Juras Požela (1925–2014) was a prominent
Lithuanian physicist, organizer of science and a public man very
well-known in the Lithuanian scientific community. He was the
founder and the first and long-time director of the
Semiconductor Physics Institute, a leading academic research
institution in Lithuania. Prof. J. Požela was a President of the
Lithuanian Academy of Sciences for many years, and also the
former Member of the Parliament of Lithuania.
As a young scientist, J. Požela was a doctorant of the
distinguished Russian physicist Abram Fedorovich Ioffe. At the
Ioffe Institute in Leningrad he found the main interest of his
life: semiconductor physics. His numerous scientific articles
and monographs devoted to hot electrons, plasma and current
instabilities in semiconductors, nanostructures and high speed
transistors, and electromagnetic radiation detectors were
internationally recognized and had a great impact on those
fields of research. He has published over 400 scientific papers
and 9 books, supervised 47 doctoral theses and was honoured by
numerous prizes and awards. Juras Požela and the scientific
school founded by him accustomed the Lithuanian physics to the
standards of world-class science and laid the foundations of
high-technology culture in the country.
In relation to his 90th year anniversary, the Editorial Board of
Lithuanian Journal of Physics commemorates him by devoting this
issue of our journal to semiconductor physics, publishing the
articles written by his friends, students and collaborators.
In his last years J. Požela was asked to write a text for the
Lithuanian encyclopedia about his most important works in
semiconductor physics. Below we present a shortened version of
what he thought had been his main achievements in the field:
“My scientific work was devoted to studies of electronic
processes in semiconductors. Namely, the studies of electrical
and optical properties of semiconductors raised a huge
revolution of science and technology which essentially changed
our way of life and quality of work in the second half of 20th
century. I was happy to work among the scientists who discovered
the basic physical principles and developed modern semiconductor
electronics. It is a great luck for a scientist to evidence and
participate in so fast a progress of science.
As a young researcher, I studied electrical conductivity of
semiconductors in high electric fields. This topic was proposed
by my scientific adviser, academician A. Ioffe, a famous
physicist and organizer of science.
The study of hot electrons was the main field of my scientific
interests in 1970s. Luckily, I was among those who discovered
new phenomena caused by electron heating by electric field
(leaving the crystal cold) in semiconductors. The works
performed by me and my collaborators contributed to an important
part of semiconductor physics – hot electron physics.
Making an inventory of my research, I think that my most
significant works are related to the broadening of the working
frequency of semiconductor devices from 10 to 10 000 GHz.
1. Experimental studies and measurement techniques related to
electron heating in microwave frequency (10 GHz) electric
New phenomena caused by hot electron heating: thermo and photo
electromotive force, emission, current fluctuations, generation
and recombination of carriers, non-linear conductivity, negative
absolute resistance, non-inertial current saturation and impact
ionization in high electric fields [1–4]. Discovery of the
bigradient effect [5, 6].
2. Studies in 100 GHz frequency range. Main fields:
Avalanche ionization. The injection and drift of
electrons and holes [7, 8]. Electron and hole plasma
instabilities [9, 10]. These works stimulated the development of
impact avalanche transit time diodes.
Gunn effect. Studies of the inter-valley electron
transfer by Monte Carlo method [11, 12] (see also a review on
experimental and theoretical studies of this effect ).
Electromagnetic fields in magnetized plasma in
semiconductors. Plasma and current instabilities (see, e.
g. [2, 14]). Application of the microwave technique for
generation of helicon waves in high mobility semiconductors 
(development of helicon spectroscopy ). Magnetic field
Increase of field-effect transistor efficiency. The
methods to decrease the 2D electron scattering by interface
phonons in a quantum well (quantization of the phonon trapping
and insertion of thin phonon barriers). Development of
InGaAs/InAlAs transistors (with InAs barrier) with a high
limiting current amplification frequency . A review on
transistor physics is given in [18, 19].
3. Studies of electromagnetic wave (10 000 GHz range)
interaction with phonons and free electrons in semiconductors.
(a) Population inversion of heavy and light holes of hole
conductive germanium [20, 21] in perpendicular electric and
magnetic fields. Participation in the development of a
semiconductor laser in THz range . (b) Resonant thermally
stimulated THz radiation emission from highly doped polar
semiconductor structures [23–26].”
 V. Dienys and J.
Požela, Hot Electrons
(Mintis, Vilnius, 1971) [in
 J. Pozhela, Plasma and Current Instabilities in
(Pergamon Press, 1981),
 V. Bareikis, A. Matulionis, J. Požela, S. Ašmontas, A.
Reklaitis, A. Galdikas, R. Miliušytė, and E. Starikovas, Hot
(Mokslas, Vilnius, 1981) [in Russian]
 V. Bareikis, R. Katilius, J. Pozhela, S.V. Gantsevich, and
V.L. Gurevich, Fluctuation spectroscopy of hot electrons in
semiconductors, in: Spectroscopy of Nonequilibrium Electrons
, eds. C.V. Shank and B.P. Zakcharchenya
(North-Holland, Amsterdam–London, 1992) pp. 327–396,
 S. Ašmontas, J. Požela, and K. Repšas, Bigradient
electromotive force, stimulated by hot carriers, Lit. Fiz.
Sbornik – Lietuvos fizikos rinkinys 11
(1971) [in Russian]
 Diploma No. 185. Publication about the discovery registered
in the State Register of Discoveries in USSR, in: Otkrytiya,
Izobreteniya, Promyshlennye Obraztsy, Tovarnye Znaki
Official Bulletin of the Commitee on Inventions and Discoveries
at the USSR Council of Ministers, No. 39 (Institute of Patent
Information, Moscow, 1977) p. 3 [in Russian]
 Iu.K. Pozhela, Drift of current carriers which have been
formed by the effect of a strong electric field, Sov. Phys. –
Tech. Phys. 1
, 277 (1956); Zh. Tekh. Fiz. 26
 J. Požela and A. Saulis, Injection and drift of high
concentration current carriers in germanium, Lietuvos TSR MA
darbai, Serija B 2
(22), 83–92 (1960) [in Russian]
 J. Požela, Monte Carlo simulation of charge-carrier behavior
in electric fields, Comp. Phys. Commun. 67
 J. Požela, Plasma in semiconductors and instabilities in a
short-wave part of microwaves, Lit. Fiz. Sbornik – Lietuvos
fizikos rinkinys 21
(4), 3–21 (1981) [in Russian]; J.
Požela, Transit-time instability in diode with oscillating
cathode, Fiz. Tekh. Poluprovodn. 15
(9), 1861–1862 (1981)
 A. Matulionis, J. Požela, and A. Reklaitis, Monte Carlo
calculations of hot-electron transient behaviour in CdTe and
GaAs, Phys. Status Solidi A 35
(1), 43–48 (1976),
 J. Požela and A. Reklaitis, Electron transport properties
in GaAS at high electric fields, Solid State Electron. 23
 M. Levinshtein, J. Požela, and M. Shur, Gunn Effect
(Sovetskoe Radio, Moscow, 1975) [in Russian]
 R.S. Brazis, J.K. Furdyna, and J.K. Požela, Microwave
effects in narrow-gap semiconductors (I), Phys. Status Solidi A
(1), 11–41 (1979); R.S. Brazis, J.K. Furdyna, and J.K.
Požela, Microwave effects in narrow-gap semiconductors (II),
Phys. Status Solidi A 54
(1), 11–27 (1979),
 A. Laurinavičius and J. Požela, Investigation of microwave
dispersion in n
-InSb by magnetoreflection, Phys. Status
Solidi A 21
(2), 733–740 (1974),
 A. Laurinavicius, P. Malakauskas, and J. Pozela,
Semiconductor nondestructive testing by helicon waves, Int. J.
Infrared Millimet. Waves 8
(5), 573–582 (1987),
 J. Požela, K. Požela, V. Jucienė, and A. Shkolnik, Hot
electron transport in heterostructures, Semicond. Sci. Technol.
, 014025 (2011); A. Šilėnas, Yu. Požela, K. Požela, V.
Jucienė, I.S. Vasil’evskii, G.B. Galiev, S.S. Pushkarev, and
E.A. Klimov, Maximum drift velocity of electrons in selectively
doped InAlAs/InGaAs/InAlAs heterostructures with InAs inserts,
, 372–375 (2013),
 J. Požela, Physics of High-Speed Transistors
(Plenum Press, New York and London, 1993),
 Yu.K. Pozhela, Transport parameters from microwave
conductivity and noise measurements, in: Hot Electron
Transport in Semiconductors
, ed. L. Reggiani
(Springer-Verlag, Berlin, 1985),
 Yu.K. Pozhela, E.V. Starikov, and P.N. Shiktorov,
Population inversion due to separate shift and heating of light
and heavy holes in semiconductors, Phys. Lett. 96A
 J.K. Požela, E.V. Starikov, P.N. Shiktorov, L.E. Vorobjev,
F.I. Osokin, V.I. Stafeev, and V.N. Tulupenko, The experimental
and theoretical investigation of the hot hole population
inversion and far IR radiation generation in p-Ge under EB
fields, Physica B 117–118
, 226–228 (1983),
 A.A. Andronov, L.S. Mazov, Yu.A. Mitiagin, A.V. Murav’ev,
V.N. Murzin, I.M. Nefedov, Yu.N. Nozdrin, S.A. Pavlov, J.K.
Požela, E.V. Starikov, S.A. Stoklickii, I.E. Trofimov, A.P.
Chebotarev, V.N. Shastin, and P.N. Shiktorov, Submillimeter
Lasers on Hot Holes in Semiconductors
Applied Science of AS of USSR, Gorkii, 1986) [in Russian]
 J. Požela, K. Požela, A. Šilėnas, E. Širmulis, and V.
Jucienė, Interaction of terahertz radiation with surface and
interface plasmon–phonons in AlGaAs/GaAs and GaN/Al2
heterostructures, Appl. Phys. A 110
, 153–156 (2013),
 E. Širmulis, A. Šilėnas, K. Požela, J. Požela, and V.
Jucienė, Thermally stimulated terahertz radiation of
plasmon–phonon polaritons in GaAs, Appl. Phys. A 115
 J. Požela, K. Požela, A. Šilėnas, E. Širmulis, I.
Kašalynas, V. Jucienė, and R. Venckevičius, Thermally stimulated
3–15 THz emission at plasmon–phonon frequencies in polar
semiconductors, Semiconductors 48
, 1557–1561 (2014),
 K. Požela, E. Širmulis, I. Kašalynas, A. Šilėnas, J.
Požela, and V. Jucienė, Selective thermal terahertz emission
from GaAs and AlGaAs, Appl. Phys. Lett. 105