We report on photoluminescence (PL) studies of GaInP epilayers and GaInP/AlGaInP quantum well (QW) heterostructures grown by solid-source molecular beam epitaxy (SS-MBE) on GaAs substrates, which were cut exactly along the (1 0 0) plane or deliberately misoriented 10degrees towards [1 1 0], [1 1 1]A, and [1 1 0] directions. Closely optimal growth conditions were determined for the samples. The strongest emission from GaInP epilayers was obtained when growth temperature and phosphorus beam equivalent pressure (BEP) were around 520degreesC and 2 x 10(-5) mbar, respectively, quite independent of whether the substrate was cut along (1 0 0) or 10degrees off towards [1 1 1]A. This surface also produced the strongest emission from the QWs grown at 490degreesC with BEP approximate to 1 x 10(-5) mbar. It was observed that the epilayers on the (1 0 0)-0degrees surfaces exhibited an enhanced alloy order effect, which red-shifted the PL spectra. Impurity oxygen, likely originating from the phosphorus charge, deteriorated emission especially from the misoriented surfaces. (C) 2004 Published by Elsevier B.V.