Static and growing InP and InAs surfaces: reflection-anisotropy spectroscopy under the conditions of solid-source MBE

This presentation gives a current overview of the results obtained in situ and in real time by reflection-anisotropy (RA) spectroscopy, and complement ed by RHEED, in the P-capable MBE machine at Sheffield. Recent work dedicat ed to InP and InAs, as less investigated materials, is examined. Particular emphasis is put on the different phases in the static surface-phase diagra ms, as well as the possibility to observe growth oscillations. The low-temp erature c(4 x 4) surface reconstruction on (001)InP displays a RA signature with P-dimers along [1 (1) over bar 0] as opposed to the conventional mode l derived from the GaAs case. The newly observed by RA spectroscopy gamma(2 X 4) phase in InAs, confirmed by other groups' calculations, appears as th e lowest temperature reconstruction observed in this material. The transiti on towards the less As-rich and higher temperature phase, beta(2 X 4), take s place over a wide temperature region, exhibiting a 'solid-solution'-type behaviour between the two phases. Monolayer growth oscillations in the time -resolved RA signal are observed for both InP and InAs. The RA signal shows that upon operating the group-m beam shutter the surface stoichiometry cha nges much quicker than one monolayer period. This is discussed in conjuncti on with existing literature on STM of static surfaces, and in the case of I nP a model for the sequence of the surface reconstructions during the monol ayer growth cycle is suggested. (C) 2000 Published by Elsevier Science S.A.