In Situ IR Spectroscopy Studies of Atomic Layer-Deposited SnO on Fullerenes for Perovskite Photovoltaics.

In recent years, atomic layer deposition (ALD) has established itself as the state-of-the-art technique for the deposition of SnO buffer layers grown between the fullerene electron transport layer (ETL) and the ITO top electrode in metal halide perovskite-based photovoltaics. The SnO layer shields the underlying layers, i.e.

Correction to Nb Doping and Alloying of 2D WS by Atomic Layer Deposition for 2D Transition Metal Dichalcogenide Transistors and HER Electrocatalysts.

[This corrects the article DOI: 10.1021/acsanm.4c00094.

In situ formation of inhibitor species through catalytic surface reactions during area-selective atomic layer deposition of TaN.

Small molecule inhibitors (SMIs) have been gaining attention in the field of area-selective atomic layer deposition (ALD) because they can be applied in the vapor-phase. A major challenge for SMIs is that vapor-phase application leads to a disordered inhibitor layer with lower coverage as compared to self-assembled monolayers, SAMs. A lower coverage of SMIs makes achieving high selectivity for area-selective ALD more challenging.

Nb Doping and Alloying of 2D WS by Atomic Layer Deposition for 2D Transition Metal Dichalcogenide Transistors and HER Electrocatalysts.

We utilize plasma-enhanced atomic layer deposition to synthesize two-dimensional Nb-doped WS and NbWS alloys to expand the range of properties and improve the performance of 2D transition metal dichalcogenides for electronics and catalysis. Using a supercycle deposition process, films are prepared with compositions spanning the range from WS to NbS. While the W-rich films form crystalline disulfides, the Nb-rich films form amorphous trisulfides.

In Situ IR Spectroscopy Studies of Atomic Layer-Deposited SnO on Formamidinium-Based Lead Halide Perovskite.

Perovskite photovoltaics has achieved conversion efficiencies of 26.0% by optimizing the optoelectronic properties of the absorber and its interfaces with charge transport layers (CTLs). However, commonly adopted organic CTLs can lead to parasitic absorption and device instability.

Toolbox of Advanced Atomic Layer Deposition Processes for Tailoring Large-Area MoS Thin Films at 150 °C.

Two-dimensional MoS is a promising material for applications, including electronics and electrocatalysis. However, scalable methods capable of depositing MoS at low temperatures are scarce. Herein, we present a toolbox of advanced plasma-enhanced atomic layer deposition (ALD) processes, producing wafer-scale polycrystalline MoS films of accurately controlled thickness.

Surface Smoothing by Atomic Layer Deposition and Etching for the Fabrication of Nanodevices.

In many nano(opto)electronic devices, the roughness at surfaces and interfaces is of increasing importance, with roughness often contributing toward losses and defects, which can lead to device failure. Consequently, approaches that either limit roughness or smoothen surfaces are required to minimize surface roughness during fabrication. The atomic-scale processing techniques atomic layer deposition (ALD) and atomic layer etching (ALE) have experimentally been shown to smoothen surfaces, with the added benefit of offering uniform and conformal processing and precise thickness control.

Atomic Layer Deposition of Large-Area Polycrystalline Transition Metal Dichalcogenides from 100 °C through Control of Plasma Chemistry.

Two-dimensional transition metal dichalcogenides, such as MoS, are intensely studied for applications in electronics. However, the difficulty of depositing large-area films of sufficient quality under application-relevant conditions remains a major challenge. Herein, we demonstrate deposition of polycrystalline, wafer-scale MoS, TiS, and WS films of controlled thickness at record-low temperatures down to 100 °C using plasma-enhanced atomic layer deposition.

Relation between Reactive Surface Sites and Precursor Choice for Area-Selective Atomic Layer Deposition Using Small Molecule Inhibitors.

Implementation of vapor/phase dosing of small molecule inhibitors (SMIs) in advanced atomic layer deposition (ALD) cycles is currently being considered for bottom-up fabrication by area-selective ALD. When SMIs are used, it can be challenging to completely block precursor adsorption due to the inhibitor size and the relatively short vapor/phase exposures. Two strategies for precursor blocking are explored: (i) physically covering precursor adsorption sites, i.

Plasma-Enhanced Atomic Layer Deposition of HfO with Substrate Biasing: Thin Films for High-Reflective Mirrors.

Tuning ion energies in plasma-enhanced atomic layer deposition (PEALD) processes enables fine control over the material properties of functional coatings. The growth, structural, mechanical, and optical properties of HfO thin films are presented in detail toward photonic applications. The influence of the film thickness and bias value on the properties of HfO thin films deposited at 100 °C using tetrakis(dimethylamino)hafnium (TDMAH) and oxygen plasma using substrate biasing is systematically analyzed.

PO /AlO Stacks for c-Si Surface Passivation: Material and Interface Properties.

Phosphorus oxide (PO ) capped by aluminum oxide (AlO) has recently been discovered to provide excellent surface passivation of crystalline silicon (c-Si). In this work, insights into the passivation mechanism of PO /AlO stacks are gained through a systematic study of the influence of deposition temperature ( = 100-300 °C) and annealing temperature ( = 200-500 °C) on the material and interface properties. It is found that employing lower deposition temperatures enables an improved passivation quality after annealing.

On the Contact Optimization of ALD-Based MoS FETs: Correlation of Processing Conditions and Interface Chemistry with Device Electrical Performance.

Despite the extensive ongoing research on MoS field effect transistors (FETs), the key role of device processing conditions in the chemistry involved at the metal-to-MoS interface and their influence on the electrical performance are often overlooked. In addition, the majority of reports on MoS contacts are based on exfoliated MoS, whereas synthetic films are even more susceptible to the changes made in device processing conditions. In this paper, working FETs with atomic layer deposition (ALD)-based MoS films and Ti/Au contacts are demonstrated, using current-voltage (-) characterization.

Impact of Ions on Film Conformality and Crystallinity during Plasma-Assisted Atomic Layer Deposition of TiO.

This work demonstrates that ions have a strong impact on the growth per cycle (GPC) and material properties during plasma-assisted atomic layer deposition (ALD) of TiO (titanium dioxide), even under mild plasma conditions with low-energy (<20 eV) ions. Using vertical trench nanostructures and microscopic cavity structures that locally block the flux of ions, it is observed that the impact of (low-energy) ions is an important factor for the TiO film conformality. Specifically, it is demonstrated that the GPC in terms of film thickness can increase by 20 to >200% under the influence of ions, which is correlated with an increase in film crystallinity and an associated strong reduction in the wet etch rate (in 30:1 buffered HF).

Oxygen Recombination Probability Data for Plasma-Assisted Atomic Layer Deposition of SiO and TiO.

Atomic layer deposition (ALD) can provide nanometer-thin films with excellent conformality on demanding three-dimensional (3D) substrates. This also holds for plasma-assisted ALD, provided that the loss of reactive radicals through surface recombination is sufficiently low. In this work, we determine the surface recombination probability of oxygen radicals during plasma ALD of SiO and TiO for substrate temperatures from 100 to ∼240 °C and plasma pressures from 12 to 130 mTorr (for SiO).

Atomic insights into the oxygen incorporation in atomic layer deposited conductive nitrides and its mitigation by energetic ions.

Oxygen is often detected as impurity in metal and metal nitride films prepared by atomic layer deposition (ALD) and its presence has profound and adverse effects on the material properties. In this work, we present the case study of HfN films prepared by plasma-assisted ALD by alternating exposures of CpHf(NMe) and H plasma. First, we identify the primary source of O contamination in the film.

Electrochemical Activation of Atomic Layer-Deposited Cobalt Phosphate Electrocatalysts for Water Oxidation.

The development of efficient and stable earth-abundant water oxidation catalysts is vital for economically feasible water-splitting systems. Cobalt phosphate (CoPi)-based catalysts belong to the relevant class of nonprecious electrocatalysts studied for the oxygen evolution reaction (OER). In this work, an in-depth investigation of the electrochemical activation of CoPi-based electrocatalysts by cyclic voltammetry (CV) is presented.

Reaction Mechanisms during Atomic Layer Deposition of AlF Using Al(CH) and SF Plasma.

Metal fluorides generally demonstrate a wide band gap and a low refractive index, and they are commonly employed in optics and optoelectronics. Recently, an SF plasma was introduced as a novel co-reactant for the atomic layer deposition (ALD) of metal fluorides. In this work, the reaction mechanisms underlying the ALD of fluorides using a fluorine-containing plasma are investigated, considering aluminum fluoride (AlF) ALD from Al(CH) and an SF plasma as a model system.

Conformal Growth of Nanometer-Thick Transition Metal Dichalcogenide TiS -NbS Heterostructures over 3D Substrates by Atomic Layer Deposition: Implications for Device Fabrication.

The scalable and conformal synthesis of two-dimensional (2D) transition metal dichalcogenide (TMDC) heterostructures is a persisting challenge for their implementation in next-generation devices. In this work, we report the synthesis of nanometer-thick 2D TMDC heterostructures consisting of TiS -NbS on both planar and 3D structures using atomic layer deposition (ALD) at low temperatures (200-300 °C). To this end, a process was developed for the growth of 2D NbS by thermal ALD using (-butylimido)-tris-(diethylamino)-niobium (TBTDEN) and HS gas.

Nanoscale Encapsulation of Perovskite Nanocrystal Luminescent Films via Plasma-Enhanced SiO Atomic Layer Deposition.

Photoluminescence perovskite nanocrystals (NCs) have shown significant potential in optoelectronic applications in view of their narrow band emission with high photoluminescence quantum yields and color tunability. The main obstacle for practical applications is to obtain high durability against an external environment. In this work, a low temperature (50 °C) plasma-enhanced atomic layer deposition (PE-ALD) protection strategy was developed to stabilize CsPbBr NCs.

Atomic Layer Deposition of Al-Doped MoS: Synthesizing a p-type 2D Semiconductor with Tunable Carrier Density.

Extrinsically doped two-dimensional (2D) semiconductors are essential for the fabrication of high-performance nanoelectronics among many other applications. Herein, we present a facile synthesis method for Al-doped MoS via plasma-enhanced atomic layer deposition (ALD), resulting in a particularly sought-after -type 2D material. Precise and accurate control over the carrier concentration was achieved over a wide range (10 up to 10 cm) while retaining good crystallinity, mobility, and stoichiometry.

Area-Selective Atomic Layer Deposition of Two-Dimensional WS Nanolayers.

With downscaling of device dimensions, two-dimensional (2D) semiconducting transition metal dichalcogenides (TMDs) such as WS are being considered as promising materials for future applications in nanoelectronics. However, at these nanoscale regimes, incorporating TMD layers in the device architecture with precise control of critical features is challenging using current top-down processing techniques. In this contribution, we pioneer the combination of two key avenues in atomic-scale processing: area-selective atomic layer deposition (AS-ALD) and growth of 2D materials, and demonstrate bottom-up processing of 2D WS nanolayers.

Probing the Origin and Suppression of Vertically Oriented Nanostructures of 2D WS Layers.

Two-dimensional (2D) layered transition metal dichalcogenides (TMDs) such as WS are promising materials for nanoelectronic applications. However, growth of the desired horizontal basal-plane oriented 2D TMD layers is often accompanied by the growth of vertical nanostructures that can hinder charge transport and, consequently, hamper device application. In this work, we discuss both the formation and suppression of vertical nanostructures during plasma-enhanced atomic layer deposition (PEALD) of WS.

Low-Temperature Phase-Controlled Synthesis of Titanium Di- and Tri-sulfide by Atomic Layer Deposition.

Phase-controlled synthesis of two-dimensional (2D) transition-metal chalcogenides (TMCs) at low temperatures with a precise thickness control has to date been rarely reported. Here, we report on a process for the phase-controlled synthesis of TiS (metallic) and TiS (semiconducting) nanolayers by atomic layer deposition (ALD) with precise thickness control. The phase control has been obtained by carefully tuning the deposition temperature and coreactant composition during ALD.