Observation of one-monolayer size fluctuations in a GaAs/GaAlAs superlattice

The observation of one-monolayer well size fluctuations in a superlattice is reported. Luminescence experiments show that several exciton peaks occur, each of them corresponding to a discrete well width differing by one monolayer from the next one. This attribution is confirmed by the intentional introduction of a larger well in the structure. It is also checked by comparison with the x-ray diffraction results that confirm the variations of the superlattice parameters observed in luminescence, and by photoluminescence excitation experiments that also show a splitting.