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  • Rights: The University of Waikato
    Published 30 May 2008 Referencing Hub media
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    Dr Richard Tilley of Victoria University of Wellington describes what silicon1 quantum dots are and outlines some applications.

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    DR RICHARD TILLEY
    Quantum dots and nanoparticles are semiconductor2 materials, so typical semiconductors are things like silicon or germanium. And the fantastic thing about quantum dots is that they have different properties compared to the bulk materials because of their small size. So one of the materials we are looking at is silicon, and a big piece of silicon just looks like a piece of metal3 – it’s very shiny and silvery. But when we make our silicon particles, we make them of only about 1.5 nanometres, so they really are minute. They are made up of maybe only 50 to 100 atoms. And when we make our silicon particles this small, we can actually get them to emit light, which bulk silicon will not do, and then we can use this property4 for different applications. To be able to see the quantum dots, what we have to do is shine some light onto them, some high energy light, say UV light5, and then they will give out the different colours that we want to see. People are researching applications for them as light emitting diodes6, or for lighting or even television screens, but what we are interested in is looking at biological applications for them.

    Acknowledgements:
    Professor Kenji Yamaoto

    1. silicon: A semimetal – symbol Si, atomic number 14.
    2. semiconductor: A substance that can be made to conduct or block electricity. Silicon is a semiconductor that forms the basis of computer chips and many electronics components.
    3. metal: Any of a category of elements that usually have a shiny surface, are generally good conductors of heat and electricity and can be melted or fused, hammered into thin sheets or drawn into wires (for example, copper).
    4. property: A physical or chemical property is a physical or chemical state of a substance that can be measured. Any changes can be used to describe transformations between states.
    5. UV (ultra violet) light: Light that is invisible to the human eye and at a wavelength between 300–400 nanometres. UV light is what causes sun burn and can cause some types of cancer.
    6. light-emitting diode: Light-emitting diode, or more as it is commonly referred to LED, is a semiconductor device that gives off light when current passes through it in one direction only.
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      silicon

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    2. A semimetal – symbol Si, atomic number 14.

      property

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    4. A physical or chemical property is a physical or chemical state of a substance that can be measured. Any changes can be used to describe transformations between states.

      semiconductor

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    6. A substance that can be made to conduct or block electricity. Silicon is a semiconductor that forms the basis of computer chips and many electronics components.

      UV (ultra violet) light

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    8. Light that is invisible to the human eye and at a wavelength between 300–400 nanometres. UV light is what causes sun burn and can cause some types of cancer.

      metal

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    10. Any of a category of elements that usually have a shiny surface, are generally good conductors of heat and electricity and can be melted or fused, hammered into thin sheets or drawn into wires (for example, copper).

      light-emitting diode

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    12. Light-emitting diode, or more as it is commonly referred to LED, is a semiconductor device that gives off light when current passes through it in one direction only.