected Early Publica
tions:



[1]

H. Kroemer, “Quasi
-
Electric and Quasi
-
Magnetic Fields in Non
-
Uniform
Semiconductors,”
RCA Review
, vol.
18
, pp. 332
-
342, 1957.


, “Theory of a Wide
-
Gap Emitter for Transistors,”
Proc. IRE,

vol.
45
, pp. 1535
-
1537, 1957.



[2]

H. Kroemer, “A Prop
osed Class of Heterojunction Injection Lasers,”
Proc. IEEE
,
vol.
51
, pp. 1782
-
1783, 1963.



[3]

H. Kroemer, “Solid State Radiation Emitters,” U.S. Patent 3,309,553, March 14,
1967. (Filed Aug. 16, 1963).



[4]

H. Kroemer, “Theory of the Gunn Effect,”
Proc.

IEEE
, vol.
52
, p. 1736, 1964.



[5]

H. Kroemer, “Heterostructures for Everything: Device Principle of the 1980’s?,”
Jpn. J. Appl. Phys.
, vol.
20

(Supplement 20
-
1), pp. 9
-
13, 1981.



[6]

H. Kroemer, “Heterostructure Bipolar Transistors and Integrated Circ
uits,”
Proc.
IEEE
, vol.
70
, pp. 13
-
25, 1982.


Selected Recent Publications



[7]

M. Thomas, H.
-
R. Blank, K. C. Wong, H. Kroemer, and E. Hu, “Current
-
voltage
characteristics of semiconductor
-
coupled superconducting weak links with large
electrode separation
s,”
Phys. Rev. B
, vol.
58
, pp. 11676
-
11684, 1998.



[8]

H. Kroemer, “Quasiparticle dynamics in ballistic weak links under weak voltage
bias: an elementary treatment,”
Superlattices and Microstructures
, vol.
25
: pp,
877
-
889, 1999.



[9]

H. Kroemer, “Large
-
amplitude oscillation dynamics and domain suppression in a
superlattice Bloch oscillator,”
cond
-
mat
/0009311, Sept. 2000.



[10]

H. Kroemer, “Nobel Lecture: Quasi
-
electric fields and band offsets: Teaching
electrons new tricks,”
Reviews of Modern Physics
,
vol.
73
, pp. 783
-
793, 2001.



[11]

H. Kroemer, “Speculations about Future Directions,”
J. Crystal Growth
, vol.
207
,
pp. 17
-
22, 2003.



[12]

H. Kroemer, “Wave Packet Dynamics in a Biased Finite
-
Length Superlattice,”
cond
-
mat
/0310019, Oct. 2003



[13]

H. Kro
emer, “The Thomas precession factor in spin
-
orbit interaction,”

Am. .f Physics
, vol.
72
, pp. 51
-
52 2004.



[14]

H. Kroemer, “The 6.1 Angstrom family (InAs, GaSb, AlSb) and its
heterostructures: a selective review,”
Physica E
, vol.
20
, pp. 196
-
203, 2004.



[15]

H. Kroemer, “Nano
-
whatever: Do we really know where we are heading?”
Physica
Status Solidi (a),

vol.
202
, pp. 957
-
964, 2005.