  For electronic and photoelectronic devices based on GeSe, an emergent two
dimensional monochalcogenide with many exciting properties predicted, good
electrical contacts are of great importance for achieving high device
performances and exploring the intrinsic physics of GeSe. In this article, we
use temperature-dependent transport measurements and thermionic emission theory
to systematic investigate the contact-barrier heights between GeSe and six
common electrode metals, Al, Ag, Ti, Au, Pt and Pd. These metals cover a wide
range of work functions (from ~ 3.6 eV to ~ 5.7 eV). Our study indicates that
Au forms the best contact to the valence band of GeSe, even though Au does not
possess the highest work function among the metals studied. This behavior
clearly deviates from the expectation of Schottky-Mott theory and indicates the
importance of the details at the interfaces between metals and GeSe.
