OPTICAL-PROPERTIES OF SYMMETRICALLY STRAINED (GAIN)AS GA(PAS) SUPERLATTICES GROWN BY METALORGANIC VAPOR-PHASE EPITAXY/

Symmetrically strained (GaIn)As/Ga(PAs) superlattice structures (symm. SLS) have been realized by metalorganic vapour phase epitaxy (MOVPE). The high structural as well as optical quality of these symm. SLS has been established by detailed high-resolution X-ray diffraction (XRD) and in particular photoluminescence (PL) and excitation spectroscopy ( PLE) investigation. The optical recombination of low temperatures is d ue to excitons localized in statistical potential fluctuations in the (GaIn)As well layer. The excition binding energy is determined in thes e symm. SLS to (5.5 +/- 1) meV according to a theoretical description of the PLE spectra usign a two-dimensional (2D) absorption model. Ther efore, the excition binding energy is significantly reduced as compare wd to unstrained GaAs quantum wells, caused by a considerably smaller in-plane hole mass for the top most valence subband. An estimate of th is mass based on the determined exciton binding energy yields a value of about 0.05 m0.