IN-SITU MONITORING OF THE SURFACE RECONSTRUCTIONS ON INP(001) PREPARED BY MOLECULAR-BEAM EPITAXY

Reflection anisotropy spectroscopy (RAS) and reflection high-energy el ectron diffraction (RHEED) were applied to study clean InP(001) surfac es prepared by molecular beam epitaxy (MBE). At phosphorus beam equiva lent pressures (BEPs) between 3.5x10(-7) and 3.5x10(-6) mbar and subst rate temperature (T-S) falling from 590 to 150 degrees C, (2x4), (2x1) , (2x2), and c(4x4) RHEED patterns are observed. The main RAS features , observed at 1.7-1.9 and 2.6-2.9 eV are assigned to In and P dimers, respectively. The above reconstruction sequence is associated closely with transformations identified in RAS signatures that are induced by progressively increasing the P surface coverage. The RAS results also imply the existence of (2x4)alpha and (2x4)beta phases. A surface-phas e diagram for MBE-grown (001) InP, in the whole range of T-S and phosp horus BEPs is proposed. (C) 1997 American Institute of Physics.