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Semiconductor nanotechnology: quantum dots. Micheal Robinson, Micheal McGlen , Will Parr and Josh Conneely. Semiconductors – Micheal. Insulators. Insulators - explained. Insulators have tightly bound electrons in their outer shell

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## Semiconductor nanotechnology: quantum dots

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**Semiconductor nanotechnology: quantum dots**Micheal Robinson, MichealMcGlen, Will Parr and Josh Conneely**Insulators**Insulators - explained Insulators have tightly bound electrons in their outer shell These electrons require a very large amount of energy to free them for conduction Let’s apply a potential difference across the insulator above… The force on each electron is not enough to free it from its orbit and the insulator does not conduct Insulators are said to have a high resistivity / resistance**Insulator – conductor transition**However, if we apply a little heat to the silicon…. An electron may gain enough energy to break free of its bond… It is then available for conduction and is free to travel throughout the material**We have positive charges too!**Let’s take a closer look at what the electron has left behind There is a gap in the bond – what we call a hole Let’s give it a little more character…**Lights – Einstein and Planck**• 1905 Einstein –related wave and particle properties of light • Planck - WAVE-PARTICLES DUALITY E = h Total E of the Photon (particle side) Frequency (wave side) • Light is emitted in multiples of a certain minimum energy unit. The size of the unit – photon. • Explain the photoelectric effect - electron can be emitted if light is shone on a piece of metal • Energy of the light beam is not spread but propagate like particles e**Bohr’s model**The electron is a wave, it must traverse an integer number of waves in a single orbit of the proton.**Quantum dots**A quantum dot is a ‘blob’ of one semiconductor embedded in another. The blob is so small that its length scale is close to the electron’s wavelength – so electrons behave as waves.**Quantum dots from Lancaster**20nm Electrons are used to image individual atoms…**Quantum networks**Entangled photon source Quantum memory To build a secure quantum network we’ll need to be able to store single photons without ‘reading’ them, a quantum repeater. We intend to develop a cheap, scalable repeater using quantum dots.

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