ORDER-DISORDER HETEROSTRUCTURE IN GA0.5IN0.5P WITH DELTA-E(G)=160 MEV

Ordering in Ga0.5In0.5P can be controlled by variations in the substra te temperature during organometallic vapor phase epitaxial (OMVPE) gro wth. Growth at 720 degrees C at a rate of 0.5 mu m/h is shown to produ ce completely disordered material, as evidenced by the transmission el ectron diffraction (TED) and the photoluminescene (PL) results. The or dering produced at a growth temperature of 620 degrees C is found to d epend strongly on the substrate misorientation, Transmission electron micrographs and TED patterns for misorientations of 0 degrees, 3 degre es, 6 degrees, and 9 degrees from (001) toward the [110] direction in the lattice show that increasing the misorientation from 0 degrees to 3 degrees leads to the elimination of one variant, the elimination of twin boundaries, and an overall increase in the degree of order. Furth er increases in the misorientation angle to 6 degrees and 9 degrees at this growth temperature lead to increasing disorder, although only on e variant is formed and the distance between antiphase boundaries (APB s) increases monotonically with increasing theta(m). This wide variati on in ordering behavior has allowed the growth of an order/disorder he terostructure for a substrate misorientation of 3 degrees. The heteros tructure consists of a Ga0.52In0.48P layer 0.5 mu m thick grown at 740 degrees C followed by an ordered layer 0.4 mu m thick grown at 620 de grees C. The X-ray diffraction results show that both layers are preci sely lattice-matched to the GaAs substrate. TED patterns show that the first layer is completely disordered and the top layer is highly orde red, with only a single variant. High resolution images indicate that the interface is abrupt, with no dislocations or other defects. 10 K P L shows two sharp and distinct peaks at 1.995 and 1.830 eV for high ex citation intensities. The peak separation is even larger at lower exci tation intensities. The two peaks come from the disordered and ordered material, respectively. The peak separation represents the largest en ergy difference between ordered and disordered material reported to da te. This large energy difference, 6.6kT at room temperature, may make such heterostructures useful for photonic devices such as light emitti ng diodes, lasers, and solar cells.