Assertion: indirect bandgap semiconductor | /r/HasProperty | inefficient emitters
Facets:
value: very
type: DEGREE
value: usually
type: DEGREE
Source sentences:
text: A phonon is required in the process of absorption or emission in the case of an indirect bandgap semiconductor, so indirect bandgap semiconductors are usually very inefficient emitters, although they work reasonably well as absorbers also (as with silicon photovoltaics).