Nanoscale Probing of Surface Charges in Functional Copper‐Metal Organic Clusters by Kelvin Probe Force Microscopy for Field‐Effect Transistors

Abstract

AbstractMetal–organic frameworks (MOFs) have recently attracted a great deal of attention especially as conceivable advanced gate dielectrics for next‐generation field‐effect transistors (FETs) and memory device applications. Dielectric surface charge retention mapping is essential for gauging the leakage current and threshold voltage stability. Due to a dearth of systematic real‐time surface charge probing of MOFs dielectrics, in this work, the nanoscale Kelvin probe force microscopy (KPFM) technique is employed for the contact potential difference (CPD) analysis of developed hybrid copper–metal–organic clusters (Cu‐MOCs)/Si systems. Films are synthesized through the sol‐gel process consisting of copper metal core linked with organic ligands. With 3V positive and negative DC bias, charge injection offset between positive and negative bias is observed to be ≈190 mV, indicating the intrinsic Fermi level alignment between KPFM tip and sample surface charges. The high‐resolution surface CPD mappings bring forth the white (≈98 mV) and black (≈−91 mV) contrast profiles with hole (5.09 × 1012 cm−2) and electron (4.74 × 1012 cm−2) charge densities. Also, the 17 h time‐lapse enables the holes and electrons CPD mapping diameter shrinkage by ≈32% and 46%, respectively. In furtherance, a conductive filament model for host‐guest proton‐assisted conduction with charge hopping through fixed/mobile ions is proposed.