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Photoluminescence properties of short-period asymmetric GaAs/AlAs superlattices with the well and barrier thickness varied from 10 to 3 monolayers were studied at high optical excitation. It was shown that an asymmetric structure of the superlattice, in which the well layers are at least twice wider than the barrier ones, allows us to maintain the direct band gap and, hence, to improve emission properties for any well width. This is important for utilization of such structures in light-emitting devices. The stimulated emission at 80 K was observed for a GaAs/AsAs superlattice with the well and barrier thickness of 6 and 3 monolayers, respectively. At the same time, investigations of the dependences of the emission intensity on the pump intensity for different superlattices revealed an enhancement of nonradiative recombination with decreasing the well thickness due to an enhanced influence of interface roughness.
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