Microstructure formation during MnAs growth on GaAs(001)

A comprehensive study of the GaAs(001)/MnAs interface formation and of the MnAs layer evolution during MBE growth has been performed in situ by RHEED and RDS and after growth by TEM. For low growth rates and high As-4/Mn flux ratios we find a perfect ((1) over bar 00) epitaxial orientation with [00. 1]MnAs parallel to[(1) over bar 10]GaAs (A-orientation). The formation of B -domains with 90 degrees azimuthal rotation, detected during growth, is res tricted to thicknesses up to 7 nm. TEM studies on the as-grown samples only reflect the X-orientation connected with an atomically abrupt interface st ructure. The large lattice mismatch between MnAs and GaAs is accommodated b y the generation of misfit dislocations with different character along perp endicular directions. Magnetization measurements revealed promising magneti c properties. (C) 1999 Elsevier Science B.V. All rights reserved.