STABILITY OF (114) AND (114) FACETS IN III-V COMPOUNDS UNDER USUAL MBE CONDITIONS

Tensile GaInAs layers grown by MBE on InP(001) with lattice mismatch o f -0.5% to -1.7% have been examined by transmission electron microscop y (TEM). Elastic relaxation occurs by drastic thickness modulations wh ich are built first on (114) and (11 (4) over bar) facets, then on (11 3) and (11 (3) over bar) facets. Many examples of spontaneous developm ent of(114) facets from (001) surface have also been reported by other groups. This is observed under usual MBE conditions and for various c hemical compositions and lattice mismatches, positive as well as negat ive, for instance in compressively strained (Ga)InAs islands grown on GaAs(001) or InP(001). This is discussed in terms of surface reconstru ction. It is suggested that (114) and (11 (4) over bar) facets could b e reconstructed in a way very similar to the usual 2 x 4 reconstructio n of the (001) GaAs-As surface which is considered very stable. This i s due to their crystallographic structure which involves exactly two g allium steps per 2 x 4 unit cell.