bandgap energy, Eg

https://doi.org/10.1351/goldbook.B00593
The energy difference between the bottom of the
conduction band
and the top of the
valence band
in a
semiconductor
or an insulator.
See:
conduction band
,
Fermi level
Source:
PAC, 1996, 68, 2223. (Glossary of terms used in photochemistry (IUPAC Recommendations 1996)) on page 2229 [Terms] [Paper]