MICROSTRUCTURES OF INAS1-XSBX (X=0.07-0.14) ALLOYS AND STRAINED-LAYERSUPERLATTICES

Growth of InAs1-xSbx alloys by metalorganic chemical vapor deposition at 475 degrees C results in CuPt ordering even at Sb concentrations as low as x = 0.07-0.14. The two ({111}(B) variants are present, but eac h exists separately in 1-2 mu m regions. However, the ordering is inco mplete: it occurs in platelet domains lying on habit planes tilted 30 degrees from (001) within a disordered matrix and is not continuous at the atomic scale within the domains. This ordering apparently explain s the reduction in infrared emission energies relative to the bandgaps of bulk alloys. Similar ordering is found in an InAs0.91Sb0.09/In0.87 Ga0.13As strained-layer superlattice with lower-than-expected emission energy. High-resolution images indicate that the superlattice layers flat and regularly spaced. Infrared LEDs have been made from such supe rlattices.