Probing the Atomic-Scale Structure of Amorphous Aluminum Oxide Grown by Atomic Layer Deposition.

Atomic layer deposition (ALD) is a well-established technique for depositing nanoscale coatings with pristine control of film thickness and composition. The trimethylaluminum (TMA) and water (HO) ALD chemistry is inarguably the most widely used and yet to date, we have little information about the atomic-scale structure of the amorphous aluminum oxide (AlO) formed by this chemistry. This lack of understanding hinders our ability to establish process-structure-property relationships and ultimately limits technological advancements employing AlO made ALD.

In Situ Thermal Atomic Layer Etching for Sub-5 nm InGaAs Multigate MOSFETs.

Thermal atomic layer etching (ALE) was demonstrated on ternary III-V compound semiconductors. In particular, thermal ALE on InGaAs and InAlAs was achieved with sequential, self-limiting fluorination and ligand-exchange reactions using hydrogen fluoride (HF) as the fluorination reactant and dimethylaluminum chloride (DMAC) as the ligand-exchange reactant. Thermal ALE was investigated on planar surfaces and three-dimensional nanostructures.

Electron-Enhanced Atomic Layer Deposition of Boron Nitride Thin Films at Room Temperature and 100 °C.

Electron-enhanced atomic layer deposition (EE-ALD) was used to deposit boron nitride (BN) thin films at room temperature and 100 °C using sequential exposures of borazine (BNH) and electrons. Electron-stimulated desorption (ESD) of hydrogen surface species and the corresponding creation of reactive dangling bonds are believed to facilitate borazine adsorption and reduce the temperature required for BN film deposition. In situ ellipsometry measurements showed that the BN film thickness increased linearly versus the number of EE-ALD cycles at room temperature.

Rapid Growth of Crystalline Mn5O8 by Self-Limited Multilayer Deposition using Mn(EtCp)2 and O3.

This work investigates the use of ozone as a post-treatment of ALD-grown MnO and as a coreactant with bis(ethylcyclopentadienyl)manganese (Mn(EtCp)2) in ALD-like film growth. In situ quartz crystal microbalance measurements are used to monitor the mass changes during growth, which are coupled with ex situ materials characterization following deposition to evaluate the resulting film composition and structure. We determined that during O3 post-treatment of ALD-grown MnO, O3 oxidizes the near-surface region corresponding to a conversion of 22 Å of the MnO film to MnO2.

Electron Enhanced Growth of Crystalline Gallium Nitride Thin Films at Room Temperature and 100 °C Using Sequential Surface Reactions.

Low energy electrons may provide mechanisms to enhance thin film growth at low temperatures. As a proof of concept, this work demonstrated the deposition of gallium nitride (GaN) films over areas of ∼5 cm at room temperature and 100 °C using electrons with a low energy of 50 eV from an electron flood gun. The GaN films were deposited on Si(111) wafers using a cycle of reactions similar to the sequence employed for GaN atomic layer deposition (ALD).

Ultrathin oxide films by atomic layer deposition on graphene.

In this paper, a method is presented to create and characterize mechanically robust, free-standing, ultrathin, oxide films with controlled, nanometer-scale thickness using atomic layer deposition (ALD) on graphene. Aluminum oxide films were deposited onto suspended graphene membranes using ALD. Subsequent etching of the graphene left pure aluminum oxide films only a few atoms in thickness.

Molecular layer deposition of aluminum alkoxide polymer films using trimethylaluminum and glycidol.

Molecular layer deposition (MLD) of aluminum alkoxide polymer films was examined using trimethlyaluminum (TMA) and glycidol (GLY) as the reactants. Glycidol is a high vapor pressure heterobifunctional reactant with both hydroxyl and epoxy chemical functionalites. These two different functionalities help avoid "double reactions" that are common with homobifuctional reactants.

Using atomic layer deposition to hinder solvent decomposition in lithium ion batteries: first-principles modeling and experimental studies.

Passivating lithium ion (Li) battery electrode surfaces to prevent electrolyte decomposition is critical for battery operations. Recent work on conformal atomic layer deposition (ALD) coating of anodes and cathodes has shown significant technological promise. ALD further provides well-characterized model platforms for understanding electrolyte decomposition initiated by electron tunneling through a passivating layer.

Ultrathin coatings on nano-LiCoO2 for Li-ion vehicular applications.

To deploy Li-ion batteries in next-generation vehicles, it is essential to develop electrodes with durability, high energy density, and high power. Here we report a breakthrough in controlled full-electrode nanoscale coatings that enables nanosized materials to cycle with durable high energy and remarkable rate performance. The nanoparticle electrodes are coated with Al(2)O(3) using atomic layer deposition (ALD).

Conformal surface coatings to enable high volume expansion Li-ion anode materials.

An alumina surface coating is demonstrated to improve electrochemical performance of MoO(3) nanoparticles as high capacity/high-volume expansion anodes for Li-ion batteries. Thin, conformal surface coatings were grown using atomic layer deposition (ALD) that relies on self-limiting surface reactions. ALD coatings were tested on both individual nanoparticles and prefabricated electrodes containing conductive additive and binder.

Atomic layer deposition on gram quantities of multi-walled carbon nanotubes.

Atomic layer deposition (ALD) was employed to grow coaxial thin films of Al(2)O(3) and Al(2)O(3) /W bilayers on multi-walled carbon nanotubes (MWCNTs). Although the MWCNTs have an extremely high surface area, a rotary ALD reactor was successfully employed to perform ALD on gram quantities of MWCNTs. The uncoated and ALD-coated MWCNTs were characterized with transmission electron microscopy and x-ray photoelectron spectroscopy.

Quantum confinement in amorphous TiO(2) films studied via atomic layer deposition.

Despite the significant recent increase in quantum-based optoelectronics device research, few deposition techniques can reliably create the required functional nanoscale systems. Atomic layer deposition (ALD) was used here to study the quantum effects attainable through the use of this ångström-level controlled growth process. Size-dependent quantum confinement has been demonstrated using TiO(2) layers of nanoscale thickness applied to the surfaces of silicon wafers.