11/9/2023 0 Comments Lattice semiconductor bethlehem pa![]() Lattice rotation in this new mode of crystal growth occurs upon crystallization through a well-organized dislocation/disclination structure introduced at the glass/crystal interface. The proof-of-concept including key characteristics of RLS crystals is demonstrated using the example of Sb 2S 3 crystals within the Sb-S-I model glass system for which the rotation rate depends on the direction of laser scanning relative to the orientation of initially formed seed. Here we report a novel approach to fabricate RLS crystal lines and 2D layers of unlimited dimensions via a recently discovered solid-to-solid conversion process using a laser to heat a glass to its crystallization temperature but keeping it below the melting temperature. Such rotating lattice single (RLS) crystals are found, but only as spherulitic grains too small for systematic characterization or practical application. Additionally, she is a Rossin Junior Engineering Fellow, President of Eta Kappa Nu, Vice President of the IEEE student chapter and is a recipient of the Joseph C. Gabuzda Memorial Award for outstanding achievement in Electrical Engineering at Lehigh.Defying the requirements of translational periodicity in 3D, rotation of the lattice orientation within an otherwise single crystal provides a new form of solid. For this research she has received the Clare Boothe Luce Research Scholarship and Honorable Mention for her presentation at the David and Lorraine Freed Undergraduate Research Symposium in 2018. She began researching under the guidance of Professor Jonathan Wierer the summer after her sophomore year and plans to continue past receiving her bachelors by pursuing a PhD in the field. Rebecca Lentz is a senior studying electrical engineering at Lehigh University with a focus in semiconductor materials. The structure is designed for single-mode propagation of blue laser light (λ=405 nm), but could potentially guide light in the infrared spectrum, if designed with the proper dimensions. This air/GaN/AlInO waveguide is simulated using COMSOL multiphysics modeling software to determine mode characteristics and dimensional requirements. The AlInN is then oxidized laterally, beginning on the exposed AlInN and proceeding underneath the GaN core to create the AlInO lower cladding. This is followed by a thin GaN core layer which is then post-growth patterned and etched to form waveguiding strips. To produce the waveguiding structure, a thick layer (> 200 nm) of AlxIn1-xN is grown lattice matched (x~0.82) on a GaN layer by metalorganic chemical vapor deposition (MOCVD). This AlInO has a refractive index of n ~ 1.7 at λ=405 nm, making it ideal as a cladding layer for GaN, which has a refractive index of n ~ 2.4. This process uses wet thermal oxidation (H2O/N2 at 800 - 900 ☌) to form dense, insulating, and thick AlInO. Here a new oxidation process is used to transform AlInN to AlInO and form waveguides in III-nitride semiconductors. An analog semiconductor/buried oxide waveguide has yet to be demonstrated for III-nitrides. PICs require routing of the photonic signals which is, for example, accomplished in Si-based PICs using a Silicon-on-insulator waveguiding structure. These speeds can be enhanced further, as shown in other material systems, by using waveguides and modulators to form photonic integrated circuits (PIC). ![]() VLC can be accomplished using either light-emitting diodes (LEDs) or laser diodes (LDs), the latter offering faster modulation speeds due to stimulated emission. A more nascent application is III-nitride waveguides which have potential for various applications such as nonlinear optics, quantum photonics, and visible light communications (VLC). Gallium Nitride (GaN) is most commonly and successfully used for light-emitters, high- speed transistors, and power devices.
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