In the age of CMOS, we have developed different transistor
technologies to make device smarter, faster and operate in any condition.
Research in VLSI has taken future steps for the upcoming generation.
SiliconMentor is a platform for the VLSI engineers to utilize their technical
skills for the creation and development of a device that can be operated at several parameters.
A few of the present and future transistor technologies are described below:
*BJT *JFET *MOSFET *MESFET *FinFET (Tri-gate, InGaAs)
*UTB SOI *CNT FET *SET *Vacuum channel Transistor
*Tunnel FET *SiNW FET *Plasma Transistor *Green FET
*Graphene based 2-D transistor *Spin-MOSFET *optical transistor
A few of the present and future transistor technologies are described below:
*BJT *JFET *MOSFET *MESFET *FinFET (Tri-gate, InGaAs)
*UTB SOI *CNT FET *SET *Vacuum channel Transistor
*Tunnel FET *SiNW FET *Plasma Transistor *Green FET
*Graphene based 2-D transistor *Spin-MOSFET *optical transistor
Ultra
thin Body Silicon-on-Insulator: Its name suggests that a
silicon layer or MOS develops on the insulating layer. It can eliminate the
punchthrough path between drain and source. It also removes the short-channel
effects. Many companies work at UTB-SOI
transistor technology.
FinFET:
In FinFET, the
conducting channel is enfolded by a thin silicon "fin", which forms
the body of the transistor. The thickness of the fin (measured in the direction
from source to drain) determines the effective channel length of the device.
The enfold-around gate structure provides a better electrical control over the
channel and thus helps in reducing the leakage current and overcoming other
short channel effects.
Vacuum Channel
Transistor: In this new transistor, electrons propagate freely through the nothingness of a
vacuum and it produces less noise and distortion than solid state semiconductor
materials. Vacuum-channel transistors could work 10 times as fast as ordinary
silicon transistors and may be able to operate at terahertz frequencies, which
is beyond the reach of any solid-state device.
CNT FET: CNT FET uses carbon
nanotube as the channel instead of bulk. CNT transistor switches using less power than
ordinary silicon bulk transistor. It has better compatibility with high-k
dielectric and five times higher transconductance.
Tunnel FET: A new transistor
design—the tunnel FET or TFET (we take the advantage of tunnelling of electrons
through thin barriers in MOSFET) which works by raising or lowering an energy
barrier to control the flow of current, the tunnel transistor keeps this energy
barrier high. The device switches on and off by changing the probability that
electrons on one side of that barrier will materialize on the other side. In
the tunnel FET, we use the gate to control the electrical thickness of the
barrier and thus the probability that electrons can slip through it.
In a TFET, we use p-i-n and n-i-p
configurations for transistor. The intrinsic state (electron as
well as holes) corresponds to the maximum resistivity that a semiconductor can
have. TFETs should be able to switch with a much smaller voltage swing than
that required in a MOSFET. Tunnel junctions like the one used in the TFET are
also widely used to connect multijunction solar cells and to trigger
semiconductor-based quantum cascade lasers.
Single electron transistor: Two electrodes (drain and source) connected through tunnel junctions to one common
electrode with a low self-capacitance, known as the island
(or Quantum Dot). The electrical potential of the island can be tuned by
a third electrode (known as the gate) which is capacitively coupled
to the island.
Transistor that
runs on Protons: Scientists have developed a first
solid-state transistor that controls the flow of protons instead of electrons.
The device could help to interface at a molecular level with living systems,
since biology commonly involves protons and ions to perform work and transmit
information. There are no p-n junctions
to block current when the device is off. So the device functions more like a
wire with variable conductivity than as a perfect switch.
In this transistor, palladium was
the key to getting the transistor to work, because it is one of a rare group of
materials that can absorb hydrogen, creating a hydride that can easily accept
and donate protons. Using this material to build the source and the drain
allowed the team to inject protons into the channel just as in an electronic
transistor.
Plasma transistor: The new
micro-plasma transistors work at temperatures of up to 790 °C (inside nuclear reactors). They could be used to make electronics for
controlling robots that conduct tasks inside a nuclear reactor. The channel in
a plasma transistor consists of a partially ionized gas, or plasma, instead of a semiconductor
bulk. An electron emitter (typically silicon) injects electrons into the plasma
when a voltage is applied to it. Plasmas are generated at high temperatures,
making them suitable for a risky-environment transistor. In addition to working
in nuclear reactors, the new high degree-temperature transistors could be used
to generate X-rays.
Optical transistor:
An optical transistor is a device that amplifies or switches
optical signals. Light fall on an optical transistor’s input changes the intensity of light emitted
from the transistor’s output. Since the input
signal intensity may be weaker than that of the source, this transistor
amplifies the optical signal. Optical transistors provide a means to control
light using only light and has applications in optical computing and fiber-optic
communication networks.
Grephene based
Transistor:
Graphene is a 2-D one atom thick
layer of graphite. It is light, strong, nearly transparent and excellent
conductor of heat and electricity.
A transparent thin-film transistor
(TFT) has developed from tungsten diselenide (WSe2)/
molybdenum disulfide
(MoS2) as the
semiconducting layer, graphene for the electrodes and hexagonal boron nitride
as the insulator.
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| Future Transistor technology : VLSI |
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