The direct current (de) conductivity of Al-(Ge-S-Ga)-Al samples has been investigated at high applied electric fields up to 1 . 10(8) V m(-1) at room temperature, and the electrical transport in the thermionic and thermionic-field emission modes. From the current-voltage characteristics, the values of the electron work function chi at the Al/Ge-S-Ga interface, the relative dielectric permittivy epsilon of the layers and the effective electron mass m(c)/m in the conduction band have been determined. The experimental results are in agreement with Christov’s theory for injected electron currents through the potential barrier.