INFLUENCE OF THIN METALLIC INTERLAYERS ON THE CDS/INP(110) VALENCE BAND OFFSET

The experimental determination of valence band offsets in semiconductor heterojunctions often disagrees with theoretical predictions. This deviation is attributed to reacted interlayers at the interface, which induce additional dipoles and thus tune the valence band offset. Therefore we have studied the influence of ultrathin metal interlayers with different reactivity and found indeed that these layers change the valence band offset. We have characterized the CdS/InP(110) heterojunction with monolayers of Sb and Bi (unreactive) and Al (reactive) using core and valence level photoemission. These metals were chosen since their interaction with InP had been extensively studied before. We find that the Sb and Bi interlayers decrease the valence band offset by 0.2 eV, while Al leads to an increase of about 0.1 eV. The interlayers are also found to have a significant influence on the amount of interface reaction.