Published online by Cambridge University Press: 28 February 2011
In heavily dislocated GaAs (dislocation density of 108cm-2), the low-temperature cathodo- luminescence efficiency of quantum wells and superlattices is dramatically higher than that of a bulk-like layer. Furthermore, the luminescence efficiency can be further improved by doping the barriers of the GaAs/(Al,Ga)As multi-quantum well structures with beryllium (Be). Two quite different possible models for this observation are discussed: One assumes that the effect is due to the expulsion of dislocation kinks from the wells, the other that it is due to the effect of well width fluctuations.