title: Electrically biased nanolithography with KOH-coated AFM tips.
abstract: This letter provides the first study aimed at characterizing the desorption and nanolithographic processes for SAM-coated, gold-coated silicon substrates oxidatively patterned with an AFM with a tip under potential control. The process either results in recessed patterns where the monolayer has been removed or raised structures where the monolayer has been removed and silicon oxidation has taken place. Eleven different SAMs have been studied, and the type of pattern formed depends markedly upon SAM chain length, end functional group, and applied bias. We show how local pH and choice of monolayer can be used to very effectively control the type of pattern that is ultimately formed. Interestingly, we show that hydroxide anion accessibility to the substrate surface is one of the most significant factors in determining the pattern topography. Moreover, control over the pattern topography can be achieved by controlling the concentration of the KOH in the water meniscus formed at the point of contact between tip and surface in the context of a bias-controlled DPN experiment with a KOH-coated tip. The work provides important insight into the factors that control SAM desorption and also ways of controlling the topography of features made in a potential-controlled scanning probe nanolithographic process.
authors: Department of Chemistry and International Institute for Nanotechnology, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, USA.
authors: Jae-Won
authors: JW
authors: Jang
authors: Raymond G
authors: RG
authors: Sanedrin
authors: Daniel
authors: D
authors: Maspoch
authors: Seongpil
authors: S
authors: Hwang
authors: Tsuyohiko
authors: T
authors: Fujigaya
authors: You-Moon
authors: YM
authors: Jeon
authors: Rafael A
authors: RA
authors: Vega
authors: Xiaodong
authors: X
authors: Chen
authors: Chad A
authors: CA
authors: Mirkin
mesh_terms: D004574:Electromagnetic Fields; D004595:Electroplating / Q000379:methods*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006878:Hydroxides / Q000737:chemistry*; D018625:Microscopy, Atomic Force / Q000295:instrumentation* / Q000379:methods; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure; D036103:Nanotechnology / Q000295:instrumentation* / Q000379:methods; D017680:Potassium Compounds / Q000737:chemistry*; D014159:Transducers
chemical_list: D006878:Hydroxides; D017680:Potassium Compounds; C029943:potassium hydroxide