Difference between revisions of "Quantum well"
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A quantum well works in a very similar way. Electrical forces keep charged particles (such as [[electron]]s) inside the well, just like [[gravity]] keeps a ball inside the Grand Canyon. | A quantum well works in a very similar way. Electrical forces keep charged particles (such as [[electron]]s) inside the well, just like [[gravity]] keeps a ball inside the Grand Canyon. | ||
| − | A second important difference is that quantum wells are very small (about 1000th of the width of a human hair). At these scales, [[quantum mechanics|quantum effects]] come into play. This means that the electron may only have certain, fixed energy | + | A second important difference is that quantum wells are very small (about 1000th of the width of a human hair). At these scales, [[quantum mechanics|quantum effects]] come into play. This means that the electron may only have certain, fixed [[energy level]]s. Think of this as being like standing on a ladder - you can only stand on the rungs, not the gaps in-between. |
== Why this is useful == | == Why this is useful == | ||
Revision as of 15:13, March 20, 2009
A quantum well is a device for storing electrons or other charged particles. They are used in many different types of modern technology, including computers, lasers and solar panels.
How it works
Imagine a ball rolling into the Grand Canyon, it will fall to the bottom and cannot get back out unless a lot of energy is used (for example, someone at the bottom of the well could fire it out of a cannon!).
A quantum well works in a very similar way. Electrical forces keep charged particles (such as electrons) inside the well, just like gravity keeps a ball inside the Grand Canyon.
A second important difference is that quantum wells are very small (about 1000th of the width of a human hair). At these scales, quantum effects come into play. This means that the electron may only have certain, fixed energy levels. Think of this as being like standing on a ladder - you can only stand on the rungs, not the gaps in-between.
Why this is useful
Einstein won a Nobel prize by showing that the energy in a beam of light is actually contained in lots of small packets called photons, rather than being spread out evenly in the beam. The energy stored in each photon depends on the colour of the light.
The electron may only take certain, fixed energies inside the quantum well. This means that the electron can only absorb or release fixed amounts of energy (or certain colours of light). This makes quantum wells extremely useful in devices which convert a particular colour of light to electricity (or vice versa), such as lasers, LEDs and solar panels.