Electron tunneling through GaAs grain boundaries

Measurements of the zero-bias dc conductance G0 and high frequency capacitance have been made on GaAs bicrystals doped in the range of 4×1017–2×1018 cm−3. The conductance displays a non-Arrhenius temperature dependence with high temperature values of ∂(ln G0)/∂(1/kT) less than the barrier heights deduced from the capacitance. Theoretical calculations of transbarrier currents using the unified approach of Fonash show that thermally assisted tunneling currents are important.