Interfacial modulation on single-crystalline aluminum films grown on GaAs by ErAs insertion

Single-crystalline aluminum (Al) films are grown on GaAs (100) substrates by molecular beam epitaxy. The Al/GaAs interface is modified by ErAs insertion, and the Al quality is further improved. The full-width at half-maximum for Al (111) diffraction peak is 0.06°, and the root-mean-square surface roughness is 0.69 nm. In addition, the Al growth orientation can be tuned by ErAs insertion, which is attributed to the smaller lattice mismatch and higher surface symmetry provided by ErAs. The interfacial interdiffusion between Al and GaAs can be suppressed by ErAs as well. The sharp interfaces as well as the high quality of Al are confirmed by cross-sectional transmission electron microscopy studies. The lattice arrangements of the two stable Al/GaAs and Al/ErAs structures are proposed to show that the lattice matching and the interfacial bonding are two main driving forces.