[show abstract][hide abstract] ABSTRACT: At room-temperature ambient, carbon nanotubes (CNTs) were selectively synthesized on each bridge of the microheater array (MHA) formed on a glass substrate. Both multiwalled (MW) and single-walled CNTs could be formed by controlling the MHA temperature, which was confirmed from Raman spectroscopy. By incorporating the selectively grown MW CNTs into the lateral-gated field-emitter arrays, high current density of electron emission was observed with low device leakage.
IEEE Electron Device Letters 08/2009; · 2.79 Impact Factor
[show abstract][hide abstract] ABSTRACT: The photolithography process has generally been used for the making of catalyst layers used for the synthesis of CNTs due to its comparative ease. However, this method results in the formation of undesirable catalyst particles, which deteriorate the quality of the devices. Therefore, we tried to form a catalyst layer without using any lift-off or wet etching process, especially for the formation of carbon nanotube interconnects. After spin coating the samples, which were previously fabricated with several vias, with an iron-acetate solution, the catalyst layer was pulled down into the bottom of the holes through the force of gravity. We were able to remove the catalyst layer which was coated over undesirable areas, by TMAH (tetramethylammonium hydroxide, N(CH3)4OH) treatment. After the catalyst deposition process, we synthesized CNTs and observed them by scanning electron microscopy (SEM).
Thin Solid Films 01/2008; 516(11):3534-3537. · 1.60 Impact Factor
[show abstract][hide abstract] ABSTRACT: We studied the growth characteristics of carbon nanotubes which were grown from the uniformly dispersed iron nanoparticles prepared from iron acetate [Fe(II)(CH3COO)2]. The density of CNT was controlled from precursor concentrations. We also investigated the field emission properties of CNTs. We found that the optimization of CNT density is an important factor for field emission properties. Patterning process of iron acetate was achieved simply by alkaline solution.
Diamond and Related Materials - DIAM RELAT MATER. 01/2005; 14(3):810-814.
[show abstract][hide abstract] ABSTRACT: For field emitters as a cathode of traveling wave tube–microwave power amplifiers (TWT–MPA), field-emission (FE) properties of in situ grown carbon nanotubes (CNTs) onto electrically conducting substrate were systematically characterized. CNTs grown on the Co/TiN coated Ta substrate with properly controlled process exhibited the best FE property. The maximum current density and corresponding total emission current were 3.5 mA/cm2 and ∼1.7 mA at 21.6 V/μm, respectively. Details on the correlation between the FE properties and the morphological parameters will be discussed.
Diamond and Related Materials. 01/2004; 13:987-993.
[show abstract][hide abstract] ABSTRACT: A custom designed optical system is reported for tissue spectroscopy over four wavelengths of 677 nm, 780 nm, 830 nm, and 977 nm. A high speed laser driver is designed with a flat frequency response using pre-emphasis circuit. The driver is employed for high current in high power lasers. Phantom and intra-lipid experiments are performed to extract optical parameters of a turbid media. Broadband measurement is used to extract optical parameters of the phantom model simulating a breast tissue using forward scattering models. The optical parameters () are extracted with a very good accuracy.
[show abstract][hide abstract] ABSTRACT: In this paper, we report a systematic study on the field emission properties of CNTs depending on various catalyst metals (such as Ni, Co) and buffer layers (such as Cr, Mo, and TiN), which provide high conductivity, for high field-emission current.
Vacuum Microelectronics Conference, 2003. Technical Digest of the 16th International; 08/2003