Talk:Indirect bandgap

Is this entirely correct: "Indirect bandgap semiconductors can absorb light, however this only occurs for photons with significantly more energy than the bandgap."

Couldn't an indirect semiconductor absorb a photon with the bandgap energy, if the momentum vector of the photon was just right? --User:Dgrant

No, because the momentum of a photon is very small compared to the momentum offset between CB and VB. Radiative transitions appear as very nearly vertical lines on the E-k diagram. Radiative recombination and emission is possible with the help of a well-placed phonon, but such events are very unlikely. In practice, conduction band electrons in silicon are de-excited via traps. -- Tim