Electronic structure and conduction in a metal-semiconductor digital composite:: ErAs:InGaAs

We have grown epitaxial superlattice structures of layers of semimetallic ErAs particles embedded in an InGaAs matrix on (001) Fe-doped InP substrates. Temperature-dependent Hall measurements, x-ray diffraction, and transmission electron microscopy were performed on the materials. The carrier mobility and the temperature dependence of the charge density imply conduction in the InGaAs matrix. We calculate an offset between the conduction-band minimum of the InGaAs matrix and the Fermi level of the ErAs particles that is strongly dependent on the amount of ErAs deposited. As the size of the ErAs particles increases, the Fermi level decreases from similar to0.01 eV above the InGaAs conduction-band edge to similar to0.2 eV below the InGaAs conduction-band edge and the electrical conduction properties change from metallic to semiconducting. (C) 2001 American Institute of Physics.