{"term":{"id":"14005","title":"direct bandgap semiconductor","longtitle":"IUPAC Gold Book - direct bandgap semiconductor","doi":"10.1351\/goldbook.14005","code":"14005","status":"current","definitions":[{"id":1,"text":"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.","notes":{"1":"On photoexcitation, the electrons change their energy owing to the absorption of photons and maintain the same momentum."},"links":[{"term":"indirect bandgap semiconductor","url":"https:\/\/goldbook.iupac.org\/\/terms\/view\/14022"}],"sources":["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)"]}],"altoutputs":{"html":"https:\/\/goldbook.iupac.org\/terms\/view\/14005\/html","xml":"https:\/\/goldbook.iupac.org\/terms\/view\/14005\/xml","plain":"https:\/\/goldbook.iupac.org\/terms\/view\/14005\/plain"},"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","license":"The IUPAC Gold Book is licensed under Creative Commons Attribution-ShareAlike CC BY-SA 4.0 International (https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/) for individual terms.","collection":"If you are interested in licensing the Gold Book for commercial use, please contact the IUPAC Executive Director at executivedirector@iupac.org .","disclaimer":"The International Union of Pure and Applied Chemistry (IUPAC) is continuously reviewing and, where needed, updating terms in the Compendium of Chemical Terminology (the IUPAC Gold Book). Users of these terms are encouraged to include the version of a term with its use and to check regularly for updates to term definitions that you are using.","accessed":"2026-05-07T00:06:59+00:00"}}