Anomalous thermionic-field emission in epitaxial Al/n-AlGaAs junctions

We present a method for the evaluation of the Schottky barrier height phi(60), Richardson constant A*, characteristic energy E(infinity) and bias dependence of the barrier height beta from the temperature-dependent current-voltage characteristics of Schottky junctions using the thermionic-field emission (TFE) theory. The application of this method to experimental current-voltage characteristics of epitaxial Al/n-Al0.25Ga0.75As (N = 1.4 x 10(17) cm(-3)) barriers shows that the current now through these junctions is dominated by TFE with anomalously high E(infinity). We conclude that this anomaly may be partly connected with the electric field enhancement at the periphery of the diodes, and with the multistep tunnelling through deep levels.