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Unformatted text preview: Quantum Dots – Application in Life Sciences (Sridhar Busani) 004312127 2 Introduction Edison made a giant leap when he lit up the wire filament in that first incandescent light bulb. He was the hero of his days, but he was working in dark ages when compared to nano technology of these days. World has just become brighter with the invention of quantum dots. Quantum dots are nano technology crystals that emit light. The wave length with which they emit light depends on the size of the crystals. Quantum dots are made of various materials, such as lead sulfide, cadmium silinate etc. Quantum dots are important because of their power to emit a particular wave length and color depending on their composition and size. The main aim of this work is to find application of the quantum dots work to detect biological entities such as unicell organism (bacterial, micro organisms), single cell genes. In this paper we are going to see some Biological, Life Science application of quantum dots. How are quantum dots made? First we discuss how Quantum dots are made. This Method of producing Quantum dots is to confine the electrons using electrodes. We start off with a layered structure which contains a quantum well and deposit narrow metal strips on the structure so as to define a square area . If we make all of the metals strips negatively charged then the electrons in the quantum well beneath the surface will be repelled . However, since they are confined to a thin layer which is parallel to the surface, the only direction they can move is side ways. As a result, the electrons are concentrated only into a tiny cluster directly underneath the central square defined by the electrodes . If we make this area small enough we can have a quantum dot. The interesting thing about this method is that we can control the number of dots by varying the voltage on the electrode . Whereas the shape of the quantum dots depends on the external electrodes and the barriers around the quantum well, which constrain the electron. around the quantum well, which constrain the electron....
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- Spring '10