The terahertz (THz)
region, which is based on 1THz frequency, separates electronics from photonics
and has been difficult to access for ages. Semiconductor electronics
cannot handle frequencies equal to or greater than 100GHz due to various
transport-time related limitations. In other hand, photonics devices fail to
work below 10THz as photon’s energy significantly drops to thermal energy. Terahertz
Electronics (TE) is a new technology that extends
the range of electronics into the THz-frequency region.
The main goal of Terahertz Electronics is to build a bridge
between low-frequency “Electronics” and high-frequency “Photonics”. Since
these devices use photon-electron particle interactions, as photon energy “hv”
decreases below thermal energy “kT”, the device ceases to operate efficiently
unless it is cooled down. At the low-frequency end, electronics cannot operate
above 100GHz as transport time is dependent on drift and diffusion speeds of
electrons/holes. As a result, a large region between 100GHz and 10THz remained
inaccessible. Terahertz Electronics solves this problem efficiently by cleverly
incorporating electronics with photonics.
Terahertz electronics
technology offers practical applications in high-speed data transfer, THz imaging,
and highly-integrated radar and communication systems. Surprisingly
enough, It does not use semiconductors. Instead, it is based on
metal-insulator tunneling structures to form diodes for detectors and
ultra-high-speed transistors for oscillator based transmitters.
One drawback of the
Terahertz Electronics is, it requires high-frequency radiation sources. Lack of
a small, low-cost, moderate-power THz source is one of the main reasons that
THz applications have not fully materialized yet. Scientists are trying to find
a solution to this problem. They created a compact device that can lead to
portable, battery-operated sources of THz radiation. This new solid-state
T-ray source uses high-temperature superconducting crystals that contain stacks
of Josephson junctions. So, even a small voltage, around
two millivolts per junction, can induce frequencies in the THz range.
TE devices are
extremely fast and they are made entirely of thin-film materials—metals and
insulator. Hence, it is possible to fabricate Terahertz Electronics devices on
top of complementary metal oxide semiconductor (CMOS) circuitry—a technology for
creating integrated-circuits circuitry or on an extensive variety of substrate
materials. In TE devices, charge transport through the junction occurs via
electron tunneling. Further research and development will make Terahertz
Electronics a reality in not-so-distant future.
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