Boltzmann factor for a gap. Very small numbers, but compare with Avogadros number. For large gaps, not even the Avogadro can compensate. Nearly pure zero in the conduction band - insulator. Electrons and holes. Semiconductoe conductivity    i n c r e a s e s    with temperature. Demonstrations of energy gap: electrical conductivity, photoconductivity, or simply absorption of photons. Phonon assisted photoabsorption.

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