Molecular length effect on work function shifts at copper-organophosphonate-hafnia interfaces

Abstract

We demonstrate that inserting a mercaptan-terminated organophosphonic acid monolayer at a Cu-HfO2 interface can alter the metal work function by −0.1 eV ≤ΔΦ≤−0.4 eV. The electron spectroscopy measurements of valence band structure reveal that molecular length-induced changes in ΔΦ can exceed contributions from Cu-S and P-O-Hf bonding dipoles at the Cu-organophosphonate-HfO2 interfaces. The invariance of the organophosphonate monolayer thickness with molecular length indicates that the observed values of ΔΦ are due to differences in molecular configuration and monolayer morphology. These findings suggest that molecular length could be a knob for tuning the electronic properties of inorganic interfaces modified with a nanomolecular layer for applications.

Large Increase in the Dielectric Constant and Partial Loss of Coherence Increases Tunneling Rates across Molecular Wires

“…This d mol -dependent increase in Δ U SAM also results in an increase of the δ E H values from 2.9 to 3.2 eV for Au–Cys­(Gly) n ,gly and 2.7 to 3.4 eV for Au–S­(CH 2 CH 2 O) n ,eg CH 3 SAMs shown in Figure l. Similar shifts in energy level alignment have also been observed before for other systems. , …”

“…Similar shifts in energy level alignment have also been observed before for other systems. 50,51 J(V) Characterization. We measured the J(V) characteristics of the junctions with cone-shaped GaO x /EGaIn top contacts using previously reported methods.…”

Selective Pd recovery from acidic leachates by 3-mercaptopropylphosphonic acid grafted TiO2: does surface coverage correlate to performance?

“…S − or S 2− ), and can possibly be related to thiol groups looping back to the surface through interaction with the surface. 39 Despite the lower signal-to-noise ratio for 3MPPA20, the relative contribution of the S1 component on the total intensity of the S 2p spectrum seems to increase with increasing 3MPPA concentration.…”

“…The few studies available for graing with sulfur-based PAs are mainly oriented towards tuning the electronic properties in nanoelectronics devices [36][37][38][39][40] and the development of quantum dot sensitized solar cells. [41][42][43] Although PGMs have a strong affinity for sulfur functionalities in metal sorption, this research area has remained largely unexplored for organophosphonic acid modied metal oxides.…”