Showing papers on "Ellipsometry published in 2023"

Mapping spectroscopic micro-ellipsometry with sub-5 microns lateral resolution and simultaneous broadband acquisition at multiple angles.

Abstract: Spectroscopic ellipsometry is a widely used optical technique in both industry and research for determining the optical properties and thickness of thin films. The effective use of spectroscopic ellipsometry on micro-structures is inhibited by technical limitations on the lateral resolution and data acquisition rate. Here, we introduce a spectroscopic micro-ellipsometer (SME), capable of recording spectrally resolved ellipsometric data simultaneously at multiple angles of incidence in a single measurement of a few seconds, with a lateral resolution down to 2 μm in the visible spectral range. The SME can be easily integrated into generic optical microscopes by the addition of a few standard optical components. We demonstrate complex refractive index and thickness measurements by using the SME, which are in excellent agreement with a commercial spectroscopic ellipsometer. The high lateral resolution is displayed by complex refractive index and thickness maps over micron-scale areas. As an application for its accuracy and high lateral resolution, the SME can characterize the optical properties and number of layers of exfoliated transition-metal dichalcogenides and graphene, for structures that are a few microns in size.

Exhibition of a film's resonances in ellipsometric spectra and the Berreman effect.

Abstract: Ellipsometry is a powerful and sensitive optical method for the investigation of surfaces and thin films. However, the absence of possibilities for direct interpretation of the ellipsometric spectra creates an impression of the complexity of this method and the difficulty in its application, so any approach for qualitative interpretation of the ellipsometric spectra is very desirable. This work is devoted to this problem with the example of the modulation of the ellipsometric spectra of a substrate by the resonances of a thin deposited film.

Linear and nonlinear optical properties of Al2O3/Y2O3 nanolaminates fabricated by atomic layer deposition

Abstract: The structure and composition of nanocomposites constitute design parameters that can be manipulated to get control over their linear and nonlinear optical response. In this work, we report the linear and nonlinear optical properties of samples consisting of multiple Al2O3/Y2O3 bilayers with a total thickness of ∼ 500 nm, fabricated through the atomic layer deposition technique onto Si and SiO2 substrates. Fabrication of the multiple layer configurations was made for four Y2O3 layer thicknesses, while maintaining a constant Al2O3 layer thickness for all the samples fabricated. Physical and chemical characterization of the samples produced was conducted by optical ellipsometry, transmission electron microscopy and XRD. Moreover, their third-order nonlinear optical properties were studied through the z-scan technique with 100 fs pulses at 800 nm from a Ti:Sapphire laser, allowing the resolution of the refractive and absorptive contributions to the response. The nonlinear parameters extracted from the experiments are discussed in terms of the fabrication thickness of the selected materials. Additionally, figures of merit relevant for the possible application of these materials in optical processing system are calculated and discussed.

Real-Time Ellipsometry at High and Low Temperatures

Abstract: Among the many available real-time characterization methods, ellipsometry stands out with the combination of high sensitivity and high speed as well as nondestructive, spectroscopic, and complex modeling capabilities. The thicknesses of thin films such as the complex dielectric function can be determined simultaneously with precisions down to sub-nanometer and 10–4, respectively. Consequently, the first applications of high- and low-temperature real-time ellipsometry have been related to the monitoring of layer growth and the determination of optical properties of metals, semiconductors, and superconductors, dating back to the late 1960s. Ellipsometry has been ever since a steady alternative of nonpolarimetric spectroscopies in applications where quantitative information (e.g., thickness, crystallinity, porosity, band gap, absorption) is to be determined in complex layered structures. In this article the main applications and fields of research are reviewed.

Optimization of optical and structural properties of Al2O3/TiO2 nano-laminates deposited by atomic layer deposition for optical coating.

Abstract: Optimizing the atomic layer deposition (ALD) process of films is particularly important in preparing multilayer interference films. In this work, a series of Al2O3/TiO2 nano-laminates with a fixed growth cycle ratio of 1:10 were deposited on Si and fused quartz substrates at 300 °C by ALD. The optical properties, crystallization behavior, surface appearance and microstructures of those laminated layers were systematically investigated by spectroscopic ellipsometry, spectrophotometry, X-ray diffraction, atomic force microscope and transmission electron microscopy. By inserting Al2O3 interlayers into TiO2 layers, the crystallization of the TiO2 is reduced and the surface roughness becomes smaller. The TEM images show that excessively dense distribution of Al2O3 intercalation leads to the appearance of TiO2 nodules, which in turn leads to increased roughness. The Al2O3/TiO2 nano-laminate with a cycle ratio 40:400 has relatively small surface roughness. Additionally, oxygen-deficient defects exist at the interface of Al2O3 and TiO2, leading to evident absorption. Using O3 as an oxidant instead of H2O for depositing Al2O3 interlayers was verified to be effective in reducing absorption during broadband antireflective coating experiments.

Implications of Electron Transport Layer and Back Metal Contact Variations in Tin-Lead Perovskite Solar Cells Assessed by Spectroscopic Ellipsometry and External Quantum Efficiency.

Abstract: The structural and optical properties of hybrid organic-inorganic metal halide perovskite solar cells are measured by spectroscopic ellipsometry to reveal an optically distinct interfacial layer among the back contact metal, charge transport, and absorber layers. Understanding how this interfacial layer impacts performance is essential for developing higher performing solar cells. This interfacial layer is modeled by Bruggeman effective medium approximations (EMAs) to contain perovskite, C60, BCP, and metal. External quantum efficiency (EQE) simulations that consider scattering, electronic losses, and the formation of nonparallel interfaces are created with input derived from ellipsometry structural-optical models and compared with experimental EQE to estimate optical losses. This nonplanar interface causes optical losses in short circuit current density (JSC) of up to 1.2 mA cm-2. A study of glass/C60/SnO2/Ag or Cu and glass/C60/BCP/Ag film stacks shows that C60 and BCP mix, but replacing BCP with SnO2 can prevent mixing between the ETLs to prevent contact between C60 and back contact metal and enable the formation of a planar interface between ETLs and back contact metals.

In-Operando Optical Spectroscopy of Field-Effect-Gated Al-Doped ZnO.

Abstract: Transparent conductive oxides (TCO) have the unique characteristics of combining optical transparency with high electrical conductivity; such a property makes them uniquely alluring for applications in visible and infrared photonics. One of their most interesting features is the large sensitivity of their optical response to the doping level. We performed the active electrical manipulation of the dielectric properties of aluminum-doped ZnO (AZO), a TCO-based on Earth-abundant elements. We actively tuned the optical and electric performances of AZO films by means of an applied voltage in a parallel-plate capacitor configuration, with SrTiO3 as the dielectric, and monitored the effect of charge injection/depletion by means of in-operando spectroscopic ellipsometry. Calculations of the optical response of the gated system allowed us to extract the spatially resolved variations in the dielectric function of the TCO and infer the injected/depleted charge profile at the interface.

Reversible Tuning of Extrinsic 3D Chirality in Chalcogenide NonChiral Metasurfaces

Abstract: The chiroptical response occurring in the chiral metamaterials (MMs) has crucial and extensive applications for stereochemistry, polarization optics, and spintronics. Yet, such intrinsically chiral metamaterials are restricted to a complicated subwavelength chiral profile, causing pronounced fabrication challenges, particularly at the near‐infrared (N‐IR) spectral regime. Instead, extrinsic chirality can also be observed in the nonchiral MMs under an oblique incidence, indicating that the chiroptical response can be achieved with simple structures. The development of photon‐spin selective integrated devices needs an actively reversible tuning of chirality in MMs. Herein, a reversible switching of the extrinsic chirality at the N‐IR region is demonstrated by integrating a nonvolatile chalcogenide semiconductor, Ge2Sb2Te5, into the nonchiral MMs design. It provides an ultrafast and reconfigurable tuning of transmittance circular dichroism (TCD) between amorphous and crystalline states under a stimulus of a nanosecond pulsed laser at a wavelength of 532 nm. Meanwhile, it also effectively manipulates the TCD by titling both rotation and incident angles while fixing geometrical parameters. Utilizing ellipsometry and analytical inversion, it can obtain not only linear but circular birefringence‐dichroism pairs from a single general ellipsometry measurement, which gives a comprehensive description of the polarization characteristics of the non‐chiral MMs, having an advantage over the typical circular dichroism measurements.

Thermal oxidation of lattice mismatched Al1-xInxN films on GaN

Abstract: Lattice-mismatched Al1-xInxN layers grown on GaN and with varying x are thermally oxidized to understand how alloy content affects the oxidation process and oxide films. The samples are oxidized in a horizontal tube furnace at 830 oC and 900 oC for 2 h under O2. The samples are characterized using atomic force microscopy to determine root mean square roughness before and after oxidation. The oxide thickness for each sample is determined by spectroscopic ellipsometry. The AlInN layers with less indium produce smoother oxide layers, and the oxidation rate of the samples increases with increasing indium content. Energy dispersive X-ray spectroscopy of scanning transmission electron microscopy images of the oxide layers show the In collects on or near the surface of the oxide layer. Overall, the results indicate that oxides formed from AlInN layers with less indium produce smoother oxide films and are more suitable for device applications.

1,4-Bis(trimethylsilyl)piperazine—Thermal Properties and Application as CVD Precursor

Abstract: We report an investigation into 1,4-Bis-N,N-(trimethylsilyl)piperazine (BTMSP) as a novel precursor for the synthesis of silicon carbonitride films by chemical vapor deposition (CVD). The thermal stability, temperature dependence of vapor pressure and thermodynamic constants of the evaporation process of BTMSP were determined by static tensimetry with a glass membrane zero manometer. The transformation of the compound in low-power (25 W) plasma conditions was investigated by optical emission spectroscopy. It was shown that BTMSP undergoes destruction, accompanied by H and CH elimination and CN formation. SiCN(H) films were deposited in a hot-wall plasma-enhanced CVD reactor. The optical properties of the films were studied by spectral ellipsometry (refractive index: 1.5–2.2; absorption coefficient: 0–0.12) and UV–Vis spectroscopy (transmittance: up to 95%; optical bandgap: 1.6–4.9 eV). Information on the aging behavior of the films is also provided. The transformation of the films occurred through water adsorption and the formation of Si–O bonds with the degradation of Si–H, N–H and Si–CHx–Si bonds.

Nanostructures for in-situ surface-enhanced Kretschmann-Raether ellipsometry

Abstract: Spectroscopic ellipsometry is a sensitive and optical model-supported quantitative tool to monitor interfaces. In this work, solid-liquid interfaces are studied using the Kretschmann-Raether configuration for biosensing applications. The interface layers support two purposes simultaneously: (i) chemical suitability for the adsorption of molecules to be detected and (ii) the optical enhancement of the signal to increase the sensitivity. Ellipsometry is not only used as a sensor but also as a quantitative measurement tool to study and understand the interface phenomena, and to develop the sensing layers for the largest possible optical sensitivity. Plasmonic and structured layers are of primary importance in terms of optical sensitivity. Layers structured both in lateral and vertical directions have been studied. Optical models based on both the transfer matrix and the finite element method were developed and used for the structural analysis where the material and geometrical derivatives are used in the inverse fitting process of the model data to the measurement. Structures utilizing plasmonic, diffraction, multilayer field enhancement, and other methods were analyzed as possible candidates for the improvement of the optical performance of the cell. Combinatorial and periodic plasmonic surface structures were developed to enhance the sensitivity of in-situ ellipsometry at solid-liquid interfaces utilizing the Kretschmann-Raether (KR) geometry. AgxAl1−x layers with variable compositions and Au layers with changing periods and critical dimensions were investigated to improve the performance of sensors based on the KR arrangement.

Atomic layer deposited gallium oxide thin film monitored by continuous in-situ spectroscopic ellipsometry (Conference Presentation)

Abstract: The growth of a-GaOx thin films by plasma-enhanced atomic layer deposition is studied by in-situ spectroscopic ellipsometry. A method is developed to extract the dielectric constant and thickness of ultrathin films (< 1 nm) unambiguously. The optical properties were calculated after each step and for all cycles, which allows to follow their evolution until a “bulk-like” gallium oxide film is reached. We show that a-GaOx films can be self-doped with the introduction of oxygen vacancies to obtain semiconducting properties. With additional information retrieved from the in-situ monitoring, a better understanding and faster development of growth processes are gained.

Diffractive Refractometer Based on Scalar Theory

Abstract: The measurement of the refractive index typically requires the use of optical ellipsometry which, although potentially very accurate, is extremely sensitive to the structural properties of the sample and its theoretical modeling, and typically requires specialized expertise to obtain reliable output data. Here, we propose a simple diffractive method for the measurement of the refractive index of homogenous solid thin films, which requires only the structuring of the surface of the material to be measured with the profile of a diffraction grating. The refractive index of an exemplary soft-moldable material is successfully estimated over a wide wavelength range by simply incorporating the measured topography and diffraction efficiency of the grating into a convenient scalar theory-based diffraction model. Without the need for specialized expertise and equipment, the method can serve as a simple and widely accessible optical characterization of materials useful in material science and photonics applications.

Characterization of Nitrogen-Doped TiO2 Films Prepared by Arc Ion Plating without Substrate Heating in Various N2/O2 Gas Mixture Ratios

Abstract: Nitrogen-doped TiO2 films exhibit good photocatalytic ability in the visible (VIS) light region. This study reports the fabrication of these films using arc ion plating (AIP) in different ratios of nitrogen partial pressure (PN2) to oxygen partial pressure (PO2) without substrate heating and/or applied bias. This approach allows a significant broadening of the range of possible substrates to be used. X-ray diffraction (XRD) patterns indicate that these films deposited at room temperature are amorphous, and surface electron microscope (SEM) and atomic force microscope (AFM) images show that they have rough surfaces. Their transmittance and optical properties are measured with a spectrometer and ellipsometer, respectively. In addition, the bandgap energies of these amorphous films are derived by the ellipsometer from the Tauc–Lorentz (TL) model. The results indicate that the N-doped TiO2 film with a PN2/PO2 ratio of 1/4 attains the narrowest bandgap and the highest absorbance in the visible region. It can be attributed to the prominent Ti–N peaks observed in the sample’s Ti and N X-ray photoelectron spectroscopy (XPS) spectra. In addition, verified with the methylene blue (MB) test, this sample exhibits the best photocatalytic performance for its narrowest energy gap.

Comparative Electrokinetic Study of Alginate-Coated Colloidal Particles

Abstract: Alginates are a family of natural polysaccharides with promising potential in biomedical applications and tissue regeneration. The design of versatile alginate-based structures or hydrogels and their stability and functionality depend on the polymer’s physicochemical characteristics. The main features of alginate chains that determine their bioactive properties are the molar ratio of mannuronic and glucuronic residues (M/G ratio) and their distribution along the polymer chain (MM-, GG-, and MG blocks). The present study is focused on investigating the influence of the physicochemical characteristics of alginate (sodium salt) on the electrical properties and stability of the dispersion of polymer-coated colloidal particles. Ultrapure and well-characterized biomedical-grade alginate samples were used in the investigation. The dynamics of counterion charge near the vicinity of adsorbed polyion is studied via electrokinetic spectroscopy. The results show that the experimental values of the frequency of relaxation of the electro-optical effect are higher compared to the theoretical ones. Therefore, it was supposed that polarization of the condensed Na+ counterions occurs at specific distances according to the molecular structure (G-, M-, or MG-blocks). In the presence of Ca2+, the electro-optical behavior of the particles with adsorbed alginate molecules almost does not depend on the polymer characteristics but was affected by the presence of divalent ions in the polymer layer.

Polarized angle-resolved spectral reflectometry for real-time ultra-thin film measurement.

Abstract: We propose a polarized, angle-resolved spectral (PARS) reflectometry for simultaneous thickness and refractive-index measurement of ultra-thin films in real time. This technology acquires a two-dimensional, angle-resolved spectrum through a dual-angle analyzer in a single shot by radially filtering the back-focal-plane image of a high-NA objective for dispersion analysis. Thus, film parameters, including thickness and refractive indices, are precisely fitted from the hyper-spectrum in angular and wavelength domains. Through a high-accuracy spectral calibration, a primary PARS system was built. Its accuracy was carefully verified by testing a set of SiO2 thin films of thicknesses within two µm grown on monocrystalline-Si substrates against a commercial spectroscopic ellipsometer. Results show that the single-shot PARS reflectometry results in a root-mean-square absolute accuracy error of ∼1 nm in film thickness measurement without knowing its refractive indices.

Temperature-Dependent Anisotropic Refractive Index in β-Ga2O3: Application in Interferometric Thermometers

Abstract: An accurate knowledge of the optical properties of β-Ga2O3 is key to developing the full potential of this oxide for photonics applications. In particular, the dependence of these properties on temperature is still being studied. Optical micro- and nanocavities are promising for a wide range of applications. They can be created within microwires and nanowires via distributed Bragg reflectors (DBR), i.e., periodic patterns of the refractive index in dielectric materials, acting as tunable mirrors. In this work, the effect of temperature on the anisotropic refractive index of β-Ga2O3 n(λ,T) was analyzed with ellipsometry in a bulk crystal, and temperature-dependent dispersion relations were obtained, with them being fitted to Sellmeier formalism in the visible range. Micro-photoluminescence (μ-PL) spectroscopy of microcavities that developed within Cr-doped β-Ga2O3 nanowires shows the characteristic thermal shift of red–infrared Fabry–Perot optical resonances when excited with different laser powers. The origin of this shift is mainly related to the variation in the temperature of the refractive index. A comparison of these two experimental results was performed by finite-difference time-domain (FDTD) simulations, considering the exact morphology of the wires and the temperature-dependent, anisotropic refractive index. The shifts caused by temperature variations observed by μ-PL are similar, though slightly larger than those obtained with FDTD when implementing the n(λ,T) obtained with ellipsometry. The thermo-optic coefficient was calculated.

Mid-infrared optical properties of non-magnetic-metal/CoFeB/MgO heterostructures

Abstract: We report on the optical characterization of non-magnetic metal (NM)/ferromagnetic (Co20Fe60B20)/MgO heterostructures and interfaces by using mid infrared (MIR) spectroscopic ellipsometry at room temperature. We extracted for the MIR range the dielectric function (DF) of Co20Fe60B20, that is lacking in literature, from a multisample analysis. From the optical modeling of the heterostructures we detected and determined the dielectric tensor properties of a two-dimensional electron gas (2DEG) forming at the NM and the CoFeB interface. These properties comprise independent Drude parameters for the in-plane and out-of plane tensor components, with the latter having an epsilon-near-zero frequency within our working spectral range. A feature assigned to spin–orbit coupling (SOC) is identified. Furthermore, it is found that both, the interfacial properties, 2DEG Drude parameters and SOC strength, and the apparent DF of the MgO layer depend on the type of the underlying NM, namely, Pt, W, or Cu. The results reported here should be useful in tailoring novel phenomena in such types of heterostructures by assessing their optical response noninvasively, complementing existing characterization tools such as angle-resolved photoemission spectroscopy, and those related to electron/spin transport.

Influence of Effective Mass on Carrier Concentration for PEDOT:PSS and S-PEDOT Thin Films Studied by Ellipsometry and Hall Measurement

Abstract: We herein investigate the optical anisotropy, carrier concentration, and carrier mobility in the transparent conductive polymer poly(3,4-ethylendioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) and self-doped PEDOT (S-PEDOT) using spectroscopic ellipsometry and Hall measurements in the van der Pauw configuration. The influence of the effective mass on the electrical carrier concentrations and mobility is demonstrated in PEDOT:PSS and S-PEDOT thin films with different carrier concentrations. The optical carrier concentration determined by ellipsometry and Hall measurements in both PEDOT:PSS and S-PEDOT shows good agreement in a collinear relationship by considering the variation of effective mass. Conversely, the electron mobility values obtained from spectroscopic ellipsometry and Hall measurements exhibit rather poor agreement. These findings are thought to originate from the grain boundaries at between PEDOT nanocrystals.

Behaviour of Monolayers Tetraether Lipids Caldarchaeol-PO4 on the Modification of the Solid Surface-supported Wafer Silicon to Amino-silanised: Comparison of Analysis Studies between Langmuir-Blodgett Monolayers with Self-Assembled Monolayers

Abstract: This study analyzed the behaviour of organization molecular chemically modified tetraether lipids caldarchaeol-PO4 on the modification of the solid surface-supported wafer silicon to amino-silanised using Langmuir-Blodgett films, Self Assembling Monolayers (SAMs), ellipsometry, and atomic force microscopy (AFM). On the silicon wafer with an amino-silaned surface, the monolayers of caldarchaeol-PO4 remained stable. By using the Langmuir-Blodgett technique and SAMs, the organisations of molecular monolayers of caldarchaeol-PO4 have been examined. In the Langmuir-Blodgett procedure, surface pressure is carried out in monolayers of more flat, inhomogeneous caldarchaeol-PO4. A large flat domain is displayed by another way of monolayers caldarchaeol-PO4 using SAMs. Monolayers caldarchaeol-PO4 by the Langmuir-Blodgett method appears to be stable and chemically resistant after washing with organic solvent and an additional treatment ultrasonification with various lipid thicknesses of about 2 nm to 6 nm. Conversely monolayers caldarchaeol-PO4 by SAMs appear less than monolayers caldarchaeol-PO4 by the Langmuir-Blodgett method, thicknesses varying from 1 nm to 3 nm.

Growth kinetics of the adsorbed layer of poly(bisphenol A carbonate) and its effect on the glass transition behavior in thin films

Abstract: The glass transition behavior of thin films of poly(bisphenol A carbonate) (PBAC) was studied employing ellipsometry. The glass transition temperature increases with the reduction of the film thickness. This result is attributed to the formation of an adsorbed layer with a reduced mobility compared to bulk PBAC. Therefore, for the first time, the growth kinetics of the adsorbed layer of PBAC was investigated, prepared by leaching samples from a 200 nm thin film which were annealed for several times at three different temperatures. The thickness of each prepared adsorbed layer was measured by multiple scans using atomic force microscopy (AFM). Additionally, an unannealed sample was measured. Comparison of the measurements of the unannealed and the annealed samples provides proof of a pre-growth regime for all annealing temperatures which was not observed for other polymers. For the lowest annealing temperature after the pre-growth stage only a growth regime with a linear time dependence is observed. For higher annealing temperatures the growth kinetics changes from a linear to a logarithmic growth regime at a critical time. At the longest annealing times the films showed signs of dewetting where segments of the adsorbed film were removed from the substrate (dewetting by desorption). The dependence of the surface roughness of the PBAC surface on annealing time also confirmed that the films annealed at highest temperatures for the longest times desorbed from the substrate.

Probing the tightly bound layer in poly(vinyl alcohol) thin films using swelling measurements.

Abstract: A strongly adsorbed, tightly bound polymer layer can exist at the polymer/substrate interface in polymer thin films and polymer nanocomposites. The characteristics of the tightly bound layer have long been of interest because of its effect on physical properties. However, direct investigations are challenging as the layer is buried deep within the sample. A common approach to access the tightly bound layer is by rinsing or washing away the loosely bound polymer using a good solvent. While this enables direct investigations of the tightly bound layer, it is unclear if the layer remains unperturbed by the preparation process. Therefore, in situ techniques that can probe the tightly bound layer without strongly perturbing it are preferable. In previous work (P. D. Lairenjam, S. K. Sukumaran and D. K. Satapathy, Macromolecules, 2021, 54, 10931-10942), we introduced an approach to estimate the thickness of the tightly bound layer at the chitosan/silicon interface using swelling of nanoscale thin films when exposed to solvent vapour. To determine the general validity of the approach, in this work we investigated the swelling of poly(vinyl alcohol) (PVA) thin films using two independent techniques: spectroscopic ellipsometry and X-ray reflectivity. We found that the swelling kinetics for thin films of initial thickness in the range 18-215 nm could be described by a single time-dependent swelling ratio, c(t), provided we account for a tightly bound layer of thickness 15 nm at the polymer/substrate interface. Consistent with the conclusions from the swelling measurements, electron density profiles determined by modeling X-ray reflectivity data clearly indicated the existence at the polymer/substrate interface of a 15 nm thick layer of a slightly higher density than the rest of the film. The early-time diffusion coefficient of H2O in PVA determined from the temporal evolution of the mass uptake of the solvent vapour was found to decrease by 3-4 orders of magnitude when the film thickness decreased by approximately an order of magnitude.

Heterostructure Films of SiO2 and HfO2 for High-Power Laser Optics Prepared by Plasma-Enhanced Atomic Layer Deposition

Abstract: Absorption losses and laser-induced damage threshold (LIDT) are considered to be the major constraints for development of optical coatings for high-power laser optics. Such coatings require paramount properties, such as low losses due to optical absorption, high mechanical stability, and enhanced damage resistance, to withstand high-intensity laser pulses. In this work, heterostructures were developed by sub-nanometer thin films of SiO2 and HfO2 using the plasma-enhanced atomic layer deposition (PEALD) technique. Thin-film characterization techniques, such as spectroscopic ellipsometry, spectrophotometry, substrate curvature measurements, X-ray reflectivity, and Fourier transform infrared spectroscopy, were employed for extracting optical constants, residual stress, layer formation, and functional groups present in the heterostructures, respectively. These heterostructures demonstrate tunable refractive index, bandgap, and improved optical losses and LIDT properties. The films were incorporated into antireflection coatings (multilayer stacks and graded-index coatings) and the LIDT was determined at 355 nm wavelength by the R-on-1 method. Optical absorptions at the reported wavelengths were characterized using photothermal common-path interferometry and laser-induced deflection techniques.