Electrical properties of amino SAM layers studied with conductive AFM

Self assembled monolayers derived from amino silane precursors (C11 NH2) are studied using conductive AFM (C-AFM) technique in high vacuum (HV) conditions (∼5 × 10−5 torr). Working in HV condition was preferred to working in air in order to reduce the impact of water meniscus on the surface which increases the adhesion forces causing smearing of the SAMs. C-AFM current maps of these samples indicate a decrease in the number of leakage spots with an increase in the deposition time. The latter is indicative of a trend towards a complete coverage of SAMs for the higher deposition times. To further assess the electrical properties of the SAMs, point I–V spectroscopy measurements were performed up to the point of electrical breakdown. The breakdown voltage increases with the increase in the number of multilayers for the 3 h, 6 h, and 18 h deposition time and then drops for the 24 h deposition time. In this final case we speculate that the numbers of impurity sites are higher and the charge carriers need less electric field to tunnel to the nearest site.