Atomic layer deposition

About: Atomic layer deposition is a research topic. Over the lifetime, 19821 publications have been published within this topic receiving 477332 citations. The topic is also known as: ALD.

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

Abstract: 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. First-principles calculations reveal two regimes of electron transfer to adsorbed ethylene carbonate molecules (EC, a main component of commercial electrolyte), depending on whether the electrode is alumina coated. On bare Li metal electrode surfaces, EC accepts electrons and decomposes within picoseconds. In contrast, constrained density functional theory calculations in an ultrahigh vacuum setting show that, with the oxide coating, e– tunneling to the adsorbed EC falls within the nonadiabatic regime. Here the molecular reorganization energy, computed in the harmonic approximation, plays a k...

Ferroelectricity in undoped-HfO2 thin films induced by deposition temperature control during atomic layer deposition

Abstract: HfO2 thin films, extensively studied as high-k gate dielectric layers in metal-oxide-semiconductor field effect transistors, have attracted interest of late due to their newly discovered ferroelectricity in doped HfO2. The appearance of the ferroelectric orthorhombic phase of HfO2 was previously examined in variously doped and undoped systems, but the effects of process-variable changes on the physical and chemical characteristics of a thin film and the resulting ferroelectricity have not been studied systematically. Here, the evolution of ferroelectricity in HfO2 thin films through deposition temperature control during atomic layer deposition was systematically examined without the intentional doping of metallic elements other than Hf. The lower-temperature-deposited HfO2 showed an increased impurity concentration, which was mainly carbon, and the involvement of these impurities suppressed the lateral grain growth during the crystallization thermal treatment. The grain size reduction could stabilize the metastable orthorhombic phase, whose surface and grain boundary energies are lower than those of the room-temperature-stable monoclinic phase, by increasing the grain boundary areas. The 9 nm-thick HfO2 thin film deposited at 220 °C exhibited a remanent polarization value of 10.4 μC cm−2 and endured up to 108 switching cycles, which is a 102-fold improvement compared to the previously reported undoped 6 nm-thick HfO2. This can be ascribed to the decrease in the relative portion of defective interfacial layers by increasing the total film thickness. The strategy of using deposition temperature control is a feasible method for the fabrication of these new lead-free binary ferroelectric thin films.

Photocatalysis of Ag-Loaded TiO2 Nanotube Arrays Formed by Atomic Layer Deposition

Abstract: Anodic aluminum oxide (AAO) film was used as a template to fabricate TiO2 nanotubes. TiO2 was deposited into the AAO pores by atomic layer deposition (ALD) at 100 °C. After the top layer of TiO2 and the AAO template were removed, an ordered array of TiO2 nanotubes remained on the substrate. The tube thickness increased with the cycle number of ALD. The UV–vis absorption spectra of the samples exhibited a red shift as the thickness increased or after annealing. The photocatalytic activity increased with the increase in the wall thickness of TiO2 nanotubes. With deposition of Ag nanoparticles on the tubes, the nanoparticles could act as an electron trapper to slow the electron–hole recombination rate, and thus enhance the efficiency of photodecomposition of methyl orange.

Method for energy-assisted atomic layer deposition and removal

Abstract: A method for energy-assisted atomic layer deposition and removal of a dielectric film are provided. In one embodiment a substrate (14) is placed into a reaction chamber (10) and a gaseous precursor is introduced into the reaction chamber (10). Energy is provide by a pulse of electromagnetic radiation which forms radical species of the gaseous precursor. The radical species react with the surface of the substrate (14) to form a radical terminated surface on the substrate (14). The reaction chamber (10) is purged and a second gaseous precursor is introduced. A second electromagnetic radiation pulse is initiated and forms second radical species. The second radical species of the second gas react with the surface to form a film on the substrate (14). Alternately, the gaseous species can be chosen to produce radicals that result in the removal of material from the surface of the substrate (14).