In recent years, III-V devices, integrated circuits, and superconducting
integrated circuits have emerged as leading contenders for
high-frequency and ultrahigh- speed applications. GaAs MESFETs have been
applied in microwave systems as low-noise and high-power amplifiers
since the early 1970s, replacing silicon devices. The heterojunction
high-electron-mobility transistor (HEMT), invented in 1980, has become a
key component for satellite broadcasting receiver systems, serving as
the ultra-low-noise device at 12 GHz. Furthermore, the heterojunction
bipolar transistor (HBT) has been considered as having the highest
switching speed and cutoff frequency in the semiconductor device field.
Initially most of these devices were used for analog high-frequency
applications, but there is also a strong need to develop high-speed
III-V digital devices for computer, telecom- munication, and
instrumentation systems, to replace silicon high-speed devices, because
of the switching-speed and power-dissipation limitations of silicon. The
potential high speed and low power dissipation of digital integrated
circuits using GaAs MESFET, HEMT, HBT, and superconducting Josephson
junction devices has evoked tremendous competition in the race to
develop such technology. A technology review shows that Japanese
research institutes and companies have taken the lead in the development
of these devices, and some integrated circuits have already been applied
to supercomputers in Japan. The activities of Japanese research
institutes and companies in the III-V and superconducting device fields
have been superior for three reasons. First, bulk crystal growth,
epitaxial growth, process, and design technology were developed at the
same time.
