SURFACE-STRUCTURE OF INP(001) UNDER DYNAMIC AND STATIC CONDITIONS OF MOLECULAR-BEAM EPITAXY

A combined study, using reflection high energy electron diffraction (R HEED) and reflection anisotropy spectroscopy (RAS), has been carried o ut on clean (001)InP surfaces prepared in a solid-source molecular bea m epitaxy (MBE) reactor. Experiments performed under non-growing (stat ic) conditions show the existence of a number of surface reconstructio ns, including two distinctive (2 X 4) phases at higher substrate tempe ratures. As the temperature is decreased (2 X 1), (2 X 2) and c(4 x 4) reconstructions are found. The c(4 X 4) reconstruction, observed for the first time, has a significantly different RA signature than that f ound for GaAs, indicating that a different surface model is necessary in this case. The RHEED patterns and RA spectra recorded for the growi ng (dynamic) InP surface are similar to that of the static surface, wi th the RA-signal differences between the two being accountable by the effective change in the P-2 overpressure at the surface. Under convent ional growth conditions, we have observed monolayer oscillations in th e RA signal during the initial stages of InP epitaxy for the first tim e. (C) 1998 Elsevier Science B.V.