Effective Metal Top Contact on the Organic Layer via Buffer-Layer-Assisted Growth: A Multiscale Characterization of Au/Hexadecanethiol/n-GaAs(100) Junctions

International audienceIn the field of organic and molecular electronics at monolayer coverage, the need for abrupt and well-controlled top metal contacts is a key point. A general method which provides reliable molecular junctions with most metals remains to be found. In this paper we show that reliable molecular junctions Au/hexadecanethiol/n-GaAs(100) are obtained using buffer-layer-assisted growth (BLAG). They show in hot electron transport measurements at the nanoscale a tunnel regime through the organic monolayer with a full spatial uniformity. Using ballistic electron emission microscopy (BEEM) in the spectroscopic mode as well as photoemission and C(V)-transport measurements, we draw a coherent band alignment scheme of the whole heterostructure at the nanoscale and at the macroscopic scale. Through this study, the BLAG method appears as a general method that should work for contacting organic monolayers with most metals. © 2016 American Chemical Society