Molecular Layer Deposition Cycles Research Articles

Molecular layer deposition of conjugated microporous polymers (CMPs) thin films for fast molecular sieving

Conjugated microporous polymers (CMPs) have great potential in membrane separation for their intrinsic microporosity and outstanding stability. Unfortunately, most CMPs are insoluble and infusible, thus it is very challenging to prepare CMPs membranes through conventional strategies. Herein, we report the molecular layer deposition (MLD) strategy to synthesize CMP thin films and their outstanding molecular sieving performances as nanofiltration membranes. Thanks to the gas-phase self-limiting reactions between volatile monomers during MLD, defect-free and large-area CMP thin films are deposited on porous substrates. The thickness of the CMP films is precisely tuned by the repeating MLD cycle numbers, and 100 MLD cycles result in a CMP thin film with the thickness of ∼ 70 nm. The as-prepared composite membranes with the deposited MLD thin films as the selective layers exhibit superior molecular sieving properties with a permeance up to 134 L m-2h−1 bar−1, outperforming other CMP membranes. In addition, the perm-selectivity of CMP membranes can be easily tuned by changing MLD cycle numbers. We further demonstrate that, by optimizing the deposition process including selecting proper precursors, CMP thin films can be successfully MLD-deposited onto temperature-sensitive polymeric substrates with the size as large as 10 cm × 10 cm. This work shows the feasibility and great potential of MLD synthesis of CMP thin films, which opens new avenues not only for the synthesis of CMPs with highly controllable thickness, but also for the preparation of advanced membranes for diverse applications.

Synthesis of ultrathin heteroepitaxial 3C-SiC films by pyrolysis of molecular layer deposition polyamide films on Si

Polyamide films were grown on Si(111) using a molecular layer deposition (MLD) process with 1,2-ethylenediamine and trimesoyl chloride precursors at 120 °C. Synthesized polyamide films on Si(111) were then pyrolyzed in vacuum (10−7 Torr) to yield crystalline SiC thin films. High-resolution transmission electron microscope images of heat-treated samples showed the heteroepitaxial nature of the synthesized 3C-SiC (β-SiC) with respect to the Si(111) substrate. Raman, x-ray photoelectron spectroscopy, and x-ray diffraction analysis confirmed the formation of single-crystal SiC films. Samples pyrolyzed at 1300 °C showed defects attributed to Si sublimation. Formation of highly conformal SiC film after pyrolysis was demonstrated using Bosch-processed Si trenches. The thicknesses of 3C-SiC films obtained after pyrolysis were linearly dependent on the number of MLD cycles used to deposit polyamide films.

Molecular layer deposition for the fabrication of desalination membranes with tunable metrics

The recent advancement of semiconductor devices to the near-atomic scale necessitated the development of atomic layer processing methods, including molecular layer deposition (MLD). This gas-phase deposition technique creates semipermeable polymer films with precise control of composition and thickness. Herein, MLD was used to produce thin-film composite reverse osmosis membranes. Aromatic polyamide films as thin as 0.5 nm were applied to NF270 nanofiltration membranes using m-phenylenediamine and trimesoyl chloride. Within two molecular layers, desalination performance was affected. As film thickness increased to 15 nm (48 MLD cycles), performance progressed from nanofiltration to reverse osmosis metrics in terms of salt rejection and water permeance. With film thickness > 5 nm, rejection values exceeded a small sampling of commercial membranes. In all cases, a tradeoff between rejection and permeance was observed. Atomic force microscopy measurements indicate that MLD enhancement led to removal of small-scale roughness features and resulted in a root mean square roughness difference of <0.1 nm from the substrate. These initial MLD studies represent a novel processing approach that offers a potential pathway for the fabrication of membranes with finely tailored properties.

Molecular layer deposition of Nylon 2,6 polyamide polymer on flat and particle substrates in an isothermal enclosure containing a rotary reactor

Polyamide thin films, designated Nylon 2,6, were grown on flat and particle substrates using molecular layer deposition (MLD) in a custom-built isothermal enclosure containing a rotary reactor. The polyamide films were grown using sequential exposures of ethylene diamine and adipoyl chloride. The reactor and precursors were contained in a fiberglass oven to keep all reactor components at the same temperature. A growth rate of 4.0 Å/cycle at 67 °C was determined on flat substrates with ex situ x-ray reflectivity and spectroscopic ellipsometry. The temperature dependence of the Nylon 2,6 displayed a peak growth rate at 67 °C with decreasing growth rates above and below this temperature. X-ray photoelectron spectroscopy of the polyamide film on flat substrates also revealed an elemental composition consistent with the Nylon 2,6 polymer with a small amount of chlorine in the film. The isothermal reactor allowed MLD to be performed consistently on high surface area particles at low temperatures. Transmission electron microscopy (TEM) images showed growth of the Nylon 2,6 films on ZrO2, cellulose, and metformin particles that was consistent with the growth on witness wafers. The growth of the Nylon 2,6 films was also linear versus the number of MLD cycles. The TEM images displayed reproducible MLD growth on particles of varying size and composition. Fourier transform infrared spectroscopy and energy dispersive spectroscopy were consistent with the expected characteristics of the Nylon 2,6 polyamide film. Nylon 2,6 MLD should find application when low-temperature MLD is needed to coat thermally sensitive substrates such as organic films or pharmaceutical powders.

Amine-functionalized fumed silica for CO2 capture through particle molecular layer deposition

Solid adsorbent materials for CO2 capture have received increasing attention due to the high regenerative energy requirements and physical limitations of traditional liquid systems. Supported amines have become widely-researched materials due to their ambient adsorption capabilities and low regeneration temperatures. Here, Particle Molecular Layer Deposition (MLD) is introduced as a novel loading method for amine functionalization to improve the regeneration stability and adsorption capacity of supported amine sorbents. This paper confirms two MLD chemistries: (3-aminopropyl)triethoxysilane (APTES) and N1-(3-trimethoxysilylpropyl)diethylene triamine (TMPTA). Both precursors were deposited at 150 °C in a binary reaction with water. Adsorption capacity of the amine functional groups increased to ~0.005 mmol/m2 as the number of MLD cycles increased. Low sorbent regeneration temperatures and stable regeneration of active sites over 25 cycles were demonstrated by both the APTES and TMPTA functionalized sorbent. This is the first demonstration of an MLD process used to functionalize a sorbent for CO2 capture. This is also the first use of TMPTA for MLD.

Humidity-resistant gas sensors based on SnO2 nanowires coated with a porous alumina nanomembrane by molecular layer deposition

We report a novel route for enhancing the humidity resistance of SnO2 nanowires (NWs; widely used metal oxide semiconductor gas sensors) based on their coating with a humidity-resistant nanomembrane. A conformal thin film was deposited by Molecular Layer Deposition (MLD) on the SnO2 NWs using trimethylaluminum and ethylene glycol as precursors (100 MLD cycles), followed by oxidation in air at 400 °C. In conditions of increasing relative humidity, the SnO2 NW gas sensor coated with a microporous, 10-nm thick nanomembrane layer of converted alucone obtained by MLD and calcination showed a remarkable gas response compared with the pristine SnO2 NW gas sensor. This sensor was stable and displayed good recovery times in humid conditions (30 and 90 % of relative humidity). This work shows the benefits and the practical application of MLD-prepared nanomaterials. This original strategy applied to NW-based gas sensors paves the way for other complex 3D designs and different applications that require gas or ion selectivity, such as photocatalysts and biosensors, in humid atmosphere.

Area-selective molecular layer deposition of nylon 6,2 polyamide: Growth on carbon and inhibition on silica

In microelectronic or nanoelectronic manufacturing, pattern transfer by directional reactive ion etching (RIE) progressively erodes amorphous carbon (aC) hard masks. To maintain critical dimensions and tolerances of high-aspect-ratio device structures, new carbonaceous materials may be added repeatedly to replace the eroded aC hard mask. Such a mask repairing step during RIE needs self-aligning growth of organic materials. Area selectivity is required to deposit the organic material on the aC hard mask exclusively. Deposition on the dielectric or semiconductor device structures underlying the mask would complicate their precise etching or later cleaning. When ashing the aC hard mask, all-organic materials are preferable to organic-inorganic hybrid materials because they leave no residue. In this work, area-selective molecular layer deposition (MLD) was developed for the all-organic polyamide nylon 6,2. The monomer reactants for nylon 6,2 MLD were ethylene diamine and adipoyl chloride. Nylon 6,2 MLD was studied in the homogeneous, steady-state growth regime and during nucleation on various starting surfaces utilizing in situ spectroscopic ellipsometry. Area-selective MLD of nylon 6,2 was achieved on the “growth” carbon surface in the presence of silica by functionalizing aC via mild oxidation. In addition, a surface passivant was selectively attached to silica by using an amine-catalyzed coupling chemistry. The passivant inhibited the nylon 6,2 MLD on the “nongrowth” silica surface. A single passivation pretreatment was sufficient to restrict the MLD on the silica surface. The passivant, however, did not substantially impact the MLD nucleation and growth on the aC surface. This strategy yielded area selectivity with exceptionally high quality and over a wide range of MLD cycles. The area-selective MLD of nylon 6,2 was further applied on industrial test features with aC patterns masking trenches in silica. This demonstration illustrated the capability of area-selective MLD to repair RIE-eroded aC hard masks and to maintain the critical dimension.

Molecular layer deposition (MLD) modified SSZ-13 membrane for greatly enhanced H2 separation

Zeolite membranes with high thermal stability and well-fined pores are attractive for gas separation. However, the defects are almost inevitable in zeolite membranes. Moreover, fine-tuning zeolitic pores for precise molecular separation is challenging. In this study, molecular layer deposition (MLD) was employed to deposit ultrathin microporous coating on SSZ-13 zeolite membrane. The MLD modified SSZ-13 composite membrane was highly selective for H2 separation. With optimized MLD cycles, H2/N2 and H2/CH4 ideal selectivities as high as 35.6 and 427, respectively, were obtained, in strong contrast with approximately 5 for base SSZ-13 membrane. These results suggest that MLD is a very promising technology to precisely modify the pore size of zeolite membranes, while minimizing flow through non-selective defects, for gas separation.

Tuning the Ion-Selectivity of Thin-Film Composite Nanofiltration Membranes by Molecular Layer Deposition of Alucone.

This work addresses a key challenge of tailoring the ion selectivity of a thin-film composite nanofiltration membrane to a specific application, such as water softening, without altering the water permeability. We modified the active surface of a commercial NF270 membrane by molecular layer deposition (MLD) of ethylene glycol-Al (EG-alucone). With increasing deposition cycles, we found that the MLD precursors first infiltrated and deposited in the active layer of NF270, then inflated the active layer, and finally deposited on the surface as a distinct EG-alucone layer. The deposition process changed the morphology of the membrane active layer and decreased the overall density of its fixed negative charge by embedding the positively charged EG-alucone. Filtration experiments revealed that these modifications affected the ion separation properties of the membrane without significantly hindering the water permeability. Specifically, the permeation of Na+ increased relative to that of Mg2+, as indicated by the permselectivity of Na+ salts over Mg2+ salts. The changes in permselectivities with an increasing number of MLD cycles were rationalized using the dielectric, steric, and electrostatic ion exclusion mechanisms, which are related to the membrane material, pore size, and fixed charge, respectively. These relations open a path for the rational design of nanofiltration membranes with tailored selectivity by tuning the properties of the MLD layer. Filtration results of natural brackish groundwater using the MLD modified membranes agreed with the single salt experiments. As a result, water hardness was 26% lower for the permeate obtained using the MLD-modified membranes, which were found stable even during a 24 h filtration run. These results highlight the practical potential of this approach in enhancing water softening efficiency.

Tailoring TiO2 membranes for nanofiltration and tight ultrafiltration by leveraging molecular layer deposition and crystallization

As an advanced gas phase deposition technique, molecular layer deposition (MLD) has recently emerged as a precisely controllable method to fabricate organic-inorganic hybrid materials such as metalcones and hybrid films. Porous structures can be prepared by thermally removing the organic constituents of the metalcones deposited by MLD. Herein, we revealed that there is a crystallization-induced volume shrinkage during thermal treatment of metalcone films. By taking advantage of both the chemical degradation of organic moieties of metalcone films and the crystallization-induced volume shrinkage, we built microporous TiO2 layers on porous ceramic substrates and obtained nanofiltration and tight ultrafiltration membranes with tunable molecular-weight-cut-off (MWCO) in the range between 630 Da and 3050 Da. Firstly, 50 MLD cycles of titanicone (TiEG) were deposited on the near-surface of plate ceramic ultrafiltration membranes to achieve a compact layer, which was then subjected to calcination at different temperatures to remove the organic constituents. The bare membrane with a water permeance of ∼130 L m−2 h−1 bar−1 and MWCO of ∼63 kDa was upgraded from ultrafiltration to nanofiltration with ∼7 L m−2 h−1 bar−1 permeance and ∼630 Da MWCO after MLD and calcination at 250 °C. Moreover, as the microporous TiO2 was transformed from amorphous to crystalline with rising calcination temperatures, there was higher volume shrinkage and larger effective pore sizes. Consequently, both water permeance and MWCOs of the membranes were increased. For instance, the membranes after calcination at 400 °C showed a tight ultrafiltration performance of ∼30 L m−2 h−1 bar−1 permeance and ∼3050 Da MWCO. This work provides a simple and effective way to fabricate ceramic membranes with tunable performances between ultrafiltration, tight ultrafiltration, and nanofiltration.

Stabilizing interface between Li10SnP2S12 and Li metal by molecular layer deposition

Safe and high-energy-density lithium rechargeable batteries are urgently required for vehicle electrification and grid energy storage. All-solid-state lithium metal batteries (ASSLMBs) are regarded as a good choice to meet these stringent requirements. However, interfacial instability between Li metal and solid-state sulfide electrolytes (SEs) and lithium dendrite formation are main challenges to be overcome. In this work, molecular layer deposition (MLD) is employed for the first time to develop an inorganic-organic hybrid interlayer (alucone) at the interface between the Li metal and SEs. It is found that the alucone layer can serve as an artificial solid electrolyte interphase (SEI). As a result, interfacial reactions between Li and SEs are significantly suppressed by intrinsically blocking electron transfer at the interface. In addition, lithium dendrites are also suppressed. Coupled with a LiCoO2 cathode, ASSLMBs with 30 MLD cycles of alucone on Li metal exhibit a high initial capacity of 120 mAh g−1 and can retain a capacity of 60 mAh g−1 after 150 cycles. This work exemplifies the use of MLD to stabilize the interface between SEs and Li metal for ASSLMBs.

Spatial molecular layer deposition of polyamide thin films on flexible polymer substrates using a rotating cylinder reactor

Polyamide thin films were rapidly grown using spatial molecular layer deposition (MLD) in a rotating cylinder reactor. The polyamide MLD films were coated on flexible metalized polyethylene terephthalate substrates using sequential exposures of trimesoyl chloride (TMC) and m-phenylenediamine (mPD). The rotating cylinder reactor was housed in a custom oven enclosure that maintained a constant temperature of 115 °C. One MLD cycle (TMC/mPD) was performed per rotation of the cylinder. Polyamide growth rates of 4.5 Å/cycle or 90 Å/min were observed at a slow rotation speed of 20 revolutions per minute (RPM) at a substrate speed of 0.33 m/s. Growth rates of 2.27 Å/cycle or 477 Å/min were measured at higher rotation speeds of 210 RPM at substrate speeds of 3.5 m/s. The polyamide film thicknesses were uniform over the substrate widths as large as ∼16.5 cm. The polyamide MLD surface chemistry was also self-limiting. Constant polyamide growth rate per cycle was measured at larger TMC and mPD exposures. In addition, infrared analysis and thermal annealing studies confirmed the chemical identity of the polyamide films. With four MLD cycles per rotation of the rotating cylinder, spatial MLD should be able to obtain polymer growth rates of &amp;gt;1900 Å/min at a rotation speed of 210 RPM. These rapid growth rates are much higher than the growth rates that can be obtained in temporal MLD reactors. The spatial MLD of polyamide films has many possible applications including the deposition of ultrathin reverse osmosis membranes for water desalination.

Functionalization of multiwalled carbon nanotubes with uniform polyurea coatings by molecular layer deposition

In this study, we demonstrate a flexible method for functionalizing multiwalled carbon nanotubes (MWCNTs) with polyurea (PU) coatings using molecular layer deposition (MLD). Uniform and conformal PU films can be deposited on the surface of pristine MWCNTs without any surface treatment. The PU shell thickness and wrapping amount are precisely tunable by changing the number of MLD cycles. The present MLD functionalizing treatment provides better dispersion of the MWCNTs in highly polar solvents such as N,N-dimethylformamide, dimethyl sulfoxide, and 1-methyl-2-pyrrolidinone. Furthermore, the PU layers improve the compatibility between MWCNTs and the polyurethane matrix. Significant increases in tensile strength and modulus are obtained, resulting in greatly enhanced mechanical properties of PU-functionalized MWCNT/polyurethane composites.

Growth and properties of hafnicone and HfO(2)/hafnicone nanolaminate and alloy films using molecular layer deposition techniques.

Molecular layer deposition (MLD) of the hafnium alkoxide polymer known as "hafnicone" was grown using sequential exposures of tetrakis(dimethylamido) hafnium (TDMAH) and ethylene glycol (EG) as the reactants. In situ quartz crystal microbalance (QCM) experiments demonstrated self-limiting reactions and linear growth versus the number of TDMAH/EG reaction cycles. Ex situ X-ray reflectivity (XRR) analysis confirmed linear growth and measured the density of the hafnicone films. The hafnicone growth rates were temperature-dependent and decreased from 1.2 Å per cycle at 105 °C to 0.4 Å per cycle at 205 °C. The measured density was ∼3.0 g/cm(3) for the hafnicone films at all temperatures. Transmission electron microscopy images revealed very uniform and conformal hafnicone films. The XRR studies also showed that the hafnicone films were very stable with time. Nanoindentation measurements determined that the elastic modulus and hardness of the hafnicone films were 47 ± 2 and 2.6 ± 0.2 GPa, respectively. HfO2/hafnicone nanolaminate films also were fabricated using HfO2 atomic layer deposition (ALD) and hafnicone MLD at 145 °C. The in situ QCM measurements revealed that HfO2 ALD nucleation on the hafnicone MLD surface required at least 18 TDMAH/H2O cycles. Hafnicone alloys were also fabricated by combining HfO2 ALD and hafnicone MLD at 145 °C. The composition of the hafnicone alloy was varied by adjusting the relative number of TDMAH/H2O ALD cycles and TDMAH/EG MLD cycles in the reaction sequence. The electron density changed continuously from 8.2 × 10(23) e(-)/cm(3) for pure hafnicone MLD films to 2.4 × 10(24) e(-)/cm(3) for pure HfO2 ALD films. These hafnicone films and the HfO2/hafnicone nanolaminates and alloys may be useful for flexible thin-film devices.

Molecular Layer Deposition of Zircone and ZrO2/Zircone Alloy Films: Growth and Properties

AbstractHybrid organic/inorganic polymer films based on zirconium are grown using molecular layer deposition (MLD) techniques. The zirconium alkoxide films, known as “zircones”, are grown using sequential exposures of zirconium tert‐butoxide (ZTB) and ethylene glycol (EG) as the reactants at temperatures from 105 to 195°C. In‐situ quartz crystal microbalance (QCM) and ex‐situ X‐ray reflectivity (XRR) experiments confirm linear growth versus the number of reaction cycles. The growth rates decrease versus temperature from 1.6 Å per cycle at 105°C to 0.3 Å per cycle at 195°C. The measured density is ∼2.17 g cm−3 for all the growth temperatures. Transmission electron microscopy (TEM) images reveal very uniform and conformal zircone films. ZrO2/zircone alloys are also fabricated by combining ZrO2 atomic layer deposition (ALD) and zircone MLD at 145°C. The composition of the ZrO2/zircone alloy is varied by adjusting the relative number of ZrO2 ALD and zircone MLD cycles in the reaction sequence. The ZrO2/zircone alloys display varying density, refractive index, elastic modulus, and hardness. The refractive index and elastic modulus change progressively from n = 1.63 and E= 27 ± 0.6 GPa for pure zircone MLD films, to n = 1.86 and E= 97 ± 5 GPa for pure ZrO2 ALD films, respectively. In capacitor structures, the zircone films display low leakage currents and a dielectric constant of ∼6.7. The zircone films are also utilized as the dielectric layer in pentacene‐based thin film transistors (TFTs), which display a high field effect mobility of 2.11 cm2 V−1 s−1 operating at −3 V with an on/off current ratio of ∼103. The zircone and ZrO2/zircone alloy films provide a new class of hybrid organic/inorganic polymer films for many functional film applications.

Critical tensile strain and water vapor transmission rate for nanolaminate films grown using Al2O3 atomic layer deposition and alucone molecular layer deposition

Critical tensile strains (CTSs) and water vapor transmission rates (WVTRs) were measured for nanolaminate films grown on polyimide substrates using Al2O3 atomic layer deposition (ALD) and alucone molecular layer deposition (MLD). Nanolaminate composition was controlled by varying the ratio of ALD:MLD cycles during film growth. For ∼100 nm film thicknesses, the CTS obtained its highest value of ∼1.0% for the 3:1 nanolaminate. The WVTR decreased dramatically versus nanolaminate composition and reached the measurement sensitivity limit at WVTR ∼1 × 10−4 g/(m2day) for the 7:2, 5:1, and 6:1 nanolaminates. The ALD:MLD nanolaminates may be useful as flexible gas/vapor diffusion barriers on polymers.

Highly Conductive and Transparent Hybrid Organic–Inorganic Zincone Thin Films Using Atomic and Molecular Layer Deposition

Highly conducting and transparent hybrid organic–inorganic thin films were grown using atomic layer deposition (ALD) and molecular layer deposition (MLD) techniques. The conducting films were grown at 150 °C by combining ZnO ALD and zincone MLD processes. ZnO ALD was performed using diethylzinc (DEZ) and water (H2O). Zincone MLD was performed using DEZ and hydroquinone (HQ). The ALD:MLD alloys were deposited by controlling the relative number of ALD and MLD cycles in the reaction sequence. The growth of the ALD:MLD alloys was examined using in situ quartz crystal microbalance and Fourier transform infrared spectroscopy studies. The surface reactions during alloy growth were self-limiting, and the ALD and MLD reaction sequences produced linear growth rates. The alloys exhibited exceptional conductivity relative to ZnO ALD films grown at 150 °C. The highest conductivities were obtained from alloys with ALD:MLD cycle ratios of 1:1 and 2:2. The 1:1 and 2:2 alloy films yielded conductivities of 116 and 170 S/c...

Alucone Alloys with Tunable Properties Using Alucone Molecular Layer Deposition and Al2O3 Atomic Layer Deposition

Ultrathin and conformal hybrid organic–inorganic thin films can be deposited by molecular layer deposition (MLD) techniques. By combining the hybrid organic–inorganic MLD process with an inorganic atomic layer deposition (ALD) process, ALD/MLD alloy films can be deposited that have an adjustable organic–inorganic composition. These alloys have tunable properties that may be useful for designing various functional films. In this study, alucone MLD using trimethylaluminum (TMA) and ethylene glycol (EG) was employed together with Al2O3 ALD using TMA and H2O to deposit alucone alloys at 135 °C. The surface species and film growth were examined using in situ Fourier transform infrared spectroscopy. The mass gain for each reactant exposure during film growth was also monitored using an in situ quartz crystal microbalance (QCM) in a viscous flow reactor. The composition of the alucone alloy was varied by adjusting the relative number of ALD and MLD cycles in the reaction sequence. Alucone alloys were grown using relative numbers of ALD and MLD cycles varying from 1:3 to 6:1 (TMA/H2O:TMA/EG). These alucone alloys displayed varying density, refractive index, elastic modulus, and hardness. The density and refractive index changed from 1.6 g/cm3 and n = 1.45 for pure alucone to 3.0 g/cm3 and n = 1.64 for pure Al2O3, respectively. The elastic modulus and hardness varied from 21 ± 8 GPa and 1.0 ± 0.1 GPa for pure alucone to 198 ± 8 GPa and 13.0 ± 0.2 GPa for pure Al2O3, respectively. These results demonstrate the potential of ALD/MLD alloy films to provide tunable properties for many functional film applications.

Atomic/molecular layer deposited thin-film alloys of Ti-4,4′-oxydianiline hybrid–TiO2 with tunable properties

By combining atomic layer deposition (ALD) and molecular layer deposition (MLD) thin-film techniques, the latter being a variant of the former in which organic precursors are used, it is possible to deposit thin films containing precisely controlled portions of inorganic and organic constituents. This in turn enables the adjustment of material properties by changing the number of ALD and MLD cycles applied during the deposition. In this work, the properties of such thin-film "alloys" prepared by varying the portions of Ti-4,4'-oxydianiline (Ti-ODA) inorganic-organic hybrid and TiO(2) in the structure were investigated. The films were deposited at 280 °C using TiCl(4) and water as precursors for TiO(2), and TiCl(4) and ODA for the Ti-ODA hybrid. The results demonstrate excellent tunability of the film properties such as degree of crystallinity, roughness, refractive index, and hardness depending on the relative number of TiO(2) and Ti-ODA cycles employed.

(Invited) Molecular Layer Deposition of Flexible, Transparent and Conductive Hybrid Organic-Inorganic Thin Films

Hybrid organic-inorganic thin film alloys were fabricated by molecular layer deposition (MLD) and atomic layer deposition (ALD) methods using diethyl zinc (DEZ), hydroquinone (HQ), and water (H2O). Sequential exposures of DEZ & HQ for zincone MLD and DEZ & H2O for ZnO ALD led to the linear growth of zincone alloy films. The alloy film composition could be varied by changing the number of MLD cycles and ALD cycles per reactant sequence. The alloy films were found to be highly conductive. Zincone alloys grown with MLD:ALD cycle ratios of 1:1 and 2:2 displayed sheet resistivities in the 10-3Ω cm range. These sheet resistivities were substantially lower than the sheet resistivity for ZnO ALD films. These alloys films may be useful as flexible, transparent and conducting coatings.