Oxide Atomic Layer Deposition Research Articles

Improvement of Mechanical Characteristics on Ultra-High Molecular Weight Polyethylene Surface through Zinc Oxide Atomic Layer Deposition Film

Wear failures in ultra-high molecular weight polyethylene (UHMWPE) compartments are known to limit the life of a joint implant. In this study, we applied atomic layer deposition (ALD) technique to produce wear-resistant zinc oxide (ZnO) films to improve mechanical and wear characteristics on the surface of UHMWPE. Organic material layers in molecular units were mixed with ALD ZnO films to minimize surface cracks through a molecular layer deposition (MLD) technique. We aimed to examine (1) the effect of organic layers on minimizing surface cracks and (2) the mechanical properties of ZnO and inorganic/organic hybrid films. We prepared UHMWPE samples with pure ZnO and five different hybrid films with ZnO to organic layer ratios of 1 : 1, 2 : 1, 3 : 1, 4 : 1, and 5 : 1. Surface cracks were observed by using a field-emission scanning electron microscope. Hardness and elastic modulus of an ALD-coated UHMWPE were measured by nano-indentation examinations. Severe cracks were found in the samples with pure ZnO films. However, no cracks were found in the samples with all hybrid films except the samples with a ZnO to organic layer ratio of 5 : 1. The hardness and elastic modulus of the samples with pure ZnO and hybrid films significantly increased compared to those of the native UHMWPE. The hardness to elastic modulus ratios, indicating the wear resistance, increased over 50% for all films compared to the values of native UHMWPE. These results suggested that ALD ceramic coatings with organic layers may become a potential solution for realizing a wear-resistant protection coating for the polymer compartment of joint prostheses.

Atomic layer deposition of conductive and semiconductive oxides

Conductive and semiconductive oxides constitute a class of materials of which the electrical conductivity and optical transparency can be modulated through material design (e.g., doping and alloying) and external influences (e.g., gating in a transistor or gas exposure in a gas sensor). These (semi)conductive oxides, often categorized as amorphous oxide semiconductors or transparent conductive oxides, have, therefore, been commonplace in, for example, solar cells and displays, as well as in an increasing variety of other applications including memory, logic, photonics, and sensing. Among the various deposition techniques, the use of atomic layer deposition (ALD) has been gaining in popularity in recent years. Specifically since the early 2000s, many ALD processes for doped and compound conductive metal oxides have been developed. The interest in such oxides prepared by ALD can most likely be attributed to the distinct merits of ALD, such as low-temperature processing, excellent uniformity and conformality, and accurate control over the doping level and composition. Moreover, as device dimensions shrink the need for high-quality, ultrathin materials becomes ever more important. These merits of ALD stem directly from the self-limiting nature of the surface chemistry that drives the ALD growth. On the other hand, the strong role that surface chemistry has in the growth mechanism brings in many intricacies, and detailed understanding of these aspects has been vital for the development of high-quality doped and compound oxides by ALD. Examples of growth effects that can occur during ALD of compound oxides include growth delays, clustering of dopants, and interruption of grain growth by doping. Such effects often need to be accounted for or mitigated, while on the other hand, there are also clear cases where such growth effects can be leveraged to achieve enhanced or new functionality. In this review paper, an overview of the library of ALD processes that has emerged is presented. Available precursor chemistries, dopants as well as achieved film properties—most notably the carrier densities and (field-effect) mobilities of the films—are presented. A selection of important ALD effects that can occur during the deposition of doped and compound conductive oxides is showcased, and their effect on the optical and electrical properties are highlighted. Mitigation and improvement strategies for negative growth effects are presented. This is done through case studies that clearly illustrate these effects, drawing both from literature and from our own recent work.

High-Quality SiO2/O-Terminated Diamond Interface: Band-Gap, Band-Offset and Interfacial Chemistry.

Silicon oxide atomic layer deposition synthesis development over the last few years has open the route to its use as a dielectric within diamond electronics. Its great band-gap makes it a promising material for the fabrication of diamond-metal-oxide field effects transistor gates. Having a sufficiently high barrier both for holes and electrons is mandatory to work in accumulation and inversion regimes without leakage currents, and no other oxide can fulfil this requisite due to the wide diamond band-gap. In this work, the heterojunction of atomic-layer-deposited silicon oxide and (100)-oriented p-type oxygen-terminated diamond is studied using scanning transmission electron microscopy in its energy loss spectroscopy mode and X-ray photoelectron spectroscopy. The amorphous phase of silicon oxide was successfully synthesized with a homogeneous band-gap of 9.4 eV. The interface between the oxide and diamond consisted mainly of single- and double-carbon-oxygen bonds with a low density of interface states and a straddling band setting with a 2.0 eV valence band-offset and 1.9 eV conduction band-offset.

Growth of Multiple Island Layers during Iron Oxide Atomic Layer Deposition: An Electron Microscopy and Spectroscopic Ellipsometry Investigation

Growth of Multiple Island Layers during Iron Oxide Atomic Layer Deposition: An Electron Microscopy and Spectroscopic Ellipsometry Investigation

Atomic layer deposition modified PIM-1 membranes for improved CO2 separation: A comparative study on the microstructure-performance relationships

The use of atomic layer deposition (ALD) technology has recently been extended to membrane-based gas separation, whereas how the ALD of metal oxides can tailor the membrane microporosity, and the contribution of the interactions between ALD-grown metal oxide clusters and gas molecules to the resultant gas separation performance, remain largely unclear. Here, a comparative study was performed by individually confining three different metal oxides, including Al2O3, ZnO, and TiO2, to the near-surface region of polymers of intrinsic microporosity (PIM-1) membranes in an attempt to clarify the relationships between microstructural properties and CO2 separation performance. Based on experimental characterizations and density functional theory (DFT) calculations, it is suggested that ALD of metal oxides on PIM-1 membranes can not only effectively narrow the micropore sizes, but also enable enhancement of the solubility of CO2 molecules. Meanwhile, gas permeation results revealed that the CO2 permeation behavior through either Al2O3- or ZnO-modified membranes is diffusion-dominated, while that of the TiO2-modified membranes is sorption-dominated, primarily due to the distinct differences in the loading amount of metal oxides and their interaction strength with the CO2 molecules. As a result, the TiO2-modified membranes achieved a significant increase in the CO2 permeability as the ALD cycle numbers increased together with no sacrifice of CO2/N2 and CO2/CH4 selectivities. This study is expected to lend important insight to the development of ALD-modified membranes for efficient CO2 separation.

(Invited) ALD Coatings for Li-Ion Battery and All-Solid-State Battery Applications

Lithium-ion batteries (LIBs) are essential for modern life, and their improvement is crucial for the more widespread adoption of electric vehicles.[1] Layered lithium transition metal oxides, such as LiNixCoyMnzO2 (often referred to as NCM or NMC), are among the most widely used cathode active materials (CAMs) for automotive applications, owing to their technological maturity and high energy density. However, they typically require a surface coating for stabilizing interfaces, both in liquid-electrolyte based LIBs and in solid-state battery (SSB) environments. For the preparation of protective CAM coatings, atomic layer deposition (ALD) stands out with its ability to produce conformal films on complex substrates.This presentation encompasses several examples of successful improvements in cycling performance of Ni-rich NCM CAMs in LIBs and SSBs by ALD of binary oxides. The low-temperature deposition of AlxOy onto ready-to-use cathode sheets will be discussed.[2] ALD or ALD-related surface protection enables increased stability by suppressing detrimental surface corrosion and metal leaching (side reactions) in LIBs.[2,3] Moreover, we report about the application of ALD coatings to Ni-rich NCM CAMs in SSBs with lithium thiophosphate solid electrolytes. Specifically, the effect that both HfO2 and ZrO2 have on the cell cyclability will be shown, with emphasis placed on the role of post annealing.[4] [1] Goodenough et al. J. Am. Chem. Soc. 2013, 135, 1167.[2] Neudeck et al. Sci. Rep. 2019, 9, 5328.[3] Neudeck et al. Chem. Commun. 2019, 55, 2174.[4] Kitsche et al. ACS Appl. Energy Mater. 2021, 4, 7338.

Characterization of the Local Atomic Structure of ALD Coated Interfaces

To accelerate technological innovations using atomic layer deposition (ALD) coatings, we need to establish better understanding of structure-property relationships for ALD films. Historically, the ALD community has had difficulty connecting the atomic structure of ALD films with their performance, largely because of the significant challenge in determining the atomic-scale structure of ultrathin ALD films that are often amorphous, polycrystalline, or defective. In this work, we describe a series of recent efforts that collectively aim to improve understanding of the atomic structure of ALD coatings and inform structure-property understanding. These efforts employ experimental measurements including (a) inert-transfer XPS, (b) in-situ synchrotron high energy X-ray diffraction, and (c) cryogenic electron diffraction. Of particular focus in this talk is the use of X-ray and electron diffraction measurements in combination with pair distribution function (PDF) analysis and reverse Monte Carlo (RMC) structural modeling. We describe a newly developed approach employing alternating RMC and molecular statics steps (RMC-MS) that improves the physical accuracy of model structures derived from experimental diffraction data with minimal additional computational cost over conventional RMC modeling. We also describe efforts using localized cryogenic electron diffraction and PDF analysis (cryo-ePDF) with a ≤ 5 nm spot size to measure atomic structure at ALD interfaces. Together, these advances allow us to quantify differences in the atomic structure as a function of position through the depth of ALD films. A simple two-phase model comprised of bulk and interfacial layers with distinct atomic structure features is consistent with our measurements for both aluminum oxide and zinc oxide ALD coatings. The approaches we report yield atomic structure models that can be used to inform computational studies of the properties if ALD films and will aid in the selection and modification of ALD coating chemistries to address technological needs.

Atomic layer deposition of oxide coatings on porous metal and polymer structures fabricated by additive manufacturing methods (laser-based powder bed fusion, material extrusion, material jetting)

Complex porous 316 L stainless steel, Ti-6Al-4V, Ti-6Al-7Nb, ULTEM™ 1010 and MED610™ polymer structures were produced with additive manufacturing methods. The structures were surface functionalized by atomic layer deposition of titanium, zinc and zirconium oxide coatings with a thickness between 14 and 43 nm. Deep and narrow structures with aspect ratios >10 could be coated. Titanium oxide films are mostly amorphous when plasma-assisted deposition is used and contain nanocrystalline anatase when deposited by thermal atomic layer deposition. The deposited titanium oxide grains ranged in size from ∼20 to 60 nm. In interior parts of the fractured porous polymer model structures with pore sizes of 1–2 mm, both thermal and plasma-assisted titanium oxide thin films and partly delamination were detected. X-ray photoelectron spectroscopy analysis revealed almost stoichiometric composition and dominance of the Ti (IV) oxidation state at a 250 °C deposition temperature. Zinc oxide coatings in porous polymer model structures partly delaminate as well, while adhesion and homogeneity is higher for printed Ti-6Al-7Nb lattice structures with a 0.5-mm mesh size. Zirconium oxide coatings on Ti-6Al-4V lattice structures with a 0.8-mm mesh size are comparable to zinc oxide coatings but are mostly crystalline. This is attributed to the relatively high, 300 °C deposition temperature. The findings demonstrate potential but also limitations of combined additive manufacturing and atomic layer deposition for medicine and energy production applications. In addition, the results confirm previous studies that metallic and polymeric substrate materials and process conditions strongly influence the coating structure and composition, and individual development of each intended application is required.

Atomic Layer Deposition of Metal Oxides and Chalcogenides for High Performance Transistors.

Atomic layer deposition (ALD) is a deposition technique well‐suited to produce high‐quality thin film materials at the nanoscale for applications in transistors. This review comprehensively describes the latest developments in ALD of metal oxides (MOs) and chalcogenides with tunable bandgaps, compositions, and nanostructures for the fabrication of high‐performance field‐effect transistors. By ALD various n‐type and p‐type MOs, including binary and multinary semiconductors, can be deposited and applied as channel materials, transparent electrodes, or electrode interlayers for improving charge‐transport and switching properties of transistors. On the other hand, MO insulators by ALD are applied as dielectrics or protecting/encapsulating layers for enhancing device performance and stability. Metal chalcogenide semiconductors and their heterostructures made by ALD have shown great promise as novel building blocks to fabricate single channel or heterojunction materials in transistors. By correlating the device performance to the structural and chemical properties of the ALD materials, clear structure–property relations can be proposed, which can help to design better‐performing transistors. Finally, a brief concluding remark on these ALD materials and devices is presented, with insights into upcoming opportunities and challenges for future electronics and integrated applications.

A Tandem Interfaced (Ni3 S2 -MoS2 )@TiO2 Composite Fabricated by Atomic Layer Deposition as Efficient HER Electrocatalyst.

Reported herein is a highly active and durable hydrogen evolution reaction (HER) electrocatalyst, which is constructed following a tandem interface strategy and functional in alkaline and even neutral medium (pH ≈ 7). The ternary composite material, consisting of conductive nickel foam (NF) substrate, Ni3 S2 -MoS2 heterostructure, and TiO2 coating, is synthesized by the hydrothermal method and atomic layer deposition (ALD) technique. Representative results include: (1) versatile characterizations confirm the proposed composite structure and strong electronic interactions among comprised sulfide and oxide species; (2) the material outperforms commercial Pt/C by recording an overpotential of 115mV and a Tafel slope of 67mV dec-1 under neutral conditions. A long-term stability in alkaline electrolytes up to 200 h and impressive overall water splitting behavior (1.56V @ 10mA cm-2 ) are documented; (3) implementation of ALD oxide tandem layer is crucial to realize the design concept with superior HER performance by modulating a variety of heterointerface and intermediates electronic structure.

Characterization of Interface and Bulk Traps in Ultrathin Atomic Layer-Deposited Oxide Semiconductor MOS Capacitors With HfO2/In2O3 Gate Stack by C-V and Conductance Method

Oxide semiconductors have attracted revived interest for complementary metal–oxide–semiconductor (CMOS) back-end-of-line (BEOL) compatible devices for monolithic 3-dimensional (3D) integration. To obtain a high-quality oxide/semiconductor interface and bulk semiconductor, it is critical to enhance the performance of oxide semiconductor transistors. Atomic layer-deposited (ALD) indium oxide (In2O3) has been reported with superior performance such as high drive current, high mobility, steep subthreshold slope, and ultrathin channel. In this work, the interface and bulk traps in the MOS gate stack of ALD In2O3 transistors are systematically studied by using the C–V and conductance method. A low EOT of 0.93 nm is achieved directly from the accumulation capacitance in C–V measurement, indicating a high-quality gate oxide and oxide/semiconductor interface. Defects in bulk In2O3 with energy levels in the subgap are confirmed to be responsible for the conductance peak in GP/ω versus ω curves by TCAD simulation of C–V and G–V characteristics. A high n-type doping of 1×1020/cm3 is extracted from C–V measurement. A high subgap density of states (DOS) of 3.3×1020 cm−3 eV−1 is achieved using the conductance method, which contributes to the high n-type doping and high electron density. The high n-type doping further confirms the capability of channel thickness scaling because the charge neutrality level aligns deeply inside the conduction band.

Impact of interlayer insulator formation methods on HfOx ferroelectricity in the metal–ferroelectric–insulator–semiconductor stack

It has been reported that the HfOx-based metal–ferroelectric–insulator–semiconductor (MFIS) stack is one of the most feasible structures for memory applications in ferroelectric devices. In addition, in MFIS stacks, the formation of a high-quality thin insulator is considered to be a crucial process, because it determines the device performance and reliability. In this study, the effects of different SiO2 thin interfacial layers (ILs) formed by chemical oxidation and atomic layer deposition (ALD) on the ferroelectricity of HfOx were investigated in MFIS stacks. Notably, the IL formation method affected the crystallization temperature of HfOx ferroelectricity. In particular, the chemical oxide IL sample was sufficiently crystallized only at an RTA temperature greater than 800 °C, whereas the ALD oxide IL sample began to undergo a complete ferroelectric phase transition from a low temperature (600 °C). The x-ray analysis verified that the IL formation method affected the initial film state of the HfOx layer by modulating the Hf-O bonding states, resulting in a different temperature dependence for ferroelectricity formation during the subsequent crystallization annealing stage. Consequently, it was confirmed that stable polarization (2Pr > 30 μC/cm2) could be obtained over a wide temperature range (600–800 °C) through IL material engineering; this could facilitate the integration of HfOx-based ferroelectric devices in terms of the heat budget and the application of ferroelectric devices as commercial devices.

Surface Engineering Suppresses the Failure of Biphasic Sodium Layered Cathode for High Performance Sodium‐Ion Batteries

AbstractIn the process of upgrading energy storage structures, sodium‐ion batteries (SIBs) are regarded as the most promising candidates for large‐scale grid storage systems. However, the difficulty in further improving their specific capacity and lifespan has become a major obstacle to promoting extensive application. Herein, by optimizing synthesis conditions, a biphasic‐Na2/3Ni1/3Mn2/3O2 cathode that exhibits an ultrahigh capacity of ≈200 mAh g‐1 without the involvement of anion redox reactions is successfully synthesized. Nevertheless, there is significant electrochemical performance degradation because of failure at the cathode‐electrolyte interface as revealed by comprehensive analyses. Further in‐depth research proves that the surface side reactions that occur at high operating voltages and the transition metal dissolution that occurs in low voltage are the root causes of electrode surface failure. Therefore, the metal oxide atomic layer deposition (ALD) protective layer is deliberately chosen to suppress such failures. The coating effectively blocks corrosion of the cathode material by the electrolyte and successfully anchors the transition metal ions on the particle surface. As a result, the cycle stability and rate performance of the electrode are improved considerably. This surface engineering strategy could provide concepts with broad applicability for suppressing the failure of sodium layered cathodes.

Selective-Area, Water-Free Atomic Layer Deposition of Metal Oxides on Graphene Defects.

Passivating defective regions on monolayer graphene with metal oxides remains an active area of research for graphene device integration. To effectively passivate these regions, a water-free atomic layer deposition (ALD) recipe was developed and yielded selective-area ALD (sa-ALD) of mixed-metal oxides onto line defects in monolayer graphene. The anisotropically deposited film targeted high-energy defect sites that were formed during synthesis or transfer of the graphene layer. The passivating layer exceeded 10 nm thickness with minimal deposition onto the basal plane of graphene. The mixed-metal oxide film was of comparable quality to films deposited using nonselective water-based ALD methods, as shown by X-ray photoelectron spectroscopy. The development of sa-ALD techniques to target defect regions on the graphene sheet, while keeping the basal plane intact, will provide a new mechanism to passivate graphene defects and modify the electronic and physical properties of graphene.

Extended Barrier Lifetime of Partially Cracked Organic/Inorganic Multilayers for Compliant Implantable Electronics

Flexible and soft bioelectronics display conflicting demands on miniaturization, compliance, and reliability. Here, the authors investigate the design and performance of thin encapsulation multilayers against hermeticity and mechanical integrity. Partially cracked organic/inorganic multilayer coatings are demonstrated to display surprisingly year-long hermetic lifetime under demanding mechanical and environmental loading. The thin hermetic encapsulation is grown in a single process chamber as a continuous multilayer with dyads of atomic layer deposited (ALD) Al2 O3 -TiO2 and chemical vapor deposited Parylene C films with strong interlayer adhesion. Upon tensile loading, tortuous diffusion pathways defined along channel cracks in the ALD oxide films and through tough Parylene films efficiently postpone the hermeticity failure of the partially cracked coating. The authors assessed the coating performance against prolonged exposure to biomimetic physiological conditions using coated magnesium films, platinum interdigitated electrodes, and optoelectronic devices prepared on stretchable substrates. Designed extension of the lifetime preventing direct failures reduces from over 5 years yet tolerates the lifetime of 3 years even with the presence of critical damage, while others will directly fail less than two months at 37 °C. This strategy should accelerate progress on thin hermetic packaging for miniaturized and compliant implantable electronics.

The roles of atomic layer deposition (ALD) coatings on the stability of FeF3 Na-ion cathodes

Atomic layer deposition (ALD) has been used to stabilize Na-ion battery (SIB) electrodes but the role of ALD coatings and the mechanism of the improvements remain unclear, particularly in conversion-type cathodes. Here, we study for the first time the influence of alumina and titania (Al2O3 and TiO2) ALD coatings on conversion FeF3 cathodes in SIBs. Post-mortem analysis revealed that active material in both samples developed a small fraction of iron oxyfluoride (FeOF) during cycling. Similarly, the in-situ fluorination of both ALD oxide coatings led to the formation of aluminum and titanium oxyfluorides. The aluminum oxyfluoride formed a conformal passivating layer that was well adhered to the cathode electrolyte interphase (CEI). As a result, the Al2O3 coating reduced direct contact between the active material and the liquid electrolyte, minimized active material dissolution and significantly improved the overall electrochemical performance of FeF3 cathodes in SIBs. In contrast, the in-situ fluorination of the TiO2 ALD layer failed to produce a defect-free passivating layer and was inefficient in preventing side reactions, leading to the inferior performance.

Atomic Layer Nucleation Engineering: Inhibitor-Free Area-Selective Atomic Layer Deposition of Oxide and Nitride

Area-selective atomic layer deposition (AS-ALD) has attracted attention due to the process demand for semiconductor device scaling. Here, we propose the “atomic layer nucleation engineering (ALNE)” technique, an inhibitor-free AS-ALD of an oxide (Al2O3) and a nitride (AlN) with nearly 100% selectivity between the dielectric (SiO2) and the metal (Pt). The key is to add a radio-frequency substrate bias after precursor exposure and purge in each ALD cycle, where the energy from the ignited plasma selectively removes the precursors on the metal owing to the relatively lower binding energy compared to those on the dielectric, thereby inhibiting the film growth on the metal. This critical step enables the AS-ALD without selectivity loss up to 100 ALD cycles, leading to significant thickness differences of ∼14.9 and ∼8.7 nm for Al2O3 and AlN between the dielectric and metal surfaces. The realization of AS-ALD of Al2O3 and AlN by ALNE is also confirmed on the Pt/SiO2 patterned substrate. The ALNE offers a novel concept and approach to achieve high-selectivity AS-ALD, which is critical to further extension of Moore’s law.

Nano-Laminated Metal Oxides/Polyamide Stretchable Moisture- and Gas-Barrier Films by Integrated Atomic/Molecular Layer Deposition.

Stretchable barrier films capable of maintaining high levels of moisture- and gas-barrier performance under significant mechanical strains are a critical component for wearable/flexible electronics and other devices, but realization of stretchable moisture-barrier films has not been possible due to the inevitable issues of strain-induced rupturing compounded with moisture-induced swelling of a stretched barrier film. This study demonstrates nanolaminated polymer/metal oxide stretchable moisture-barrier films fabricated by a novel molecular layer deposition (MLD) process of polyamide-2,3 (PA-2,3) integrated with atomic layer deposition (ALD) metal oxide processes and an in situ surface-functionalization technique. The PA-2,3 surface upon in situ functionalization with H2O2 vapor offers adequate surface chemisorption sites for rapid nucleation of ALD oxides, minimizing defects at the PA-2,3/oxide interfaces in the nanolaminates. The integrated ALD/MLD process enables facile deposition and precise structural control of many-layered oxide/PA-2,3 nanolaminates, where the large number of PA-2,3 nanolayers provide high tolerance against mechanical stretching and flexing thanks to their defect-decoupling and stress-buffering functions, while the large number of oxide nanolayers shield against swelling by moisture. Specifically, a nanolaminate with 72 pairs of alternating 2 nm (5 cycles) PA-2,3 and 0.5 nm HfO2 (five cycles) maintains its water vapor transmission rate (WVTR) at the 10-6 g/m2 day level upon 10% tensile stretching and 2 mm-radius bending, a significant breakthrough for the wearable/flexible electronics technologies.

Fe Doping in LiMn1.5Ni0.5O4 by Atomic Layer Deposition Followed by Annealing: Depths and Occupation Sites

The development of high-voltage cathodes is very important to meet the pursuit of high energy and power density for next-generation lithium-ion batteries. LiMn1.5Ni0.5O4 (LMNO), as one of the most promising high-voltage cathodes, is still challenged by unstable surface chemistry, metal dissolution, and structure transition during charge/discharge cycling. In this work, a porous structure combined with Fe doping in LMNO was achieved by iron oxide (FeOx) atomic layer deposition (ALD) and postannealing. The formation of the porous structure was closely related to FeOx ALD, and the sites of Fe doping in LMNO spinel were also controlled by annealing temperature. After this modification, Li+ transport and cycling stability were both significantly improved.

Optimal design of novel precursor materials for the atomic layer deposition using computer-aided molecular design

Nanomaterials and nanostructures with multi-functional properties found widespread applications such as electronics, optics, and coatings that can be fabricated using Atomic Layer Deposition (ALD). ALD is a vapor phase deposition technique to generate thin films of metals and metal oxides on a substrate. In this process, a precursor, which often comprises of organic functional groups that surround the depositing metal, chemisorbs on the substrate or reacts with the surface sites and with each other. Precursor chemisorption on the substrate leads ALD to be a self-limiting process. Thus, the precursor(s) should be chosen in a way to enhance deposition based on the ALD conditions. For a given application, it is practically impossible to carry out a large number of experiments using numerous precursors with varied deposition conditions to find the one that maximizes the growth rate in ALD. In addition, only existing precursors can be tested experimentally. The overall objective of this work is to develop a computational tool for the in-silico design of precursor materials using adsorbate solid solution theory (ASST). In the first part of this paper, we apply the ASST to derive properties of the functional groups present in the precursor using a new Group Contribution Method (GCM). The GCM is successfully derived and compared with the experimental data from ALD. The method shows good agreement and is useful for the design of novel materials. In the second part of this paper, using the thermodynamic properties as obtained from GCM, we develop a computer-aided molecular design (CAMD) framework for the optimal design of novel precursor materials with enhanced deposition properties for the ALD of metal oxides and metals. The metaheuristic efficient ant colony optimization algorithm (EACO) developed in-house is used for both parts. CAMD is a combinatorial optimization methodology, where molecules with optimal desired properties are generated from functional groups. The precursor selection optimization problem is posed as a mixed integer nonlinear programming problem, which is solved using EACO. The ALD growth kinetics is used as an objective of optimization and a solution is validated with thermodynamic constraints. Along with the number of groups, the temperature is also included in the optimization framework as decision variables. Forty-one novel titanium precursor molecular structures for ALD are generated with growth rates ranging from 1.23 Å/cycle to as high as 1.65 Å/cycle. Thus, these precursors have shown growth rates higher than the known titanium precursors. ALD growth rate is found to be a function of the combination of the precursor functional groups as well as temperature with a complex correlation among them.