Modelling electrical behaviour of nonuniform AlSi Schottky diodes

The heat-treated AlSi contacts show large nonuniformities and cannot be described by a one-dimensional theory. The authors partially succeed in describing circular Al/ n Si contacts by a crude model: two diodes in parallel (the first central and circular, the second peripheral and annular). It was shown that only a part of the contact area is effective for samples treated at lower temperatures, due to the interfacial oxide layer. However, the contacts treated at 550°C seem to have more or less uniform electrical properties, despite large nonuniformities in the contact geometry. Moreover, the effective energy barrier of these contacts is little influenced by the preparation conditions, including the amount of Al available for AlSi interaction and the rate of cooling. These results may modify the present conception of the formation of the Al-doped layer at the AlSi interface.