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Sculptured thin films and glancing angle deposition: Growth mechanics and applications
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1997
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Evaporation TechniqueOptical MaterialsEngineeringNanostructured SurfaceSurface NanotechnologyThin Film Process TechnologyChemical DepositionSurface TechnologyMaterials FabricationGrowth MechanicsThin Film ProcessingMaterials ScienceNanotechnologyNanomanufacturingAngle DepositionSurface NanoengineeringMicrofabricationMaterials CharacterizationApplied PhysicsSurface ScienceSculptured Thin FilmsNanofabricationThin FilmsSurface ProcessingChemical Vapor DepositionDimensional Microstructure
The study investigates the growth mechanics of sculptured thin films using density, SEM, and refractive index measurements. Sculptured thin films were fabricated by glancing angle deposition with computer‑controlled substrate motion, employing adatom diffusion and atomic shadowing to sculpt columnar microstructures and enabling dense capping layers via controlled rotation. The capping process success depends on technique, with an exponential decrease in incident flux angle over time reducing pore filling and fracturing, and GLAD shows promise for optical, biological, and chemical devices.
Sculptured thin films with three dimensional microstructure controlled on the 10 nm scale were fabricated with an evaporation technique. Glancing angle deposition (GLAD) and substrate motion were employed to “sculpt” columnar thin film microstructure into desired forms ranging from zigzag shaped to helical to four-sided “square” helical. Computer control of substrate motion was used to accurately position the substrate and to achieve the desired film structures. The growth mechanics of this novel thin film deposition technique are investigated with density measurements, scanning electron microscopy analysis, and measurements of effective refractive index. Adatom diffusion and atomic shadowing are the dominant growth mechanisms with glancing angle deposition conditions creating extreme shadowing. With controlled rotation of the substrate about two axes during deposition, a dense capping layer can be produced on top of the porous sculptured films. The success of the capping process was found to be strongly dependent on the technique used, with an exponential decrease (θ∝[1−A⋅eB⋅t]) with time of incident flux angle found to be the best to reduce filling of the porous film and fracturing of the capping film. The GLAD technique was found to have potentially promising application in optical, biological, and chemical devices and materials.