Term: bending of energy bands https://doi.org/10.1351/goldbook.B00629 Definition: The distribution of potential in the space charge region of a semiconductor results in a change in the electron energy levels with distance from the interface. This is usually described as 'bending of the energy bands'. Thus the bands are bent, upwards if σ > 0 and downwards if σ < 0, where σ is the free charge density. When σ = 0 the condition of flat bands is met, provided no surface states are present. Related Terms: 1) semiconductor (http://doi.org/10.1351/goldbook.S05591). 2) interface (http://doi.org/10.1351/goldbook.I03082). 3) charge density (http://doi.org/10.1351/goldbook.C00988). 4) surface states (http://doi.org/10.1351/goldbook.S06190). Source: PAC, 1986, 58, 437. 'Interphases in systems of conducting phases (Recommendations 1985)' on page 443 (https://doi.org/10.1351/pac198658030437) Citation: 'bending of energy bands' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.B00629 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. 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.