Characterization of unicompositional GaInP₂ ordering heterostructures grown by variation of V/III ratio

Photoluminescence (PL) and photoluminescence excitation (PLE) spectroscopies are employed to investigate single heterostructures based on two GaInP₂ layers that have the same composition but different degrees of order on the cation sublattice. Four sample configurations are studied: two complementary single heterostructures, a more ordered layer grown on a less ordered layer and vice versa, and two single layers nominally equivalent to the constituent layers of the heterostructures. The degree of order of the two layers was controlled via the V/III ratio used during organometallic vapor phase epitaxial growth. From our measurements, the difference between the band gaps of the two layers is 20-30 meV. The PLE spectra show clearly that the emission comes from both layers of the heterostructures and that the PL is excited by direct absorption of the exciting light into each layer as well as the injection of carriers from the less ordered (higher band gap) layer into the more ordered (lower band gap) layer. The data clearly show that the heterostructures contain two layers, each very similar to the corresponding single layer sample.