Optical and structural characterization of InGaAs/GaAs superlattices with increasing number of periods

Abstract

We have studied the evolution of photoluminescence (PL) and photoluminescence excitation (PLE) spectra together with X-ray double diffraction of a series of MOVPE grown In 0.16Ga 0.84As/GaAs strained layer superlattices (SLS) as the number of periods increases from 5 to 20 while the composition and the thickness of the layers remain constant (70 Å). The structural quality of the samples with a small number of periods is excellent whereas for those with a large number of periods the rocking curves and the photoluminescence linewidth show a non-gaussian line broadening attributed to inhomogeneous strain relaxation. In the strained superlattice several well resolved interminiband transitions are observed and can be easily fitted using the experimental structural parameters.