We investigate the embedded interfaces of GaAs/AlGaAs quantum wells grown by metal organic vapor phase epitaxy on slightly (< 1 degrees)-misoriented (001) substrates using selective etching and atomic force microscopy. Depending on the substrate misorientation, we observe different growth modes at the embedded interfaces, which are directly correlated to the photoluminescence linewidth. We show that the narrowest linewidth is obtained on 0.2 degrees-off (001) substrates for which the heterointerfaces consist of atomically smooth narrow terraces. We investigate the embedded interfaces of GaAs/AlGaAs quantum wells grown by metal organic vapor phase epitaxy on slightly (< 1 degrees)- misoriented (001) substrates using selective etching and atomic force microscopy. Depending on the substrate misorientation, we observe different growth modes at the embedded interfaces, which are directly correlated to the photoluminescence linewidth. We show that the narrowest linewidth is obtained on 0.2 degrees-off (001) substrates for which the heterointerfaces consist of atomically smooth narrow terraces. (c) 2006 American Institute of Physics.