OPTICAL ANISOTROPIES OF INP(001) SURFACES

Metalorganic vapor phase epitaxy grown InP samples capped with a prote ctive As/P double layer were used to study clean (001) surfaces in ult rahigh vacuum. By the thermal desorption of As and P cap layers, InP s urfaces producing sharp 2x4 low energy electron diffraction (LEED) pat terns were prepared. The reconstructed surface and intermediate prepar ation stages were studied by using reflectance anisotropy spectroscopy (RAS), LEED, and Auger electron spectroscopy. Features in the optical anisotropy related to the contribution of P-P and In-In surface bonds are identified and discussed. The results show that the surface-relat ed optical anisotropy of the 2x4 In-rich reconstruction of InP(001) is due to In-In bonds along the [110] direction that produce a large opt ical anisotropy below 2 eV. Furthermore, at intermediate annealing sta ges, information by RAS on a P-rich 1x1 reconstructed phase was obtain ed. The contribution of P dimers to surface reflectance anisotropy abo ve 3 eV is discussed. (C) 1997 American Institute of Physics.