Radical-triggered cross-linking for molecular layer deposition of SiAlCOH hybrid thin films.

Here, we report on a simultaneous growth and radical-initiated cross-linking of a hybrid thin film in a layer-by-layer manner via molecular layer deposition (MLD). The cross-linked film exhibited a self-limiting MLD growth behavior and improved properties like 12% higher film density and enhanced stability compared to the non-cross-linked film.

Molecular layer deposition of hybrid siloxane thin films by ring opening of cyclic trisiloxane (V3D3) and azasilane.

In this work, we report the first ring opening vapor to solid polymerization of cyclotrisiloxane and N-methyl-aza-2,2,4-trimethylsilacyclopentane by molecular layer deposition (MLD). This process was studied in situ with a quartz crystal microbalance and the thin film was characterized by X-ray photoelectron spectroscopy, ATR-FTIR and high-resolution transmission electron microscopy.

Three-dimensional Ni/TiO2 nanowire network for high areal capacity lithium ion microbattery applications.

The areal capacity of nanowire-based microbatteries can be potentially increased by increasing the length of nanowires. However, agglomeration of high aspect ratio nanowire arrays could greatly degrade the performance of nanowires for lithium ion (Li-ion) battery applications. In this work, a three-dimensional (3-D) Ni/TiO(2) nanowire network was successfully fabricated using a 3-D porous anodic alumina (PAA) template-assisted electrodeposition of Ni followed by TiO(2) coating using atomic layer deposition. Compared to the straight Ni/TiO(2) nanowire arrays fabricated using conventional PAA templates, the 3-D Ni/TiO(2) nanowire network shows higher areal discharging capacity. The areal capacity increases proportionally with the length of nanowires. With a stable Ni/TiO(2) nanowire network structure, 100% capacity is retained after 600 cycles. This work paves the way to build reliable 3-D nanostructured electrodes for high areal capacity microbatteries.

Metalcones: hybrid organic-inorganic films fabricated using atomic and molecular layer deposition techniques.

Hybrid organic-inorganic films can be deposited using atomic layer deposition (ALD) and molecular layer deposition (MLD) techniques. A special set of hybrid organic-inorganic films based on metal precursors and various organic alcohols yields metal alkoxide films that can be described as "metalcones." Many metalcone films are possible such as the "alucones" and "zincones" based on the reaction of trimethylaluminum and diethylzinc, respectively, with various organic alcohols such as ethylene glycol (EG). This paper reviews the previous work on metalcone MLD and discusses a variety of new metalcone systems. "Titanicones" are grown using TiCl4 and glycerol or EG and "zircones" are grown using zirconium tetra-tert-butoxide and EG. In addition, the organic alcohol can also be varied to change the properties within one metalcone family. For example, the glycerol triol precursor allows for more cross-linking and higher toughness in alucones than the EG diol precursor. Alloys can also be formed by combining metalcone MLD and metal oxide ALD. By varying the relative number of cycles of MLD and ALD, the composition and properties of the hybrid organic-inorganic films can be tuned from pure metalcone MLD to pure metal oxide ALD.

Protecting polymers in space with atomic layer deposition coatings.

Polymers in space may be subjected to a barrage of incident atoms, photons, and/or ions. Atomic layer deposition (ALD) techniques can produce films that mitigate many of the current challenges for space polymers. We have studied the efficacy of various ALD coatings to protect Kapton polyimide, FEP Teflon, and poly(methyl methacrylate) films from atomic-oxygen and vacuum ultraviolet (VUV) attack. Atomic-oxygen and VUV studies were conducted with the use of a laser-detonation source for hyperthermal O atoms and a D2 lamp as a source of VUV light. These studies used a quartz crystal microbalance (QCM) to monitor mass loss in situ, as well as surface profilometry and scanning electron microscopy to study the surface recession and morphology changes ex situ. Al2O3 ALD coatings protected the underlying substrates from atomic-oxygen attack, and the addition of TiO2 coatings protected the substrates from VUV-induced damage. The results indicate that ALD coatings can simultaneously protect polymers from oxygen-atom erosion and VUV radiation damage.