Soojin Oh

Liquid-phase fabrication of patterned carbon nanotube field emission cathodes

High-resolution electron field emission cathodes were fabricated at room temperature by a high throughput electrophoresis process using functionalized carbon nanotubes (CNTs). Well-defined and adherent CNT patterns with 20 μm feature size were achieved on a variety of substrates with fine control of the CNT morphology. The cathodes show uniform emission pattern across the entire surfaces and emission current with long-term stability. This room-temperature liquid-phase process is efficient and has no intrinsic limit on the deposition area. The emission characteristics of these cathodes compare favorably to those from other fabrication methods for CNT based field emission display applications.

Room-temperature fabrication of high-resolution carbon nanotube field-emission cathodes by self-assembly

In this letter, we report a process for room-temperature assembly of patterned and periodic structures of carbon nanotubes (CNTs). Well-defined patterns with less than a 10-μm linewidth and variable thickness were readily deposited. The CNTs show long-range in-plane orientation ordering and adhere strongly to the substrates. The self-assembled macroscopic structures emit electrons under applied electrical field with the emission characteristics comparable to those from the high-temperature or/and low-resolution deposition processes. This room-temperature self-assembly method can be utilized for assembly and integration of nanostructured materials for a variety of devices, including the field-emission displays.

Near-edge absorption fine structure and UV photoemission spectroscopy studies of aligned single-walled carbon nanotubes on Si(100) substrates

We report near-edge absorption fine structure (NEXAFS) and UV photoemission spectroscopy (UPS) studies of aligned single-walled carbon nanotube films on Si(100) substrates. Orientation of the films was detected in the NEXAFS spectra, with the intensity of the π* core exciton at 284.4 eV showing a strong dependence on nanotube alignment with respect to the polarization of the incident radiation. At lower angles of incidence, the intensity of the π* peak was higher for all orientations, which we attribute to the greater accessibility of the π* orbitals. UPS spectra of the films showed little angular dependence and included features consistent with the total density of states of graphite. As a result of the nanotube curvature and the distribution of nanotube chiralities, the UPS spectra are similar to angle-integrated graphite spectra.

Room‐Temperature Fabrication of High‐Resolution Carbon Nanotube Field‐Emission Cathodes by Self‐Assembly

We report a process to assemble carbon nanotubes (CNTs) into patterned and periodic structures by self‐assembly at room temperature. Patterns of 10 μm or smaller can be readily deposited on various types of substrates using functionalized CNTs. The self‐assembled CNTs have in‐plane orientational order, and adhere strongly to the substrates. Under applied electric field they emit electrons with emission characteristics comparable to the CNT cathodes made by other techniques. This room temperature process can be utilized for assembly and integration of nano‐structured materials for a variety of devices including field emission displays.