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Nano-/microplastics (NP) is a human-made emerging contaminant with worldwide occurrence. The small size (below one micrometer), the different chemical nature and the persistence make NP to potential hazards with suspect probability of tissue penetration and inflammation or as accumulator for toxins. A strategy to stop the spill of novel NP is the remediation from waste water or rivers as prominent distributors. We have developed core–shell superparamagnetic iron oxide nanoparticles (SPIONs) that attract NP and glue them to larger agglomerates which then can be removed from water by applying an external magnetic field. The shell molecules provide two interaction motifs towards NP. The tuned surface potential of the functionalized SPIONs attract complementary charged NP efficiently and the n-alkyl chain is dedicated to preferential interaction towards organic NP rather than inorganic particles. Structural analytics and molecular dynamics simulation support the proposed concept. Systematic remediation experiments with different NP (chemical structures, sizes and mixtures), from different waters – including river water – and with different SPION core materials indicate a universal validity of the concept, with best remediation performance for mixed NP. We suggest a method for broadband remediation of various NP with simple materials and processes, which both have the potential to be up-scaled.

Polycyclic aromatic hydrocarbons with zigzag peripheries are high perspective candidates for organic electronics. However, large fused acenes are still poorly studied due to the tedious synthesis. Herein we report a non-substituted fused bistetracene DBATT (2.3,8.9-dibenzanthanthrene) as the semiconductor on low-voltage-driven organic thin-film transistors. The systematic studies of thin-film growth on various self-assembled monolayer (SAM) modified gate dielectrics and the electrical performances were carried out. The sub-monolayer of the semiconductor film shows larger island domains on the alkyl chain SAM. This device exhibits the hole mobility of 0.011 cm2·V−1·s−1 with a current ratio of IonIIoff above 105.

The study of hydrogen bonding interactions at the level of functionalized nanoparticles remains highly challenging and poorly explored area. In this work, superparamagnetic iron oxide nanoparticles (SPIONs) were orthogonally functionalized using receptors bearing multiple hydrogen bonding motifs. Pristine SPIONs were modified by wet chemical processes with Hamilton receptors (hosts), or cyanurate‐guest molecules linked to phosphonic acid moieties for monolayer functionalization. The modified surfaces were fully characterized and the number of attached ligands on the surface were determined. The host‐guest interactions on the interface of modified SPIONs were investigated by using UV‐Vis spectroscopic titrations. Functionalized SPIONs demonstrated two to three magnitudes stronger binding affinities as compared to the related molecular interactions in solution due to synergistic effects on complex surface environment. Higher supramolecular binding ratios of host‐guest interactions on the modified surface were emerged. These studies provide fundamental insights into supramolecular complexations on the surface at solid‐liquid interface systems with applications in engineered nanomaterials, nano‐sensing devices, and drug delivery systems.

The transition-metal dichalcogenide HfS2 is a promising alternative semiconductor with adequate band gap and high carrier mobility. However, a controllable growth of continuous HfS2 films with selectivity for specific surfaces at a low temperature on a large scale has not been demonstrated yet. Herein, HfS2 films are grown at 100 °C by atomic layer deposition (ALD) based on the precursors tetrakis(dimethylamido)hafnium and H2S. In situ vibrational spectroscopy allows for the definition of the temperature range over which (Me2N)4Hf chemisorbs as one monolayer. In that range, sequential exposures of the solid surface with (Me2N)4Hf and H2S result in self-limiting reactions that yield alternating surface termination with dimethylamide and thiol. Repeating the cycle grows smooth, continuous, stoichiometric films of thicknesses adjustable from angstroms to >100 nm, as demonstrated by spectroscopic ellipsometry, XRR, AFM, UV–vis and Raman spectroscopy, XPS, and TEM. The well-defined surface chemistry enables one to deposit HfS2 selectively using, for example, patterns generated in molecular selfassembled monolayers. This novel ALD reaction combines several attractive features necessary for integrating HfS2 into devices.

Flat TiO$_2$ layers are deposited by magnetron sputtering on Ti/Si wafers. The TiO$_2$ surfaces are then sputter-coated with thin Au films of a nominal thickness of 0.5-10 nm that are converted by solid-state dewetting into Au nanoparticles of tuneable size and spacing; the Au nanoparticle size can be tuned over a broad range, i.e. ca. 3-200 nm. The Au-decorated TiO$_2$ surfaces enable plasmonic photo-electrochemical water splitting under visible light illumination (450-750 nm). The water splitting performance reaches a maximum for TiO$_2$ layers decorated with ~ 30 nm-sized Au particles. As expected, optical absorption measurements show a red shift of the plasmonic extinction band with increasing the Au nanoparticle size. However, the plasmonic photocurrent is found to peak at ~ 600 nm regardless of the size of the Au nanoparticles, i.e. the plasmonic photocurrent band position is size-independent. Such a remarkable observation can be ascribed to a hot electron injection cut-off effect.

The sensing capabilities of semiconducting metal oxide (SMO)-based gas sensors, which are a promising type of sensors, were improved in the present study using a novel method that enhanced gas selectivity toward various gas molecules. A simple and effective post-modification with functional self-assembled monolayer (SAM) molecules enhanced the selective sensing properties. The chemical-affinity-driven interaction between SAM and gas molecules enabled selective gas sensing, and the small size of SnO2 nanowires (NWs; diameter = ~50 nm) provided a large sensing area. Moreover, simple alteration of the chemical moiety in SAM molecules facilitated the tuning of SAM-induced selectivity over a broad range of collections. The binding of SAMs on the NWs was analyzed by infrared spectroscopy, thermogravimetric analysis, and X-ray photoelectron spectroscopy, with the selective gas sensing being investigated under various sensing conditions. The results from the molecular dynamics simulations supported the proposed selective sensing mechanism. The combination of passivation and selective gas sensing resulted in a simple method for the selective gas sensing of SnO2 NWs, and the concept could be generally expanded to other types of SMO-based sensing platforms.

Generating oxygen vacancies on the metal oxides is an effective way to control their sensing properties. Furthermore, embossing surfaces are preferred to the flat surfaces for sensing studies due to providing of more adsorption sites, which is another key parameter for improvement of the gas sensing characteristics. In this study, we generated oxygen vacancies on SnO2 nanowires (NWs) by femtosecond (FS) laser irradiation with the different laser pulse energies of 0.025, 0.05, and 0.075 μJ, corresponding to the laser fluences of 138, 276, and 414 mJ/cm2. We investigated the effect of the FS laser irradiation on the response of the fabricated SnO2 NW gas sensors toward NO2 and toluene (C7H8) gases. The created oxygen vacancies and the response of the sensors were linked to the laser pulse energy. By studying the gas sensing characteristics of the sensors at various temperatures, we found that at 300 °C, the sensor irradiated at 0.025 μJ showed the highest response to C7H8, and the FS laser-irradiated sensors showed a lower response to the NO2 gas as compared to that of the non-irradiated sensor. The sensing mechanism of the gas sensors was comprehensively explained in terms of radial modulation of the SnO2 NWs, formation of SnO2 NW homojunctions, formation of embossing surfaces (increase of surface area) as well as formation of oxygen vacancies as a result of laser irradiation.

Efficient magnetic reactive oxygen species (ROS) formation enhancing agents after X-ray treatment are realized by functionalizing superparamagnetic magnetite (Fe3 O4 ) and Co-ferrite (CoFe2 O4 ) nanoparticles with self-assembled monolayers (SAMs). The Fe3 O4 and CoFe2 O4 nanoparticles are synthesized using Massart's coprecipitation technique. Successful surface modification with the SAM forming compounds 1-methyl-3-(dodecylphosphonic acid) imidazolium bromide, or (2-{2-[2-hydroxy-ethoxy]-ethoxy}-ethyl phosphonic acid provides biocompatibility and long-term stability of the Fe3 O4 and CoFe2 O4 nanoparticles in cell media. The SAM-stabilized ferrite nanoparticles are characterized with dynamic light scattering, X-ray powder diffraction, a superconducting quantum interference device, Fourier transform infrared attenuated total reflectance spectroscopy, zeta potential measurements, and thermogravimetric analysis. The impact of the SAM-stabilized nanoparticles on the viability of the MCF-7 cells and healthy human umbilical vein endothelial cells (HUVECs) is assessed using the neutral red assay. Under X-ray exposure with a single dosage of 1 Gy the intracellular SAM stabilized Fe3 O4 and CoFe2 O4 nanoparticles are observed to increase the level of ROS in MCF-7 breast cancer cells but not in healthy HUVECs. The drastic ROS enhancement is associated with very low dose modifying factors for a survival fraction of 50%. This significant ROS enhancement effect by SAM-stabilized Fe3 O4 and CoFe2 O4 nanoparticles constitutes their excellent applicability in radiation therapy.

The objective of this study was to examine the fate of foodborne pathogens (Bacillus cereus, Escherichia coli O157:H7, Listeria monocytogenes, Salmonella Typhimurium, and Staphylococcus aureus) and B. cereus spores in Korean turbid rice wine (Makgeolli). Samples of sterilized and non-sterilized turbid rice wine were inoculated with each of the vegetative bacteria or B. cereus spores at 3–4 log CFU/ml. The samples were stored at 5 °C or 22 °C, and bacterial survival was monitored over 28 days. Despite the harsh environment (alcohol content: 6–7% and pH: 3.43–3.98), long-term survival of pathogens was observed. Survival time was different depending on the type of beverage (pathogens survived longer in sterilized wine than in non-sterilized wine), cellular state (spores survived longer than vegetative cells), species (B. cereus survived longer than other species), and storage temperature (pathogens survived longer at 5 °C then at 22 °C). The number of B. cereus spores remained constant at both temperatures. The vegetative B. cereus population declined rapidly within 1 day, but then remained steady for up to 28 days (1.20–1.55 log CFU/ml in sterile wine). These results indicate that B. cereus formed spores that survived for a long time; therefore, it is possible that B. cereus may exist as spores in turbid rice wine. E. coli O157:H7, L. monocytogenes, S. Typhimurium, and S. aureus survived for up to 28, 14, 14, and 14 days, respectively, in sterilized wine at 5 °C. Thus, the health implications of the long-term survival of pathogens in alcoholic beverages should be carefully considered. The results provide new information that may be useful in predicting the potential microbiological hazards associated with turbid rice wine.

Various electron and hole transport layers have been used to develop high-efficiency perovskite solar cells. To achieve low-temperature solution processing of perovskite solar cells, organic n-type materials are employed to replace the metal oxide electron transport layer (ETL). Although PCBM (phenyl-C61-butyric acid methyl ester) has been widely used for this application, its morphological instability in films (i.e., aggregation) is detrimental. Herein, we demonstrate the synthesis of a new fullerene derivative (isobenzofulvene-C60-epoxide, IBF-Ep) that serves as an electron transporting material for methylammonium mixed lead halide-based perovskite (CH3NH3PbI(3-x)Cl(x)) solar cells, both in the normal and inverted device configurations. We demonstrate that IBF-Ep has superior morphological stability compared to the conventional acceptor, PCBM. IBF-Ep provides higher photovoltaic device performance as compared to PCBM (6.9% vs 2.5% in the normal and 9.0% vs 5.3% in the inverted device configuration). Moreover, IBF-Ep devices show superior tolerance to high humidity (90%) in air. By reaching power conversion efficiencies up to 9.0% for the inverted devices with IBF-Ep as the ETL, we demonstrate the potential of this new material as an alternative to metal oxides for perovskite solar cells processed in air.

In this study, a 2in. sized a highly periodic nanometer-scaled patterned sapphire substrate (NPSS) was fabricated using nanoimprint lithography (NIL) and inductively coupled plasma etching to improve the light-extraction efficiency of GaN-based light-emitting diodes (LEDs). A blue LED structure was grown on the nanometer-scale patterned sapphire substrates, and the photoluminescence (PL) and electroluminescence (EL) were measured to confirm the effectiveness of the nanometer-scaled patterns on sapphire. An improvement in luminescence efficiency was observed when NPSS was applied; 2 times stronger PL intensity and 2.8 times stronger EL intensity than the LED structure grown on the unpatterned sapphire wafers were measured. These results show highly periodic nanometer-scaled patterns create multi-photon scattering and effectively enhance the light-extraction efficiency of LEDs.

ZnO nano-structures were formed on transparent conducting oxide layer of GaN LED device on non-patterned (non-PSS) and patterned sapphire substrates (PSS). Since ZnO nano-structures were formed by sol-gel direct imprinting process, plasma etching process, which may create the plasma induced damage, was not used. Due to the ZnO nano-structures, light extracted from active layer was coupled with ZnO nano-structures and thus total internal reflection at the ITO layer was suppressed. According to electroluminescence measurement, the emission intensities of GaN LED devices with ZnO nano-structures, on both non-PSS and PSS sapphire substrates were increased by 20.5% and 19.0%, respectively, compared to GaN LED devices without ZnO nano-structures, due to the suppression of total internal reflection. Moreover, it is confirmed that there is no decrease of light extraction on side direction due to light focusing to vertical axis by nanostructure. Electrical performance of GaN LED devices were not degraded by ZnO sol-gel direct imprinting process.

Hexagonal arrays of submicron polymer patterns with a high refractive index were fabricated on a vertical light-emitting diode (LED) device by means of nanoimprint lithography (NIL) to improve the light extraction efficiency. An organic-inorganic hybrid resin containing a polymeric titanium dioxide precursor was spin-coated on the n-GaN top layer of a vertical LED wafer. The coated layer was then imprinted for 10 min with an elastomeric polydimethylsiloxane stamp at 200 °C and 5 atm. The NIL process formed pillar patterns on the n-GaN layer of the vertical LED wafer. The pillar patterns have a high refractive index ( n ≈ 2.0) in the visible wavelength range; they also have a diameter of 200 nm and a pitch of 700 nm. The light output power of the patterned vertical LED device is 28% greater than that of a non-patterned vertical LED device with a driving current of 350 mA. The I–V characteristics of the vertical LED device confirm that the patterning process induces no electric degradation.

Non-polar a-plane GaN layers were grown on planar and hemispherical micro- and nano-patterned r-sapphire substrates (PSS) by metal organic chemical vapor deposition (MOCVD). Double Crystal X-ray Rocking Curve (DCXRC) and Transmission Electron Microscopy (TEM) analyses showed that the crystal quality of a-GaN grown on the micro-PSS was the best among three kinds of r-sapphire substrates, which was attributed to defect reduction through lateral overgrowth on the hemispherical patterns. The intensity of the near band-edge emission (NBE) at 3.4eV from a-GaN on the micro-PSS was increased by about 30 times compared with that of the conventional a-plane GaN on planar r-sapphire, while the yellow emission spectrum at 2.2eV was the lowest among the three samples. Comparison of the micro-photoluminescence mapping image and the cross-section TEM also showed high and low defect regions on the planar section and hemisphere, respectively.

A UV-imprinting process for a full wafer was developed to enhance the light extraction of GaN-based green light-emitting diodes (LEDs). A polyvinyl chloride flexible stamp was used in the imprinting process to compensate for the poor flatness of the LED wafer. Two-dimensional photonic crystal patterns with pitches ranging from 600 to 900 nm were formed on the p-GaN top cladding layer of a 2 inch diameter wafer using nanoimprint and reactive ion etching processes. As a result, the optical output power of the patterned LED device was increased by up to 44% at a driving current of 20 mA by suppressing the total internal reflection and enhancing the irregular scattering of photons at the patterned p-GaN surface.

Wafer-scale UV nanoimprint and dry etching processes were used to fabricate photonic crystal patterns on an indium tin oxide (ITO) top electrode of GaN-based green light-emitting diodes (LEDs). Photonic crystal patterns with pitches ranging from 600 to 900 nm were transferred to the entire 2-inch LED wafer. Plasma damage in the GaN crystal of the LED device was avoided because the GaN was covered by ITO layer and was not exposed to the etching plasma during the ITO dry etching process. Consequently, the electroluminescence intensity of the patterned LED devices was enhanced up to 25% at 20 mA of driving current, compared to the nonpatterned LED device, while the forward voltage was similar.

Various sized nano-patterns, ranging from 0.8 μm × 0.4 μm to 2.0 μm × 1.0 μm were formed on the p-GaN top cladding layer of green LED, in order to increase photon extraction efficiency by suppressing total internal reflection. Fabrication of nano-patterns was done by UV nanoimprint lithography and reactive ion etching of p-GaN using SiCl4 and Ar gases using SiO2 as an etch mask. The effect of various nano-patterns on top p-GaN layer was investigated by photoluminescence. Compared to LED structure without nano-patterns on top cladding layer, the LED structures with sub-micron sized nano-patterns exhibit up to four times stronger emission intensity. This implies that the photon extraction efficiency of LED structures was increased by nano-patterns on top p-GaN layer. However, the luminescence intensity of LED structures with patterns greater than a micron, was less increased.

Moth-eye structures were produced on a p-GaN top cladding layer by UV imprint and inductively coupled plasma (ICP) etch processes in order to improve the light extraction efficiency of GaN-based green light-emitting diodes (LEDs). The height and shape of moth-eye structures were adjusted by controlling the thickness of Cr mask layer and ICP etching time. The transmittance of LED device stacks with moth-eye structure was increased up to 1.5–2.5 times, compared to identical LED sample without moth-eye structure and the intensity of photoluminescence from the InGaN multi-quantum well layer of LED sample with moth-eye structure was 5–7 times higher than that of the LED sample without the moth-eye structure.

Objectives: We performd this study to determine the long-term results based on clinical and radiographic outcome comparison following either transtibial or tibial inlay technique, and to find out factors related to osteoarthritis after PCL reconstruction. Methods: Seventy-seven patients (77 knees) treated with the PCL reconstruction for chronic injuries constituted the study cohort. The 77 patients were divided into 2 groups, namely, transtibial (44 patients) and tibial inlay (33 patients). The mean time from injury to reconstruction was 12.2 months (range, 2 to 60 months), and their average follow-up was 142 months (range, 97 to 192 months). Outcomes were measured using Lysholm knee scores, Tegner activity scores, laxity test using Telos device, and development of osteoarthritis. Results: There was significant improvement of Lysholm knee scores, Tegner activity scores, and laxity test using Telos device between the preoperative values and final follow-up values ( P < .05). However, there was no significant difference in the final follow-up outcomes ( P > .05). The final follow-up radiographs according to International Knee Documentation Committee guidelines showed that 7 patients (22.7%) in transtibial group and 4 patients (18.2%) in tibial inlay group were rated as Grade C. We found correlation between meniscectomy and osteoarthritis, but other factors including reconstruction technique, sex, age, and posterior instability did not influence the arthritic changes in both groups (Fig 1). Conclusion: The clinical and radiographic outcomes between the two surgical techniques of PCL reconstruction were comparable. Osteoarthritis was observed in some patients with a significant proportion showing some loss of joint space, and factors except meniscectomy did not show correlation with development of osteoarthritis.

A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method as an alternative to a gas chromatography-thermal energy analyser (GC-TEA) method recommended by the European Committee on Standardization (CEN) was validated for the simultaneous determination of eight N-nitrosamines released into artificial saliva from rubber or elastomer teats and soothers. N-nitroso-dipropylamine-d₁₄ (NDPA-d₁₄) was used as internal standard for accurate quantification. The method was validated with relatively good analytical results, including sufficiently low limits of detection (0.1-2 µg kg⁻¹) of sample) and good linearity (r²> 0.99) throughout the studied concentration ranges. Intra- and inter-day precisions expressed with the relative standard deviation (RSD, %) were 3.4-8.0% and 4.4-11.3%, which were below the performance criteria based on one-half of the value derived from the Horwitz value. It was also found that the LC-MS/MS method is sufficiently rugged and successfully applicable to its routine analysis for the compliance test of Commission Directive 93/11/EEC.

In this study, a patterned ZnO nanorod array was formed on the ITO layer of GaN-based light-emitting diodes (LEDs), to increase the light extraction efficiency of the LED. The bi-layer imprinted resin pattern was used for selective growth of the ZnO nanorod array on the ITO layer. Compared to conventional LEDs grown on patterned sapphire substrate (PSS), the deposition of the blanket ZnO layer on the ITO layer increased the light extraction efficiency of the LED by about 10%. Further growth of the ZnO nanorod layer on the blanket ZnO layer increased the light extraction efficiency of the LED by about 23%. In the case that a patterned ZnO nanorod layer was formed on a blanket ZnO layer, the light extraction efficiency increased by about 34%. These enhancements of the device were caused by modulation of the refractive-index in ZnO layers and the surface roughening effects because of the unique design of the pattern, which was nanostructure-in-nanopattern, resulting in the formation of many escape cones on the LED surface.

In this paper, we present a novel microfluidic system with pulsatile cell storing, cell-delivering and cell culturing functions on a single PDMS platform. For this purpose, we have integrated two reservoirs, a pulsatile pumping system containing two soft check valves, which were fabricated by in situ photopolymerization, six switch valves, and three cell culture chambers all developed through a simple and rapid fabrication process. The sample volume delivered per stroke was 120 nl and the transported volume was linearly related to the pumping frequency. We have investigated the effect of the pulsatile pneumatic micropumping on the cells during transport. For this purpose, we pumped two types of cell suspensions, one containing human breast adenocarcinoma cells (MCF-7) and the other mesenchymal stem cells (hMSCs) derived from bone marrow. The effect of pulsatile pumping on both cell types was examined by short and long-term culture experiments. Our results showed that the characteristics of both cells were maintained; they were not damaged by the pumping system. Evaluations were carried out by morphological inspection, viability assay and immunophenotyping analysis. The delivered MCF-7 cells and hMSCs spread and proliferated onto the gelatin coated cell culture chamber. This total micro cell culture system can be applied to cell-based high throughput screening and for co-culture of different cells with different volume.

A TiO2 nano-structure was formed on the indium-tin-oxide electrode of a GaN-based light-emitting diode (LED) in order to enhance the light extraction efficiency. The UV bi-layer imprinting and lift-off processes were used to form the TiO2 nano-structure without any plasma etching process, which can lead to degradation of the electrical properties of the device. As a result, the light output power of the LED on the patterned sapphire substrate (PSS) with the TiO2 nano-structure was enhanced up to 12% compared to identical LED formed on the PSS without TiO2 nano-structure. No electrical degradation was observed for the patterned LED device.

A vertical light-emitting diode (LED) with a chip size of 500 × 500 µm2 was fabricated by the laser lift-off (LLO) process of an InGaN-based blue LED wafer. After the LLO process, photonic crystal patterns by UV nano-imprint lithography were formed on the n-GaN top layer of the vertical LED over the entire area with a diameter of 2 inches. As the result of n-GaN patterning, light output power of the vertical LED with photonic crystals was increased by up to 44% compared to that of the vertical LED without a photonic crystal at a driving current of 1000 mA.

The indium tin oxide (ITO) transparent electrode layer on green and blue light-emitting diodes (LEDs) was patterned with various-sized periodic hole arrays, size ranging from 300 nm to 380 nm, using thermal nanoimprint lithography and inductively coupled plasma (ICP) etching processes. The imprinted resin was used as a mask layer and etch resistance of the imprinted resin was adjusted in order to control the tapered and enlarged etch profile of the ITO layer, since the tapered etch profile can improve the light extraction efficiency of the LED by prominent scatterings. Photoluminescence intensity from InGaN multi-quantum wells for the green LED structure showed that up to 4.6 times stronger emission was exhibited with the patterned ITO electrode, compared to the identical sample with an un-patterned blanket ITO electrode layer. An electroluminescence (EL) intensity of a blue LED sample witha patterned ITO electrode layer was increased up to 23% compared to that of the identical sample with an un-patterned blanket ITO electrode layer.

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A micro- and nanoscale complex structure made of a high refractive index polymer (n = 2.08) was formed on the ITO electrode layer of an edge-emitting type GaN blue light-emitting diode (LED), in order to improve the photon extraction efficiency by suppressing total internal reflection of photons. The nanoimprint lithography process was used to form the micro- and nanoscale complex structures, using a polymer resin with dispersed TiO2 nano-particles as an imprint resin. Plasma processing, such as reactive ion etching, was used to form the micro- and nano-scale complex structure; thus, plasma-induced damage to the LED device can be avoided. Due to the high refractive index polymeric micro- and nanostructure on the ITO layer, the electroluminescence emission was increased up to 20%, compared to an identical LED that was grown on a patterned sapphire substrate to improve photon extraction efficiency.

The transition‐metal dichalcogenide HfS2 is a promising alternative semiconductor with adequate band gap and high carrier mobility. However, a controllable growth of continuous HfS2 films with selectivity for specific surfaces at a low temperature on a large scale has not been demonstrated yet. Herein, HfS2 films are grown at 100 °C by atomic layer deposition (ALD) based on the precursors tetrakis(dimethylamido)hafnium and H2S. In situ vibrational spectroscopy allows for the definition of the temperature range over which (Me2N)4Hf chemisorbs as one monolayer. In that range, sequential exposures of the solid surface with (Me2N)4Hf and H2S result in self‐limiting reactions that yield alternating surface termination with dimethylamide and thiol. Repeating the cycle grows smooth, continuous, stoichiometric films of thicknesses adjustable from angstroms to >100 nm, as demonstrated by spectroscopic ellipsometry, XRR, AFM, UV–vis and Raman spectroscopy, XPS, and TEM. The well‐defined surface chemistry enables one to deposit HfS2 selectively using, for example, patterns generated in molecular self‐assembled monolayers. This novel ALD reaction combines several attractive features necessary for integrating HfS2 into devices.