Quantum Dots : A Brief Overview

Extract

[...] This is an example of how the tuneable optical properties of quantum dots are used for practical applications. A monolayer of CdSe dots, sandwiched between the Hole Transport Layer and Electron Transport Layer acts as the Emissive Layer. The recombination of holes and electrons gives rise to radiation. The advantage of such a thin recombination layer is that a greater percentage of holes and electrons recombine resulting in much higher efficiency Fig Conclusion Quantum Dots are an emerging area of research and have the scope for many novel applications. We have [...]

[...] This can be summarized using the Heisenberg uncertainty relation as : Fig Fig Fig ΔEΔT=(e2/C)(RC)>h Or R>h/e2 In Fig 8 we see a schematic with μ(left/right) being the chemical potential of the drain/source. The solid lines indicate occupied energy levels and the dashed lines indicate unoccupied ones. As the gate voltage Vg is changed an unoccupied level lines up with μ(left/right) leading to charge degeneracy. As a result there is current flow through the dot. However despite a finite drain source voltage Vsd=(μleft - μright)/e, if the chemical potentials are not aligned there can be no flow of electrons. [...]

[...] Using this process one can fabricate much smaller dots (of the order of a few and can achieve much stronger confinement potentials. However ordered growth of these dots is still a challenge. Electronic Properties : Coulomb Blockade Single Electron Tunnelling Probably the most remarkable, and useful property of the quantum dot is that single electrons can move into and out of the dot. From the point of view of electronics, it is extremely desirable to be able to control this process. [...]