Oblique Angle Deposition of Germanium Film on Silicon Substrate

The effect of flux angle, substrate temperature and deposition rate on obliquely deposited germanium (Ge) films has been investigated. By carrying out deposition with the vapor flux inclined at 87° to the substrate normal at substrate temperatures of 250°C or 300°C, it may be possible to obtain isolated Ge nanowires. The Ge nanowires are crystalline as shown by Raman Spectroscopy.Singapore-MIT Alliance (SMA

Impact of the Glancing Angle Deposition on the Yttria-Stabilized Zirconia Growth and Their Thermal Barrier Coating Properties

Yttria-stabilized zirconia (YSZ) is the most common material used as a thermal barrier in several engineering applications. The majority of films produced by physical vapor deposition (PVD) techniques use normal incidence and lead to the columnar growth normal to the substrate. The typical columnar structure of sputter-deposited films is largely influenced, among other parameters, by pressure, temperature, thickness, and the ion-to-atom ratio incident at the substrate or substrate bias voltage. Another important experimental parameter used to modify the film properties is the direction of the incident flux of the depositing species with respect to the substrate surface. In this chapter an oblique angle deposition (OAD) approach was used to grow YSZ with tilted columnar structures, to study the impact of this deposition technique on the microstructure, morphology, and, correspondingly, the thermal conductivity of YSZ films, in order to improve the insulator potential of these thin films. Additionally, in the chapter, we present a detailed description of the oblique angle deposition (OAD) technique and double-layer model used for determination of the effective thermal conductivity of YSZ samples grown over thick substrates

Blending of nanoscale and microscale in uniform large-area sculptured thin-film architectures

The combination of large thickness ($>3$ $\mu$m), large--area uniformity (75 mm diameter), high growth rate (up to 0.4 $\mu$m/min) in assemblies of complex--shaped nanowires on lithographically defined patterns has been achieved for the first time. The nanoscale and the microscale have thus been blended together in sculptured thin films with transverse architectures. SiO$_x$ ($x\approx 2$) nanowires were grown by electron--beam evaporation onto silicon substrates both with and without photoresist lines (1--D arrays) and checkerboard (2--D arrays) patterns. Atomic self--shadowing due to oblique--angle deposition enables the nanowires to grow continuously, to change direction abruptly, and to maintain constant cross--sectional diameter. The selective growth of nanowire assemblies on the top surfaces of both 1--D and 2--D arrays can be understood and predicted using simple geometrical shadowing equations.Comment: 17 pages, 9 figure

Optical Characterization of Silver Nanorod Thin Films Grown Using Oblique Angle Deposition

Nanorods are metamaterial structures that have been shown to have wide application, ranging from biomedical uses to photovoltaic materials. These materials have unique optical characteristics. In this paper, two silver (Ag) nanorod thin-film samples are created using Glancing Angle Deposition (GLAD) at both near-room temperature (~300 K) and cryogenic temperature (~100 K). Generalized ellipsometry is used to measure the optical constants of the samples. The strong difference between the optical constants of the constituent materials and those of these thin films shows that the characteristics of the samples are due to how their metamaterial structures are defined. The principle optical axes of the films align well with the morphological characteristics of the nanostructures. The axis with the greatest index of refraction remains aligned to the principle axes but shifts orientation with respect to morphological characteristics between samples. Experimental results show differences in both magnitude and characteristics of the nanorod indexes. Reflectance and transmittance measurements are performed to extract absorptance data. The room temperature deposited sample shows a higher overall absorptance, while the cryogenic sample shows a clear orientation-dependent absorptance. Polarization data is analyzed to show that the 100 K thin film exhibits polarization-dependent absorptance, while the 300 K sample’s absorptance has a strong orientation dependence

Optical Characterization of Silver Nanorod Thin Films Grown Using Oblique Angle Deposition

Nanorods are metamaterial structures that have been shown to have wide application, ranging from biomedical uses to photovoltaic materials. These materials have unique optical characteristics. In this paper, two silver (Ag) nanorod thin-film samples are created using Glancing Angle Deposition (GLAD) at both near-room temperature (~300 K) and cryogenic temperature (~100 K). Generalized ellipsometry is used to measure the optical constants of the samples. The strong difference between the optical constants of the constituent materials and those of these thin films shows that the characteristics of the samples are due to how their metamaterial structures are defined. The principle optical axes of the films align well with the morphological characteristics of the nanostructures. The axis with the greatest index of refraction remains aligned to the principle axes but shifts orientation with respect to morphological characteristics between samples. Experimental results show differences in both magnitude and characteristics of the nanorod indexes. Reflectance and transmittance measurements are performed to extract absorptance data. The room temperature deposited sample shows a higher overall absorptance, while the cryogenic sample shows a clear orientation-dependent absorptance. Polarization data is analyzed to show that the 100 K thin film exhibits polarization-dependent absorptance, while the 300 K sample’s absorptance has a strong orientation dependence

Networking Behavior in Thin Film and Nanostructure Growth Dynamics

Thin film coatings have been essential in development of several micro and nano-scale devices. To realize thin film coatings various deposition techniques are employed, each yielding surface morphologies with different characteristics of interest. Therefore, understanding and control of the surface growth is of great interest. In this paper, we devise a novel network-based modeling of the growth dynamics of such thin films and nano-structures. We specifically map dynamic steps taking place during the growth to components (e.g., nodes, links) of a corresponding network. We present initial results showing that this network-based modeling approach to the growth dynamics can simplify our understanding of the fundamental physical dynamics such as shadowing and re-emission effects