The BPD SAM fabricated as above was characterized using X-ray photoelectron spectroscopy (XPS). XPS spectroscopy measurements were conducted at the MANA Foundry using an XPS spectrometer (Alpha 110-mm analyzer XPS version; Thermo Fisher Scientific, Chiyoda-ku, Tokyo, Japan). The XPS spectra were recorded in the Au 4f, S 2p, C 1 s, N 1 s, and Ni 2p regions. Spectrum acquisition was done in normal emission geometry using the Al K radiation. The binding energy (BE) scale Selleckchem 17DMAG of each spectrum was calibrated individually to the Au 4f

7/2 emission of an n-alkanethiol-covered gold substrate at 83.95 eV. In addition, XPS data were used to ascertain the effective thickness of the target SAMs. This assessment was done based on the Au 4f intensity, assuming standard exponential attenuation of the photoelectron signal and using the attenuation lengths described in an selleck inhibitor earlier report [12]. The exposure of BPD-Ni film to electron beams engenders the formation of crosslinked SAMs. As shown in Figure 2c, the

BPD-Ni template was patterned by electrons (50 kV, 60 mC/cm2) in proximity printing geometry using a metal TEM mesh as a mask. The patterned template was etched in an I2/KI-etch bath. As Figure 2c shows, the optical microscope image depicts the underlying gold substrate within the irradiation areas unaffected by the etching process as evidence that the crosslinked mechanism take place in the BPD-Ni SAM after radiation, although it was etched

within the non-irradiated region. Fabrication of the top electrode Pre-patterning resist for the top contact was accomplished similar to the fabrication of the bottom electrode. First, PMMA 950 was spin-coated at 2,000 rpm for 90 s and baked at 180°C for 3 min. Then ESPACER 300Z™ (Showa Denko K.K.) was spin-coated on top of the PMMA at 2,000 rpm for 60 s. The 100-nm bar patterns perpendicularly aligned with respect Uroporphyrinogen III synthase to the bottom electrodes were fabricated using the electron beam lithography (50 kV, 100 mC/cm2). Then the resist was developed in the MIBK-IPA solution for 30 to 40 s to form the pattern for the top electrode lines. Finally, 10 nm of titanium and 150 nm of gold were deposited by electron-beam evaporation on the photoresist-patterned wafer. The wafer was immersed in acetone to remove the photoresist and the excess metal which adhered on the resist (Figure 1e). Figure 3 depicts SEM images of the crossbar devices. Figure 3 SEM images of the crossbar device. (a) General view of the two devices. (b) Red structure shows the bottom electrodes. (c) High-magnification images of the crossbar device to show the bottom and the top electrodes. Characterization of crossbar devices Temperature-dependent I-V characteristics of the molecular devices were acquired using a standard semiconductor parameter analyzer (HP 4145 B; Agilent Technologies, Sta.