Electrical behaviour of epitaxial Al/n-Al0.25Ga0.75As junctions: effect of the composition of undoped AlxGa1 - xAs cap layer

A method is presented for the evaluation of the Schottky barrier height phi(bO), the Richardson constant A*, the characteristic energy E(00), and the bias dependence of the barrier height beta from the temperature dependent current-voltage characteristics of Schottky junctions by using the thermionic-field emission (TFE) theory. This method is applied to experimental results measured in epitaxial Al/undoped AlxGa1-xAs/n-Al0.25Ga0.75. As junctions, and if is found that the current flow through these junctions is dominated by the TFE with anomalously high E(00). It is concluded 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 and/or DX centres.