Glancing Angle Deposition Of Thin Films

This book provides a highly practical treatment of Glancing Angle Deposition (GLAD), a thin film fabrication technology optimized to produce precise nanostructures from a wide range of materials. GLAD provides an elegant method for fabricating arrays of nanoscale helices, chevrons, columns, and other porous thin film architectures using physical vapour deposition processes such as sputtering or evaporation. The book gathers existing procedures, methodologies, and experimental designs into a single, cohesive volume which will be useful both as a ready reference for those in the field and as a definitive guide for those entering it. It covers: Development and description of GLAD techniques for nanostructuring thin films Properties and characterization of nanohelices, nanoposts, and other porous films Design and engineering of optical GLAD films including fabrication and testing, and chiral films Post-deposition processing and integration to optimize film behaviour and structure Deposition systems and requirements for GLAD fabrication A patent survey, extensive relevant literature, and a survey of GLAD's wide range of material properties and diverse applications.

This book provides a highly practical treatment of Glancing Angle Deposition (GLAD), a thin film fabrication technology optimized to produce precise nanostructures from a wide range of materials. GLAD provides an elegant method for fabricating arrays of nanoscale helices, chevrons, columns, and other porous thin film architectures using physical vapour deposition processes such as sputtering or evaporation. The book gathers existing procedures, methodologies, and experimental designs into a single, cohesive volume which will be useful both as a ready reference for those in the field and as a definitive guide for those entering it. It covers: Development and description of GLAD techniques for nanostructuring thin films Properties and characterization of nanohelices, nanoposts, and other porous films Design and engineering of optical GLAD films including fabrication and testing, and chiral films Post-deposition processing and integration to optimize film behaviour and structure Deposition systems and requirements for GLAD fabrication A patent survey, extensive relevant literature, and a survey of GLAD's wide range of material properties and diverse applications.

Structuring of material on the nanoscale is enabling new functional materials and improving existing technologies. Glancing angle deposition (GLAD) is a physical vapor deposition technique that enables thin film fabrication with engineered columnar structures on the (10 to 100) nm scales. In this thesis, we have developed new methods for controlling the morphology, microstructure, and texture of as-deposited GLAD films and composite films formed by phase transformation of GLAD nanocolumn arrays during post-deposition annealing. These techniques are demonstrated by engineering the vapour flux motion in both Fe and ZnO nanorod deposition and FeS2 sulfur-annealing. Crystalline Fe nanorods with a tetrahedral apex can be grown under rapid continuous azimuthal rotation of the substrate during growth. Discontinuous azimuthal rotation with 3-fold symmetry that matches the nanocolumn's tetrahedral apex symmetry produces nanocolumns with in-plane morphological and crystal orientation. This method, called flux engineering, provides a general approach to induce biaxial crystal texture in faceted GLAD films. Similar effects were found for ZnO nanocolumns. Reliable production of photovoltaic-grade iron pyrite thin films has been challenging. Sulfur-annealing of bulk films often produces cracking or buckling. We used the flux-engineering processes developed for Fe to control the inter-column spacing of the precursor film. By precisely tuning the inter-column spacing of the precursor film we can produce iron pyrite films with increased crystallite sizes >100 nm with a uniform, crack-free, and facetted granular microstructure. Large crystallites may reduce carrier recombination at grain boundaries, which is attractive for photovoltaic cells. We assessed the viability of these films for photovoltaic applications with composition, electrical, and optical characterization. Notably, we found a 27 ps lifetime of photocarriers measured with ultrafast optical-pump/THz-probe and tested charge-separation characterization between the pyrite films and a conjugated polymer with absolute photoluminescence quenching measurements. These results provide the foundation for future improvements in pyrite processing for photovoltaic cells.

Thin-films grown via glancing-angle deposition (GLAD) have interesting structural, mechanical, and optical properties and may be used for a variety of applications including sensors, optical filters, antireflection coatings, fuel cells, and magnetic data storage. However, due in part to the complexity of the resulting thin-film structures as well as to the large range of time- and length- scales, realistic simulations of the thin-film growth process for large deposition angles have in the past been difficult. As a result, typically only simulations of effective models of GLAD, or of more realistic models for smaller deposition angles, have been carried out. As a first step in understanding the dependence of the surface morphology and microstructure in GLAD on deposition parameters, here we present the results of large-scale MD simulations of Cu/Cu(100) growth for the case of large deposition angle. In particular, by taking advantage of the speed of recently developed graphical-processing-units (GPUs) we have carried out large-scale GPU-enhanced MD simulations of Cu/Cu(100) growth up to 20 monolayers (ML) for deposition angles (corresponding to the angle with respect to the substrate normal) ranging from 50o to 85o and for both random and fixed azimuthal angles. In general, we find good agreement with experiment results for the dependence of thin-film porosity on deposition angle and film-thickness. Results for the dependence of the surface roughness, lateral correlation length and microstructure (e.g. defect density, vacancy density, surface sites, and strain) on the deposition angle and film thickness are also presented.