| Indirect Bandgap |
Article Index for Indirect |
Information AboutIndirect Bandgap |
| CATEGORIES ABOUT INDIRECT BANDGAP | |
| condensed matter physics | |
| semiconductors | |
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Semiconductors that have an indirect bandgap are inefficient at emitting Light . This is because any Electron s present in the conduction band quickly settle into the energy minimum of that band. Electrons in this minimum require some source of momentum allowing them to overcome the offset and fall into the Valence Band . Photon s have very little momentum compared to this energy offset – hence, the momentum "kick" of a photon being emitted would normally not be enough to dislodge the electron from the conduction band. Since the electron cannot rejoin the valence band by Radiative Recombination , conduction band electrons typically last quite some time before recombining through less efficient means. Silicon is an indirect bandgap semiconductor, and hence is not generally useful for Light-emitting Diode s or Laser Diode s. Indirect bandgap semiconductors can absorb light, however this only occurs for photons with significantly more energy than the bandgap. This is why pure silicon appears dark grey and opaque, rather than clear. EXTERNAL LINKS
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