Plasma-Enhanced Atomic Layer Deposition of Molybdenum Oxide Thin Films at Low Temperatures for Hydrogen Gas Sensing.

Molybdenum oxide thin films are very appealing for gas sensing applications due to their tunable material characteristics. Particularly, the growing demand for developing hydrogen sensors has triggered the exploration of functional materials such as molybdenum oxides (MoO). Strategies to enhance the performance of MoO-based gas sensors include nanostructured growth accompanied by precise control of composition and crystallinity.

Microscopic Diffusion of Atomic Hydrogen and Water in HER Catalyst MoS Revealed by Neutron Scattering.

The design of novel and abundant catalytic materials for electrolysis is crucial for reaching carbon neutrality of the global energy system. A deliberate approach to catalyst design requires both theoretical and experimental knowledge not only of the target reactions but also of the supplementary mechanisms affecting the catalytic activity. In this study, we focus on the interplay of hydrogen mobility and reactivity in the hydrogen evolution reaction catalyst MoS.

CVD Grown Tungsten Oxide for Low Temperature Hydrogen Sensing: Tuning Surface Characteristics via Materials Processing for Sensing Applications.

The intrinsic properties of semiconducting oxides having nanostructured morphology are highly appealing for gas sensing. In this study, the fabrication of nanostructured WO thin films with promising surface characteristics for hydrogen (H ) gas sensing applications is accomplished. This is enabled by developing a chemical vapor deposition (CVD) process employing a new and volatile tungsten precursor bis(diisopropylamido)-bis(tert-butylimido)-tungsten(VI), [W(N Bu) (N Pr ) ].

SnO deposition water based ALD employing tin(II) formamidinate: precursor characterization and process development.

Tin monoxide (SnO) is a promising oxide semiconductor which is appealing for a wide range of applications from channel materials in p-type field effect transistors (FET) to electrode materials searched for next-generation batteries. For the controlled growth of SnO films at low temperatures, atomic layer deposition (ALD) is employed in this study, where the choice of the precursor plays a significant role. A comparative thermal evaluation of four different amidinate-based tin(II) precursors and the influence of the ligand sphere on their physicochemical properties revealed that bis(,'-diisopropylformamidinato tin(II) (1) possesses the required volatility, good thermal stability and sufficient reactivity towards water, to be implemented as the ALD precursor.

Role of Anionic Backbone in NHC-Stabilized Coinage Metal Complexes: New Precursors for Atomic Layer Deposition.

Cu and Ag precursors that are volatile, reactive, and thermally stable are currently of high interest for their application in atomic-layer deposition (ALD) of thin metal films. In pursuit of new precursors for coinage metals, namely Cu and Ag, a series of new N-heterocyclic carbene (NHC)-based Cu and Ag complexes were synthesized. Modifications in the substitution pattern of diketonate-based anionic backbones led to five monomeric Cu complexes and four closely related Ag complexes with the general formula [M( NHC)(R)] (M=Cu, Ag; NHC=1,3-di-tert-butyl-imidazolin-2-ylidene; R=diketonate).

CVD grown GaSbN films as visible-light active photoanodes.

The III-V semiconductor GaN is a promising material for photoelectrochemical (PEC) cells, however the large bandgap of 3.45 eV is a considerable hindrance for the absorption of visible light. Therefore, the substitution of small amounts of N anions by isovalent Sb is a promising route to lower the bandgap and thus increase the PEC activity under visible light.

A study on the influence of ligand variation on formamidinate complexes of yttrium: new precursors for atomic layer deposition of yttrium oxide.

The synthesis and characterization of a series of closely related Y(III) compounds comprising the formamidinate ligands (RNCHNR) (R = alkyl) is reported, with the scope of using them as prospective precursors for atomic layer deposition (ALD) of yttrium oxide (YO) thin films. The influence of the side chain variation on the thermal properties of the resulting complexes is studied and benchmarked by thermal analysis and vapor pressure measurements. Density functional theory (DFT) studies give theoretical insights into the reactivity of the compounds towards water, which was targeted as a co-reactant for the deposition of YO thermal ALD in the next step.

Influence of low Bi contents on phase transformation properties of VO studied in a VO:Bi thin film library.

A thin-film materials library in the system V-Bi-O was fabricated by reactive co-sputtering. The composition of Bi relative to V was determined by Rutherford backscattering spectroscopy, ranging from 0.06 to 0.

Band-Gap Tuning in All-Inorganic CsPbSnBr Perovskites.

We investigate all-inorganic perovskite CsPbSnBr thin films to determine the variations in the band gap and electronic structure associated with the Pb/Sn ratio. We observe that the band gap can be tuned between 1.86 eV ( = 0) and 2.

Atomic layer deposition of dielectric YO thin films from a homoleptic yttrium formamidinate precursor and water.

We report the application of tris(,'-diisopropyl-formamidinato)yttrium(iii) [Y(DPfAMD)] as a promising precursor in a water-assisted thermal atomic layer deposition (ALD) process for the fabrication of high quality YO thin films in a wide temperature range of 150 °C to 325 °C. This precursor exhibits distinct advantages such as improved chemical and thermal stability over the existing YO ALD precursors including the homoleptic and closely related yttrium tris-amidinate [Y(DPAMD)] and tris-guanidinate [Y(DPDMG)], leading to excellent thin film characteristics. Smooth, homogeneous, and polycrystalline (fcc) YO thin films were deposited at 300 °C with a growth rate of 1.

A carbene stabilized precursor for the spatial atomic layer deposition of copper thin films.

This paper demonstrates a carbene stabilized precursor [Cu(NHC)(hmds)] with suitable volatility, reactivity and thermal stability, that enables the spatial plasma-enhanced atomic layer deposition (APP-ALD) of copper thin films at atmospheric pressure. The resulting conductive and pure copper layers were thoroughly analysed and a comparison of precursor and process with the previously reported silver analogue [Ag(NHC)(hmds)] revealed interesting similarities and notable differences in precursor chemistry and growth characteristics. This first report of APP-ALD grown copper layers is an important starting point for high throughput, low-cost manufacturing of copper films for nano- and optoelectronic devices.

A new metalorganic chemical vapor deposition process for MoS with a 1,4-diazabutadienyl stabilized molybdenum precursor and elemental sulfur.

Molybdenum disulfide (MoS2) is known for its versatile properties and hence is promising for a wide range of applications. The fabrication of high quality MoS2 either as homogeneous films or as two-dimensional layers on large areas is thus the objective of intense research. Since industry requirements on MoS2 thin films can hardly be matched by established exfoliation fabrication methods, there is an enhanced need for developing new chemical vapor deposition (CVD) and atomic layer deposition (ALD) processes where a rational precursor selection is a crucial step.

Tuning Coordination Geometry of Nickel Ketoiminates and Its Influence on Thermal Characteristics for Chemical Vapor Deposition of Nanostructured NiO Electrocatalysts.

Nickel-based nanostructured materials have gained widespread attention, particularly for energy-related applications. Employing chemical vapor deposition (CVD) for NiO necessitates suitable nickel precursors that are volatile and stable. Herein, we report the synthesis and characterization of a series of new nickel β-ketoiminato complexes with different aliphatic and etheric side chain substitutions, namely, bis(4-(isopropylamino)-pent-3-en-2-onato)nickel(II) ([Ni(ipki)], ), bis(4-(2-methoxyethylamino)pent-3-en-2-onato)nickel(II) ([Ni(meki)], ), bis(4-(2-ethoxyethylamino)pent-3-en-2-onato)nickel(II) ([Ni(eeki)], ), bis(4-(3-methoxy-propylamino)-pent-3-en-2-onato)nickel(II) ([Ni(mpki)], ), and bis(4-(3-ethoxypropylamino)pent-3-en-2-onato)nickel(II) ([Ni(epki)], ).

Additive-free spin coating of tin oxide thin films: synthesis, characterization and evaluation of tin β-ketoiminates as a new precursor class for solution deposition processes.

The fabrication of SnOx in thin film form via chemical solution deposition (CSD) processes is favored over vacuum based techniques as it is cost effective and simpler. The precursor employed plays a central role in defining the process conditions for CSD. Particularly for processing SnO2 layers that are appealing for sensor or electronic applications, there are limited precursors available for CSD.

From Precursor Chemistry to Gas Sensors: Plasma-Enhanced Atomic Layer Deposition Process Engineering for Zinc Oxide Layers from a Nonpyrophoric Zinc Precursor for Gas Barrier and Sensor Applications.

The identification of bis-3-(N,N-dimethylamino)propyl zinc ([Zn(DMP) ], BDMPZ) as a safe and potential alternative to the highly pyrophoric diethyl zinc (DEZ) as atomic layer deposition (ALD) precursor for ZnO thin films is reported. Owing to the intramolecular stabilization, BDMPZ is a thermally stable, volatile, nonpyrophoric solid compound, however, it possesses a high reactivity due to the presence of Zn-C and Zn-N bonds in this complex. Employing this precursor, a new oxygen plasma enhanced (PE)ALD process in the deposition temperature range of 60 and 160 °C is developed.

Effects of the Ion to Growth Flux Ratio on the Constitution and Mechanical Properties of Cr-Al-N Thin Films.

Cr-Al-N thin film materials libraries were synthesized by combinatorial reactive high power impulse magnetron sputtering (HiPIMS). Different HiPIMS repetition frequencies and peak power densities were applied altering the ion to growth flux ratio. Moreover, time-resolved ion energy distribution functions were measured with a retarding field energy analyzer (RFEA).

Correction: Luminescent NdS thin films: a new chemical vapour deposition route towards rare-earth sulphides.

Correction for 'Luminescent NdS thin films: a new chemical vapour deposition route towards rare-earth sulphides' by Stefan Cwik et al., Dalton Trans., 2019, 48, 2926-2938.

Room-Temperature Stimulated Emission and Lasing in Recrystallized Cesium Lead Bromide Perovskite Thin Films.

Cesium lead halide perovskites are of interest for light-emitting diodes and lasers. So far, thin-films of CsPbX have typically afforded very low photoluminescence quantum yields (PL-QY < 20%) and amplified spontaneous emission (ASE) only at cryogenic temperatures, as defect related nonradiative recombination dominated at room temperature (RT). There is a current belief that, for efficient light emission from lead halide perovskites at RT, the charge carriers/excitons need to be confined on the nanometer scale, like in CsPbX nanoparticles (NPs).

PEALD of HfO Thin Films: Precursor Tuning and a New Near-Ambient-Pressure XPS Approach to in Situ Examination of Thin-Film Surfaces Exposed to Reactive Gases.

A bottom-up approach starting with the development of new Hf precursors for plasma-enhanced atomic layer deposition (PEALD) processes for HfO followed by in situ thin-film surface characterization of HfO upon exposure to reactive gases via near-ambient-pressure X-ray photoelectron spectroscopy (NAP-XPS) is reported. The stability of thin films under simulated operational conditions is assessed, and the successful implementation of HfO dielectric layers in metal-insulator-semiconductor (MIS) capacitors is demonstrated. Among the series of newly synthesized mono-guanidinato-tris-dialkyl-amido class of Hf precursors, one of them, namely, [Hf{η-(PrN)CNEtMe}(NEtMe)], was representatively utilized with oxygen plasma, resulting in a highly promising low-temperature PEALD process at 60 °C.

Low-Temperature Plasma-Enhanced Atomic Layer Deposition of Tin(IV) Oxide from a Functionalized Alkyl Precursor: Fabrication and Evaluation of SnO-Based Thin-Film Transistor Devices.

A bottom-up process from precursor development for tin to plasma-enhanced atomic layer deposition (PEALD) for tin(IV) oxide and its successful implementation in a working thin-film transistor device is reported. PEALD of tin(IV) oxide thin films at low temperatures down to 60 °C employing tetrakis-(dimethylamino)propyl tin(IV) [Sn(DMP)] and oxygen plasma is demonstrated. The liquid precursor has been synthesized and thoroughly characterized with thermogravimetric analyses, revealing sufficient volatility and long-term thermal stability.

Luminescent NdS thin films: a new chemical vapour deposition route towards rare-earth sulphides.

Neodymium sulphide (Nd2S3) belongs to the exciting class of rare earth sulphides (RES) and is projected to have a serious potential in a wide spectrum of application either in pure form or as dopant. We demonstrate a facile and first growth of Nd2S3 thin films via metal-organic chemical vapour deposition (MOCVD) at moderate process conditions using two new Nd precursors, namely tris(N,N'-diisopropyl-2-dimethylamido-guanidinato)Nd(iii) and tris(N,N'-diisopropyl-acetamidinato)Nd(iii). The promising thermal properties and suitable reactivity of both Nd precursors towards elemental sulphur enabled the formation of high purity γ-Nd2S3.

Implantation of defined activities of phosphorus 32 with reduced target damage.

Materials doped with the unstable isotope phosphorus 32 are promising candidates for use in brachytherapeutic applications. One way to dope a material with P is by ion implantation. However, the bombardment of the target with ions other than P due to impurities of the ion beam leads to unnecessary damages of the target, which might reduce its potential for medical applications.