EFFECTS OF TENSILE STRAIN AND SUBSTRATE OFF-ORIENTATION ON THE GROWTHOF GAINAS INP MULTIPLE-QUANTUM-WELL STRUCTURES BY CBE/

GaInAs/InP multiple quantum well (MQW) layers with high tensile strain in the GaInAs layers have been grown by chemical beam epitaxy (CBE). The samples were analysed by high-resolution X-ray diffraction (XRD), photoluminescence (PL) spectroscopy and transmission electron microsco py (TEM). The influence on layer properties of the tensile strain and the substrate off-orientation of the (100) InP substrates is investiga ted. XRD studies reveal that the growth rate of GaInAs as well as that of InP is larger for off-oriented substrates than for exactly oriente d substrates. This behaviour is independent of the strain in the GaInA s layers and of the growth temperature in the chosen range between 485 degrees C and 545 degrees C. We attribute the observed changes of the growth rate to the different growth modes on exact (100) and off-orie nted substrates. MQW structures grown on off-oriented substrates show a linear increase of the PL line width of the GaInAs MQW peak with inc reasing tensile strain in the GaInAs layers. In contrast, it stays con stant for exactly oriented substrates. This increase in the PL line wi dth for off-oriented substrates is explained by the lattice tilting oc curring when strained layers are deposited on stepped surfaces. The ti lt angle is proportional to the amount of incorporated elastic strain as shown by the azimuthal dependence of the position of the zeroth-ord er satellite reflection in XRD.