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September 11th, 2011

Novel Developments for Semiconductor Quantum Dots

Abstract:
Semiconductor quantum dots (QDs) are nanoparticles or nanorods made of a semiconductor material. Because of their unique properties, they can be used in many fields, such as medicine and electronics. Here, we give a description of how QDs work and of some of their most novel applications.
Semiconductors

A material behaves as a semiconductor when its electrical conductivity is in between that of an insulator and that of a conductor.

The mechanism of the conductivity in a semiconductor is shown in the Figure below. Electrons, normally in the valence band, have to be promoted into the conduction band; for this to happen, an appropriate amount of energy has to be absorbed by the material. This value, called the band gap, is different depending on the material.
Nano-dimensions

The peculiarity of QDs is that they combine their semiconductor properties with

Valance and conduction bands in a semiconductor. Photo by mitopensourseware

those of a nanomaterial.

A nanomaterial is a material having at least one dimension in the order of nanometers (10-9 m), this usually meaning smaller than about 100 nm. Examples are nanoparticles (particles with a nanoscale diameter), nanorods (rods with all dimensions in the nanoscale) or nanofibres (fibers with a nanoscale diameter), and nanofilms (thin films with a nanoscale thickness). Due to their small dimensions, the properties of nanomaterials are normally different from those of the corresponding bulk material.

Source:
decodedscience.com

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