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ericmazur / PnPbook

Tracking of typos, errors, and improvements for "The Principles and Practice of Physics"
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intrinsically wrong #184

Open JohnDenker opened 8 years ago

JohnDenker commented 8 years ago

In chapter 32 in the chapter summary (aka «glossary») an intrinsic semiconductor is allegedly defined to be made of atoms of one element only. This is not correct. In reality, intrinsic means simply no mobile carriers. Reference: See e.g. https://inst.eecs.berkeley.edu/~ee105/fa05/handouts/discussions/Discussion1.pdf which is perfectly happy to discuss the properties of intrinsic GaAs.

Earlier in the chapter, the definition on page 849 is ambiguous ... not so obviously wrong, but also not obviously correct, and certainly not clear.

JohnDenker commented 8 years ago

Suggestion:

This is the sort of issue that can be handled by a footnote or a gloss ... not a glossary, but an old-school gloss, on the page in question.

Specifically: Possible rewording:

The defining property of an intrinsic semiconductor is that it has no mobile carriers (in equilibrium, in the low-temperature limit). As a result, it has rather low conductivity ... low compared to other semiconductors, and very low compared to good metals (but still not as low as a proper insulator). The simplest(*) way to achieve this is by using an extremely pure crystal of a single element, such as pure silicon.

(*) Footnote: there are other ways of achieving this, for example an extremely pure compound such as gallium arsenide. The details are beyond the scope of the course.