2. Nano:
It is derived from a greek
word NANOS which means
DWARF .
In the metric system, nano
refers to 10-9 or
1/1,000,000,000 of one meter .
3. Nanotechnology:
Nanotechnology is the branch of science and
engineering which deals with the creation of materials,
devices, and systems through the manipulation of
individuals atoms and techniques….
It is basically a technique that enables the miniaturization
of electronics products below 100 nm….
4. These days, nanotechnology has a wide area of applications.
Some of its applications are in:
Biotechnology
Electronics
Chemistry
Computing
Medicine
Physics
and many more…..
6. Nanoelectronics:
Nanoelectronics generally refers to semiconductor devices
that have been shrunk to the nanoscale.
It can also defined as the use of NANOTECHNOLOGY on
electronics components especially on TRANSISTORS.
Present days transistors are also in the range of 45 nm, 32 nm, and
22 nm, but still they are not included in the category of
nanoelectronics because nanoelectronics often refer to transistor
devices that are so small that inter-atomic interactions and
quantum mechanical properties need to be studied
extensively….
7. Moore’s Law:
According to this law, "The number of transistors that can be
placed inexpensively on an integrated circuit doubles
approximately every two years. This trend has continued for more
than half a century and is expected to continue until at least 2015
or 2020.”
8. In 1965, Gordon Moore sketched out his prediction of the pace of
silicon technology. Decades later, Moore’s Law remains true, driven largely by
Intel’s unparalleled silicon expertise.
Moore’s Law
9. Nanoelectronics devices are of two types:
Solid-state quantum-effect nanoelectronic devices
Quantum Dots (or "artificial atoms"),
Resonant Tunneling Devices, and
Single-Electron Transistors (SETs).
Molecular electronic devices
10. Single Electron Transistor (SET):
It can be defined as a
switching device that uses
controlled electron tunneling
to amplify current or as a
device that exploits the
quantum effect of tunneling to
control and measure the
movement of single
electrons…
13. The SET is made by placing 2 tunnel junctions in series.
The 2 tunnel junction create what is known as a “Coulomb
Island” that electrons can only enter by tunneling through one
of the insulators.
This device has 3 terminals like the FETs.
The cap may seem like a third tunnel junction, but is much
thicker than the others so that no electrons could tunnel
through it.
The cap simply serves as a way of setting the electric charge
on the coulomb island.
Formation of SET:
14. Working:
In SET, the charge flows through the island in
quantized units.
For an electron to hop onto the island, its energy must
be greater than the COULOMB ENERGY.
When both the gate and bias voltages are zero,
electrons do not have enough energy to enter the island
and current does not flow.
15. Working Contd…
When the bias voltage between gate and source is increased,
Electrons pass through the junction as their energy now
reaches the Coulomb Energy.
This effect is known as the Coulomb blockade, and the
critical voltage needed to transfer an electron onto the island,
equal to e/2C, is called the Coulomb gap voltage.
16. For Function:
Capacitance of the junction must be less than 10-17 Farads.
Size must be smaller than 10 nm.
To make a significant contribution in coulomb energy,
the wavelength of the electron must be of the size of a dot.
18. Application of SET:
Supersensitive Electrometer
DC Current Standards
Temperature Standards
Detection of Infrared Radiation
Voltage State Logics
Charge State Logics
Programmable Single Electron Transistor Logic
21. Conclusion:
Single Electronic Transistor (SET) has proved their value as tool
in scientific research. Researchers may someday assemble these
transistors into molecular versions of silicon chips , but there are
still formidable hurdles to cross.
SETs could be used for memory device, but even the latest SETs
suffer from “offset charges”, which means that the gate voltage
needed to achieve maximum current varies randomly from device
to device. Such fluctuations make it impossible to build complex
circuits, but the future does look bright for these devices.
