Dramatically improved yields in molecular scale electronic devices using ultra-smooth platinum electrodes prepared by chemical mechanical polishing

We report a dramatic improvement in the yields of molecular scale electronic devices by using ultra-smooth platinum (Pt) electrodes made with chemical mechanically polishing (CMP). A large number of measurements were carried out in order to investigate the surface roughness of freshly deposited Pt films using atomic force microscopy (AFM) and a root-mean square (RMS) roughness of 7Å was observed. We developed and applied a CMP process to achieve ultra-smooth Pt surfaces with less than 1Å RMS roughness and grew two different types of molecular monolayers, i.e. SAMs of alkoxynaphthalene thiols and Langmuir-Blodgett (LB) monolayers of eicosanoic acid on polished Pt electrodes defined by optical lithography. Using AFM, contact angle measurements and ellipsometry, we observed a dramatic improvement in the packing and orientation of both types of monolayer. An impressive 100% device yield in the molecular devices made of LB monolayer and ∼35% yields in the devices made with SAM monolayer of alkoxynaphthalene thiols molecules with device sizes varying from 1μm×5μm to as big as 20μm×5μm were observed.