Dispersive resonance bands within the space charge layer of metal- semiconductor junction

TL;DR

This study reveals a fourth dispersive band within the space charge layer of a Pb/Ge(111) metal-semiconductor junction, showing its localized nature and implications for electronic device design.

Contribution

It identifies a new dispersive band near the surface zone center and demonstrates its localized nature within the space charge layer through combined experimental and theoretical analysis.

Findings

Discovery of a fourth dispersive band near the surface zone center.

The dispersive band weakens and disappears with increased Pb thickness.

The band is localized within the space charge layer, confirmed by ab initio calculations.

Abstract

Based on measurements of angle resolved photoemission, we report that in the Pb/Ge(111)- \sqrt{3}x\sqrt{3} R30^\circ structure, in addition to three bands resembling Ge heavy hole (HH), light hole (LH), and split off (SO) bulk band edges, a fourth dispersive band resembling the non split off (NSO) band is found near the surface zone center. While three Ge bulk-like bands get distorted due to strong coupling between Pb and Ge, the NSO-like band gets weaker and disappears for larger thickness of Pb, which, when combined with ab initio calculations, indicates its localized nature within space charge layer. Our results are clearly important for designing electronics involved with metal-semiconductor contacts.