Growth of epitaxial rare-earth arsenide/(100)GaAs and GaAs/rare-earth arsenide/(100)GaAs structures

Successful growth of (100)ErAs and (100)LuAs single crystal films on (100)GaAs has been demonstrated. Reflection high-energy electron diffraction, low-energy electron diffraction (LEED), cross-sectional transmission electron microscopy, x-ray diffraction, and Rutherford backscattering with channeling indicate single crystal growth. LEED patterns from the ErAs show a (1×1) structure. The overgrowth of ultrathin GaAs layers on ErAs and LuAs is difficult due to the poor GaAs wetting of the rare-earth arsenide surface, which results in three-dimensional growth. ErAs films thicker than 25 Å are semimetallic with a positive temperature coefficient of resistivity. The resistivity values are in the tens of μΩ cm range. Magnetotransport measurements at low temperature determined the electron and hole concentrations to be ∼1.8×1020 and ∼3.3×1020 cm−3 with mobilities of ∼1100 and ∼540 cm2 /V s, respectively. Electrically continuous buried ErAs films down to ∼7 Å have been made.