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Quantum dots are light emitters that are used in diode lasers, amplifiers, and biological sensors and show great promise as a potential qubit in solid-state quantum computation. Another cutting edge application of quantum dots is as potential artificial fluorophores for intra-operative detection of tumours using fluorescence spectroscopy. Quantum dots are semiconductor nanostructures that range from colloidal semiconductor nanocrystals with a size from 2 to 10 nm, to self-assembled quantum dots that are typically between 10 and 50 nm in size. A quantum dot has a discrete energy spectrum with the energy levels determined by the physical size of the dot. Consequently when the dot fluoresces or spontaneously emits light, the wavelengths radiated are determined by the dimensions of the dot and not the band gap energy of the semiconductor material.
As a result dots with different diameters emit light at different wavelengths as shown in figure 1 ( Figure 1: The fluorescence observed from quantum dots with different diameters that are made from the same material Cadium Selenide (CdSe) ). The aim of this project is to create novel minature light sources by growing the QDs in films and chains and placing them in structures that will be fabricated here at QUT with the Focussed Ion Beam facility. The nonlinear and linear optical properties of these materials will be enhanced by the structure allowing for appreciable levels of light to be produced.