BEHAVIOR OF VICINAL INP SURFACES GROWN BY MOVPE - EXPLOITATION OF AFMIMAGES

InP substrates and epilayers grown by MOVPE have been studied by AFM. For different misorientation angles, we observed the surface of the su bstrate after annealing under phosphine (PH3) and of the epilayers und er different growth conditions such as growth temperature T-g and trim ethylindium (TMI) partial pressure. After annealing the terrace width corresponds to the nominal value of misorientation angle measured by X -ray diffraction. We observed different topographies and roughnesses f or the grown layers corresponding to different growth modes. We propos e, taking into account the roughness of the surface, a calculation of the step height and terrace width. For 2D nucleation (theta less than or equal to 0.2 degrees and T-g=500 degrees C) and step flow mode, the roughness is low while it is increased by step bunching (theta greate r than or equal to 0.5 degrees and T-g greater than or equal to 580 de grees C). Moreover we have examined the surface morphology for differe nt misorientation angles and determined the influence of growth condit ions (growth temperature, indium partial pressure) on the growth mecha nism. At T-g=580 degrees C the increase of the TMI partial pressure in the reactor enhances the step bunching and leads to larger terraces.