K-12: Introduction to Quantum Wells

By David Beck1, Mark M Budnik1

1. Valparaiso University

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    Tanya Faltens

    2.0 out of 5 stars

    This activity presents the idea of one of _functions_ of a quantum well -- that it can act a memory storage element, quite well.

    - States are defined by whether a well is occupied (1) or empty (0)

    However, the lesson provides some explanations and activities on the _process_ of tunneling, and the fundamental _nature_ of electrons, that are disconnected from the way tunneling, and electrons in Qdots, are typically discussed and represented.  Models are always simplifications, so break down in certain areas, and sometimes in education we sacrifice some errors for simplification.  I don't think that the erroneous simplifications are helpful in this case, but do think that the correct parts of this lesson could still be presented, without the erroneous parts.

    The errors, I think, stem from attempting to describe a quantum mechanical effect that depends on the wave nature of electrons using a particle-viewpoint. 

    Here are my responses to the main statements in the lesson that are scientifically incorrect:

    1 - Electrons do not tunnel by going "in-between atoms" --In other words, they do not have to be lined up at the right position to tunnel-- tunneling can happen at any position if the barrier (row of atoms) is thin enough.  Tunneling is best described by quantum mechanics, not classical mechanics.

    2 - Electrons do not "bounce around" inside a quantum well the way billiard balls bounce around a billiard table.  At this length scale, electrons exhibit more wave nature than their particle nature.

    Changing the instructions and focusing on a different aspect of the lesson might make it work better.   Perhaps if someone is really creative they can suggest a way to representing the wave nature of electrons using kids.  There are a lot of users of this resource, it would be great to get some additional input from the community.

    My rating is low because of the scientific inaccuracies in the material.

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