05-05-2014, 11:06 AM
Seminar On QUANTUM DOTS
QUANTUM DOTS.pptx (Size: 246.74 KB / Downloads: 18)
What Is A Quantum Dot?
A quantum dot is a semiconductor whose excitons are confined in all three spatial dimensions
In other words Quantum Dots are zero-dimension semiconducting structures.
Quantum dots (QDs) are also known as artificial atoms.
Quantum dots can be observe in transistors, LEDs, diode lasers etc.,
First discovery of QDOT was in ‘glass matrix’ then in colloidal solutions
Dots are made of binary alloys such as CaSe, cadmium sulfide, InAs, and indium phosphide
Dots are grown by advanced epitaxial techniques in nanocrystals produced by chemical methods or by ion implantation, or in nanodevices made by state-of-the-art lithographic techniques.
Why Quantum Dots?
They radiate light at wavelengths determined by the energy levels of the dots, rather than the band gap energy.
Energy levels of the dots depends on the size of the individual dot or crystal.
High level of control possible over the size of the crystals produced
Precise control over the conductive properties of the material.
General and Optical Properties
Qdots have electronic properties intermediate between those of bulk semiconductors and those of discrete molecules.
Electronic characteristics of quantum dots are closely related to the size and shape of the individual crystal.
An immediate optical feature of colloidal quantum dots is their coloration
Applications
The ability to tune the size of quantum dots is advantageous for many applications
Quantum dots are used mainly in:
Quantum Computations
Photovoltaic devices
Biological applications
QDOT-Lasers
QD-LEDs etc.,