Title: direct bandgap semiconductor
Long Title: IUPAC Gold Book - direct bandgap semiconductor
DOI: 10.1351/goldbook.14005
Status: current

Definition
Semiconductor or dielectric materials whose first band-to-band transition occurs from the highest level in the valence band to the lowest level in the conduction band possessing the same electron momentum, i.e., \(\boldsymbol{p}_{\rm{max}} = \boldsymbol{p}_{\rm{min}}\), with \(\boldsymbol{p}_{\rm{max}}\) and \(\boldsymbol{p}_{\rm{min}}\) the momentum vectors of electrons of the highest level in the valence band and the lowest level in the conduction band, respectively.

Note
On photoexcitation, the electrons change their energy owing to the absorption of photons and maintain the same momentum.

Related Term
- indirect bandgap semiconductor: https://goldbook.iupac.org//terms/view/14022

Source
- PAC, 2011, 83, 931. 'Glossary of terms used in photocatalysis and radiation catalysis (IUPAC Recommendations 2011)' on page 947 (https://doi.org/10.1351/PAC-REC-09-09-36)

Other Outputs
- html: https://goldbook.iupac.org/terms/view/14005/html
- json: https://goldbook.iupac.org/terms/view/14005/json
- xml: https://goldbook.iupac.org/terms/view/14005/xml

Citation: Citation: 'direct bandgap semiconductor' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. 10.1351/goldbook.14005
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Accessed: 2026-05-07T00:07:21+00:00