Optical Properties of Nanostructured Sol–Gel Thin Films Doped with Fe<SUB>2</SUB>O<SUB>3</SUB> and Their Ferromagnetic Characterization by Mössbauer Spectroscopy

Abstract

Individual single-walled carbon nanotubes (SWCNTs) were synthesized on the patterned water-soluble catalyst by thermal chemical vapor deposition. The individual SWCNTs were obtained by introducing polyvinylpyrrolidone (PVP) as a dispersant. The number of SWCNTs between two electrodes were approximately 1-2 with an average diameter of about 1.7 nm and a yield of forming electrodes of nearly 70%. The PVP played an important role in dispersing catalysts and suppressing the active sites to limit the number of SWCNTs during synthesis, which is a critical condition for fabrication of field effect transistors (FETs). The measured I-V characteristics of the over layer-deposited electrodes revealed a clear gating effect in large portion, in good agreement with Raman observations in several excitation energies. The patterning procedure, catalyst preparation, and growth condition for fabrication of the SWCNT-FET were further discussed.

Photoluminescence Studies on ZnO Thin Films Obtained by Sol-Gel Method

“…The monolith undergoes gelation, aging, and drying to form the final xerogel. Films can be made by either spin coating [5] or dip coating [6] the sol onto a substrate, see Figure 2. Spin coating is a technique used since the 90s used to deposit thin films on different types of flat substrates.…”

“…Crystalline films are obtained by calcination process between 450 and 550°C to produce ZnO nanocrystals into the films [7]. [5] and (b) dip-coater device [6], both used to deposit sol-gel thin films on to silicon or glass substrates.…”

Optical Characterization of NiO Doped Fe₂O₃

“…Many researchers have worked on different techniques for fabricating Fe 2 O 3 such as; Spray pyrolytic method [9][10], Sol-gel [11][12], spin-coating deposition [13], chemical vapor deposition [14], sputtering [15] and DC reactive magnetron sputtering [16], and pulsed laser deposition [17]. …”