Characterization of Nanoparticles Fabricated by Oxidation of Ni80Fe20 and Co80Fe20 Thin Films during Imidization

Effect of Curing Conditions on the Fabrication of Zn-oxide Nanoparticles Dispersed in a Polyimide Film

Zinc oxide nanoparticles were formed by reacting polyamic acid (PAA) with Zn during curing. In this paper, we investigated the effect of curing conditions on the zinc oxide nanoparticle formation. The polyimide (PI) precursors used in this study were biphenyltetracarboxylic dianhydride- p-phenylene diamine (BPDA-PDA) type and oxydiphthalic dianhydride 3-sulful dianhydride (ODPA-3SDA) type PAAs. Zn thin films were deposited on silicon substrates by DC magnetron sputter. PAA was then spin-coated onto Zn thin films and the PAA/metal films were cured at various conditions. The characterization using transmission electron microscope observation was carried out to investigate the size and distribution of zinc oxide particles. Zinc oxide nanoparticles were formed in the PI film regardless of the curing conditions. The size, distribution and density of zinc oxide particles were strongly dependent on the curing conditions..

The growth mechanism for silicon oxide nanowires synthesized from an Au nanoparticle/polyimide/Si thin film stack

During pyrolysis of polyimide (PI) thin film, amorphous silicon oxide nanowires (SiO(x)NWs) were produced on a large scale through heat treatment of an Au nanoparticle/PI/Si thin film stack at 1000 °C. It was shown that carbonization of the PI film preceded the nucleation of the SiO(x)NWs. The formation of the SiO(x)NWs was sustained by the oxygen derived from carbonization of the polyimide thin film while Si was provided from the substrate. Au nanoparticles promoted the SiO(x)NW growth by inducing localized melting of the Si substrate and by catalyzing the nanowire growth.

Co–Pt alloy nanoparticles produced using a template of nanoparticle array

A monolayer of Co-Pt alloy nanoparticles in the nanometer-size regime was fabricated using a nanotemplate approach. 1.7-nm-thick Co46Pt54 film was deposited onto a preexisting array of Ni seed particles embedded in a polyimide film. During subsequent annealing, the deposited Co46Pt54 film coalesced onto the seed particles to produce a monolayer of Co-Pt alloy particles. Deposition and annealing were repeated to increase both average particle size and volume fraction of the alloy particles. It was also shown that the annealing temperature was critical in controlling the particle size distribution and the final composition of the nanoparticles. This method of forming a single layer of vertically aligned nanoparticles can be easily extended to a large area as well as to produce a different combination of alloy particles on a polymer film.

Mono-layer of Ni(100-x)Fe(x) nanoparticles fabricated on a polyimide film under different curing atmospheres

A mono-layer of nano-sized metal particles was prepared on the surface of a polyimide film by simply depositing a thin film of Ni80Fe20 on top of the polyamic acid that was spin coated onto a Si wafer. During thermal imidization of the polyamic acid film, Fe was selectively etched by reacting with the carbonyl group of the polyamic acid to leave behind uniformly distributed Ni-rich metallic particles. The average diameter of the particles was 4 nm and the particles were confined into a single layer on top of the polymer film. Moreover, it was also shown that the morphology of the nanoparticles can be substantially altered by curing the precursor film in a hydrogen atmosphere, without significantly damaging the polymer film. Thus produced nanoparticles lay exposed on top of the electrically insulating and chemically stable polymer film so that it is possible that the nanoparticles can be directly used for fabricating a nonvolatile flash memory device or as a template for building functional nano-structures.