Nanoscale ErP islands on InP(001) substrate grown by organometallic vapor-phase epitaxy

We have investigated nanoscale ErP islands formed on InP(001) during Er exposure in organometallic vapor-phase epitaxial growth by means of atomic force microscopy and scanning tunneling microscopy. Different features of surface morphologies are observed depending on the growth temperature and the ErP coverage. The generation of misfit dislocation arrays along the [(1) over bar 10] direction leads to anisotropic strain relaxation that originates from the anisotropy of the atomic bonds at the interface. The residual strain of partially relaxed islands is similar to 2% for growth at 530 degrees C, which corresponds to the minimum of total areal energy of the strained him. Current imaging tunneling spectroscopy shows a high tunnel current at dislocations and ErP island edges suggesting the existence of high-density-surface states near the Fermi level and the decrease in tunneling barrier height.