Simple patterning via adhesion between a buffered-oxide etchant-treated PDMS stamp and a SiO₂ substrate

A very simple polydimethylsiloxane (PDMS) pattern-transfer method is devised, called buffered-oxide etchant (BOE) printing. The mechanism of pattern transfer is investigated, by considering the strong adhesion between the BOE-treated PDMS and the SiO₂ substrate. PDMS patterns from a few micrometers to sub-micrometer size are transferred to the SiO₂ substrate by just pressing a stamp that has been immersed in BOE solution for a few minutes. The patterned PDMS layers work as perfect physical and chemical passivation layers in the fabrication of metal electrodes and V ₂O₅ nanowire channels, respectively. Interestingly, a second stamping of the BOE-treated PDMS on the SiO₂ substrate pre-patterned with metal as well as PDMS results in a selective transfer of the PDMS patterns only to the bare SiO₂. In this way, the fabrication of a device structure consisting of two Au electrodes and V₂O ₅ nanowire network channels is possible; non-ohmic semiconducting I-V characteristics, which can be modeled by serially connected percolation, are observed.