The Crystalline quality of InxAl1-xAs layers on lnP grown by molecular beam epitaxy at 520 degrees C

The crystalline quality of InxAl1-xAs (x = 0.52, 0.489, 0.476) layers grown by molecular beam epitaxy (MBE) on InP substrate at 520 degrees C has been studied. From the double crystal x-ray diffraction and photoluminescence m easurement, InxAl1-xAs (x = 0.52, 0.489) layers have been found to reveal h igh quality crystallinity and excellent optical performance. Although the I n0.489Al0.511As layer of thickness of 1.116 mu m has a lattice mismatch of 0.23%, an excellent lattice coherency has been achieved. On the other hand, in the In0.476Al0.524As layer which has only a slightly larger lattice mis match of 0.32%, stacking faults are observed. We have also observed the mod ulation contrast in planar view images obtained from transmission electron microscopy, which most likely arises due to the clustering of In or Al atom s. The modulation has a wavelength of about 8 nm independent of the lattice mismatch between the substrate and the epilayer. (C) 2000 Kluwer Academic Publishers.