Single molecule magnet bridging along exposed sidewalls of metal insulator semiconductor diodes for molecularly...

Single Molecule Magnets (SMMs) are promising for molecular spintronics owing to their quantum properties; however, reproducible integration into devices has remained challenging due to limitations of break-junction and gold-based systems. This study introduces a scalable NiFe/AlOx/p-Si Metal Insulator Semiconductor (MIS) platform that enables sidewall integration of lipoic acid-functionalized Mn₆ SMMs in a configuration consistent with sulfur-based molecular anchoring at exposed junction edges. Despite fabrication-related variability in pristine MIS junctions, molecular integration produced more convergent reproducible tunneling characteristics across multiple devices, as confirmed by standard deviation analysis. Importantly, charge transport in this architecture remains fundamentally governed by tunneling across the MIS barrier. Molecular integration does not replace intrinsic MIS transport but is associated with modification of interfacial electrostatics, electrode work function, and effective tunneling barrier properties, resulting in improved reproducibility of measured tunneling characteristics across devices. Kelvin Probe Force Microscopy (KPFM) revealed an approximately 0.4 V increase in NiFe surface potential following SMM attachment, providing electrode-level evidence of interfacial electronic modification following molecular treatment. Conceptual modeling suggests two cooperative mechanisms: (i) molecule-induced modification of tunneling barrier electrostatics, quantitatively supported by Brinkman model analysis, and (ii) charge redistribution at the NiFe/SMM interface, which modifies electrode work function and electrostatic boundary conditions of the MIS junction. While direct spectroscopic identification of specific molecular orbitals such as the Lowest Unoccupied Molecular Orbital (LUMO) was not performed, the observed conductance enhancement, tunneling barrier modification, and surface potential shift strongly support molecule-induced modulation of the MIS tunneling barrier through interfacial electronic coupling and associated electrostatic barrier modulation. The present conclusions are limited to the specific case of lipoic acid-functionalized Mn₆ SMMs and should be interpreted as a system-specific demonstration rather than a universal statement for all molecularly modified MIS junctions.