Heterostructures comprising highly strained GaAs quantum wells in Al0.48In0.52As and Ga0.47In0.53As layers have been grown by the metalorganic chemical vapor deposition method on InP(100) substrates. The photoluminescence spectra of these structures have been studied, and it is established that GaAs quantum wells form type-I heterojunctions with Al0.48In0.52As layers and type-II heterojunctions with Ga0.47In0.53As layers.