Search

SrTiO3 (STO) films are grown via atomic layer deposition at 370 °C with a two‐step growth method. A 5‐nm‐thick seed layer is first deposited and annealed via rapid thermal annealing (RTA) at temperatures ranging from 450 to 650 °C, and the main layer is subsequently grown on the annealed seed layer for in situ crystallization. When the RTA temperature is 500 °C or lower, the seed layer remains amorphous, and the main layer is also grown in the amorphous phase. At the 550 °C seed annealing temperature, the STO film is partially crystallized, and at the higher annealing temperature, the STO main layer is fully crystallized. The oxygen diffuses through the vertically aligned grain‐boundaries during the crystallized film growth, which induces the oxidation–reduction reaction of the underlying Ru substrate. This reaction causes a higher growth rate in the crystalline phase. The large growth rate difference between the amorphous and crystalline regions induces a severe roughening of the main layer. When RTA is done at 600 °C, the film is mostly crystallized, and the main layer becomes smooth again. Consequently, a 0.52 nm equivalent oxide thickness is achieved with the low leakage current of 2.5 × 10−8 A cm−2 at the 0.8 V applied bias. [ABSTRACT FROM AUTHOR]

(GeTe2)(1–x)(Sb2Te3)x(GST) layerswere deposited via atomic layer deposition (ALD) at growth temperaturesranging from 50 to 120 °C using Ge(OCH3)4or Ge(OC2H5)4, Sb(OC2H5)3, and [(CH3)3Si]2Te as the metal–organic precursors of the Ge, Sb, andTe elements, respectively. The GST layers with compositions lyingon the GeTe2–Sb2Te3tie linescould be obtained by varying the ratio of the Ge–Te and Sb–TeALD cycles. Although the incorporation of an Sb–Te layer intothe GST film occurred in a genuine ALD manner, that of the Ge–Telayer was governed by the kinetically limited physisorption of Geprecursors. The incorporation behavior of the Ge precursor with differentligands was explained by the adsorption and desorption kinetics based on the Brunauer–Emmett–Tellerisotherm. The ALD-like film growth behavior could be well-explainedby the kinetically limited incorporation of Ge atoms. [ABSTRACT FROM AUTHOR]

Highlights: [•] Atomic-layer-deposited HfO2 films grown at extremely low temperatures (≤100°C) were examined. [•] Growth saturation behavior of ALD was observed near to room temperatures. [•] Effects of growth temperatures and O3 concentrations on film properties are reported in detail. [•] Grown HfO2 films exhibited acceptable properties for flexible display and bio-electronic applications. [ABSTRACT FROM AUTHOR]

Phase change random access memory appears to be the strongestcandidatefor next-generation high density nonvolatile memory. The fabricationof ultrahigh density phase change memory (≫1 Gb) depends heavilyon the thin film growth technique for the phase changing chalcogenidematerial, most typically containing Ge, Sb and Te (Ge–Sb–Te).Atomic layer deposition (ALD) at low temperatures is the most preferredgrowth method for depositing such complex materials over surfacespossessing extreme topology. In this study, [(CH3)3Si]2Te and stable alkoxy-Ge (Ge(OCH3)4) and alkoxy-Sb (Sb(OC2H5)3) metal–organic precursors were used to deposit variouslayers with compositions lying on the GeTe2–Sb2Te3tie lines at a substrate temperature as lowas 70 °C using a thermal ALD process. The adsorption of Ge precursorwas proven to be a physisorption type while other precursors showeda chemisorption behavior. However, the adsorption of Ge precursorwas still self-regulated, and the facile ALD of the pseudobinary solidsolutions with composition (GeTe2)(1-x)(Sb2Te3)xwereachieved. This chemistry-specific ALD process was quite robust againstprocess variations, allowing highly conformal, smooth, and reproduciblefilm growth over a contact hole structure with an extreme geometry.The detailed ALD behavior of binary compounds and incorporation behaviorsof the binary compounds in pseudobinary solid solutions were studiedin detail. This new composition material showed reliable phase changeand accompanying resistance switching behavior, which were slightlybetter than the standard Ge2Sb2Te5material in the nanoscale. The local chemical environment was similarto that of conventional Ge2Sb2Te5materials. [ABSTRACT FROM AUTHOR]