Fabrication of quantum dots using multicoated self-assembled monolayer

Abstract

The authors have fabricated quantum dots with various nanogaps by controlling the number of self-assembled molecular coatings. First, Au electrodes with a unique shape were obtained using conventional lithography. Then, a self-assembled multilayer, composed of alternating layers of 16-mercaptoalkanoic acids [HS(CH(2))(15)COOH, 16-MHDA] and copper (II) ions, were deposited on Au electrode patterns to form the controllable gap between adjacent Au electrodes. After reaching a nanometer-scale gap, the second Au was deposited again using e-beam evaporation. Finally, both the second Au and molecular resist were removed by lift-off, thereby resulting in quantum dots with a nanogap between gold electrodes. Ellipsometry and cyclic voltammetry were used to find the number of self-assembled molecular layers. In addition, contact angle and x-ray photoelectron spectroscopy were used to analyze chemical properties between gold and the self-assembled multilayer. Field-emission scanning-electron microscopy was used for characterization of shapes of nanogaps and quantum dots. (C) 2010 American Vacuum Society. [DOI: 10.1116/1.3360923]