ABSTRACT
Atomic layer deposition (ALD) was used to prepare amorphous thin films of Al2O3, Nb2O5, and Ta2O5 on both silicon substrates and aluminum blocks. Etch rates in 10 M NH4OH were determined from X-ray reflectometry data collected as a function of time. Amorphous Al2O3 thin films were found to have an etch rate of 0.5 nm min-1 and an increase in roughness of â¼0.01 nm min-1. Electron microscopy data showed etch pits, consistent with the increase in roughness. Amorphous Nb2O5 and Ta2O5 films showed no appreciable etching or roughening over the course of a â¼500 h continuous immersion. An Nb2O5-coated aluminum block showed no corrosion after immersion in 10 M NH4OH for over 200 h, suggesting that the coatings were pinhole-free. These results suggest that amorphous ALD thin films of Nb2O5 and Ta2O5 are candidates as barrier layers for aluminum in caustic environments.
ABSTRACT
We report a simple and rapid method to prepare multifunctional free-standing single-walled carbon nanotube (SWCNT) films with variable thicknesses ranging from a submonolayer to a few micrometers having outstanding properties for a broad range of exceptionally performing devices. We have fabricated state-of-the-art key components from the same single component multifunctional SWCNT material for several high-impact application areas: high efficiency nanoparticle filters with a figure of merit of 147 Pa(-1), transparent and conductive electrodes with a sheet resistance of 84 Ω/â» and a transmittance of 90%, electrochemical sensors with extremely low detection limits below 100 nM, and polymer-free saturable absorbers for ultrafast femtosecond lasers. Furthermore, the films are demonstrated as the main components in gas flowmeters, gas heaters, and transparent thermoacoustic loudspeakers.
ABSTRACT
We demonstrate an aerosol CVD process to dry deposit large-area SWCNT networks with tunable conductivity and optical transmittance on a wide range of substrates including flexible polymers. These SWCNT networks can be chemically doped to reach a sheet resistance of as low as 110 Ω/⟨ at 90% optical transmittance. A wide application potential of these networks is demonstrated by fabricating SWCNT network-based devices such as a transparent capacitive touch sensors, thin-film transistors (TFTs), and bright organic light-emitting diodes (OLEDs).
Subject(s)
Aerosols/chemistry , Crystallization/methods , Nanotechnology/methods , Nanotubes, Carbon/chemistry , Nanotubes, Carbon/ultrastructure , Electric Conductivity , Macromolecular Substances/chemistry , Materials Testing , Molecular Conformation , Particle Size , Surface PropertiesABSTRACT
Mode-locked sub-picosecond operation of Yb-, Er- and Tm:Hodoped fiber lasers operating at 1.05 microm, 1.56 microm and 1.99 microm, respectively, is demonstrated using the same sample carbon nanotube-based saturable absorber mirror. A mesh of single-walled carbon nanotubes was deposited on an Ag-mirror using a one-step dry-transfer contact press method to combine broadband saturable absorption and high reflectance properties. The novel fabrication method of the polymer-free absorber and device parameters determined using nonlinear reflectivity measurement are described in detail. To our knowledge the observed operation bandwidth of approximately 1 microm is the broadest reported to date for a single carbon nanotube-based saturable absorber.
