Comparative study of I-V characteristics of the ICB deposited Ag/n-Si(111) and Ag/p-Si(100) Schottky junctions

The room temperature I-U characteristics of the ionized cluster beam, ICB, deposited Ag/n-Si(111) and Ag/p-Si(100) Schottky barrier junctions, for non zero Ag ions acceleration voltage U-a > 0 V, have been investigated. The effective Schottky barrier height (SBH) is observed to decrease if Ag is deposited on n-doped Si substrate but for Ag/p-Si junction shows an increase, relatively to the corresponding SBH values of U-a = 0 V ICB deposited junctions, respectively. The accelerated Ag metal ions, an essential characteristic of the ICE deposition method may for an appropriate value of U-a penetrate the Si wafer a few nm in depth and consequently might strongly contribute to an additional doping density within this-Ag enriched-Si region. For the penetration length L of the order of a few Si lattice lengths the penetrating energetic Ag ions are producing, before embedded within the substrate, some lattice structural damages what effectively results in the fact, that the Ag enriched silicon region may approximately be considered as the specific case of the disordered interface control layer, ICL. The modification of the Ag/Si energy bands due to the existence of this ICL in conjunction with the assumed DIGS electron charge density, occurring in the presumably abrupt plane between the Ag enriched region and the rest of the bulk Si substrate, has been calculated. On the basis of the obtained results, a tentative suggestion is advanced according to which the semiconductor local energy band modification (occurring as the simultaneous result of activated Ag deep impurity levels in the Si wafer and the appearance of localized charges due to DIGS) is to largest degree responsible for an effective unpinning of the semiconductor Fermi level inducing, in such a way, the modulation of the Schottky barrier height. (C) 1998 Elsevier Science Ltd. All rights reserved.