Saturated low-temperature conductivity in ultrafast semiconductor nanocomposites

摘要

This Letter presents studies on low-field electrical conduction in the range of 4-300 K for an ultrafast material, i.e., InGaAs:ErAs grown by molecular beam epitaxy. The unique properties include nano-scale ErAs crystallites in the host semiconductor InGaAs, a deep Fermi level and picosecond ultrafast photocarrier recombination. As the temperature drops, the conduction mechanisms are in the sequence of:thermal activation, nearest-neighbor hopping, and variablerange hopping. In the low-temperature limit, finite-conductivity metallic behavior, not insulating, was observed. This unusual conduction behavior, related to the nanometerscale ErAs crystallite islands, is explained with the Abrahams scaling theory. Current vs. temperature for (A) InGaAs:ErAs - the ultrafast nanocomposite; and (C) an undoped InGaAs.