CORRELATION BETWEEN BARRIER HEIGHT AND INTERFACE STRUCTURE OF AG/SI(111) SCHOTTKY DIODES

Barrier heights of Ag/n-Si(111)-''7 x 7'' and -1 x 1 Schottky contacts were determined from their current-voltage and capacitance-voltage characteristics. The zero-bias barrier heights were found to decrease proportional to the ideality factor. For ideal diodes with image-force-controlled ideality factors n(if) = 1.01, zero-bias barrier heights of 0.70 and 0.74 eV were obtained with Ag/n-Si(111)-''7 x 7'' and -1 x 1 diodes, respectively. The lower barrier heights of ''7 x 7''-reconstructed with respect to unreconstructed 1 x 1 interfaces are explained by the stacking fault in one of the triangular subunits of the ''7 x 7'' unit mesh. Stacking faults in bulk silicon are electrically neutral but are associated with electric dipoles. In ''7 x 7''-reconstructed metal/Si(111) contacts the fault-induced dipoles are oriented such that the respective barrier heights are lower than at unfaulted 1 x 1 interfaces.