Chemical bonding and nanomolecular length effects on work function at Au-organophosphonate-HfO_2 interfaces

摘要

We demonstrate that introducing a thiol-terminated organophosphonate nanomolecular layer (NML) can increase the effective work function at Au-HfO_2 interfaces by up to ΔΦ_(eff) = 0.55 ± 0.05 eV. Capacitance measurements of Au-NML-HfO_2-SiO_2-Si stacks and ultraviolet photoelectron spectroscopy of Au-NML-HfO_2 structures, and parts thereof, reveal that Φ_(eff) shifts are primarily determined by the length of the molecules comprising the NML, while Au-NML and NML-oxide bonding dipole contributions tend to counteract each other. Our findings provide insights into tailoring the electronic properties of metal-oxide heterointerfaces for applications by harmonizing the effects of interracial bonding and NML morphology.