It was pointed out that ordering in Ga0.5In0.5P could be controlled by varying the substrate temperature during organometallic vapor phase epitaxial growth. Growth at 720C, at a rate of 0.5/h, was shown to produce completely disordered material; as revealed by transmission electron diffraction and photoluminescence results. The ordering which was produced at a growth temperature of 620C was found to depend strongly upon the substrate misorientation. Transmission electron micrographs and transmission electron diffraction patterns for misorientations of 0, 3, 6 and 9, from (001) and towards [110], showed that increasing the misorientation from 0 to 3 led to the elimination of 1 variant, to the elimination of twin boundaries, and to an overall increase in the degree of order. Further increases in the misorientation angle, to 6 or 9, at this growth temperature led to increasing disorder; although only 1 variant was formed and the distance between antiphase boundaries increased monotonically with increasing angle. This wide variation in ordering behavior permitted the growth of an order-disorder heterostructure at a substrate misorientation of 3. The heterostructure consisted of an 0.5-thick Ga0.52In0.48P layer which was grown at 740C, followed by an 0.4-thick ordered layer which was grown at 620C. The use of X-ray diffraction showed that both layers were precisely lattice-matched to the GaAs substrate. Transmission electron diffraction patterns showed that the first layer was completely disordered and that the top layer was highly ordered, with only a single variant. High-resolution images indicated that the interface was abrupt, with no dislocations or other defects. The photoluminescence at 10K exhibited 2 sharp and distinct peaks (1.995, 1.830eV) under high excitation intensities. The peak separation was even larger under lower excitation intensities. The 2 peaks arose from the disordered and ordered material, respectively. The peak separation reflected the largest energy difference (6.6kT at room temperature), between ordered and disordered material, which had been reported so far.

L.C.Su, I.H.Ho, N.Kobayashi, G.B.Stringfellow: Journal of Crystal Growth, 1994, 145[1-4], 140-6