Re: HOLES AS CARRIERS

[John Clement <clement@HAL-PC.ORG>]

> William Beaty wrote:
>
> > In truth, a hole acts to "expose" the positive charge of the
> > silicon's protons which normally would be canceled out.
> > It's easy to concentrate on the emptiness of the "hole"
> > while forgetting that a hole is most definitely a positive
> > charge carrier.
>
> Ludwid Kowalski wrote:
>
> After being satisfied with the explanation of the "positivity
> of holes" I started thinking about it and I am less satisfied.
> All materials are made of atoms, systems containing
> charged particles (electrons and protons). We learn that
> there are no particles called holes, unless the "emptiness",
> full of fields, is treated as a set of holes.

It think that the distinction between holes and "real" particles may be
resolved by thinking of holes as carriers of net charge.  Charge is actually
a property of a particle that allows us to calculate what happens to that
particle in the presence of other charged particles.  The hole is a carrier
of net positive charge which physically means that it "looks like" a
positive particle.  A hole contains an excess of postive particles (more
protons than electrons).  With this model one can understand what is
happening in a semiconductor.

This brings up the the idea that the usage of holes is a model.  It is a
means of making sense of what is happening under a variety of conditions.
Whether the model is a picture of "reality" is in a sense irrelevant.  One
should then tie this model to other models such as the particle model of
having nucleii and electron in the substance.  One would not use the
particle model to do actual calculations because it is too complicated.  We
deal with many models, but there is a tendency for human beings to
categorize some models as "realistic" and others as artificial.  Scientists
must learn to use appropriate models for the physical situation they are
analyzing, no matter whether they think the model is real or unreal.  I
should point out that the idea of force is also a model, as are phonons,
valence ...


John M. Clement
Houston, TX