Graduation Term

Summer 2025

Degree Name

Master of Science (MS)

Department

Department of Chemistry

Committee Chair

Uttam Manna

Committee Member

Mahua Biswas

Committee Member

Jun-Hyun Kim

Abstract

The pursuit of advancements and miniaturization in science and technology has driven the exploration of lower dimensional materials to develop faster, more efficient, and cost-effective devices. In this regard, the fast-evolving field of semiconductor materials at nanoscale have come out with new avenues for high performance devices in major fields like optoelectronics. This thesis focuses on the fabrication of two distinct semiconductor nanomaterials using separate synthesis approaches for optoelectronic applications: (i) nanostructured patterns of the group III nitride material gallium nitride (GaN) were fabricated using a vapor-phase technique known as sequential infiltration synthesis (SIS), and (ii) spherical silicon nanoparticles were synthesized via a thermal disproportionation method at 1500 oC. Compared to the conventional nanofabrication techniques, SIS can produce high quality, scalable, well-ordered nitride materials with the focus on exploring their structural integrity, and optical responses. We have successfully used SIS technique for fabrication of gallium nitride using polystyrene-block-polymethylmethacrylate (PS-b-PMMA) and polystyrene-block-poly (α-caprolactone) (PS-b-PCL) block copolymers as the guiding templates. The fabricated nanopatterns were characterized using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and fourier transform infrared spectroscopy (FTIR). To investigate the optical response of the nanopatterns, UV–Vis spectroscopy was employed to measure the absorbance, followed by their photoluminescence emission measurements. Concurrently, high index dielectric spherical silicon nanoparticles were synthesized using high-temperature fabrication method (~1500 oC). In this method, a solid state disproportionate of Si nanoparticles embedded in silicon dioxide (SiO2) matrix was obtained after high temperature annealing at 1500 oC of silicon monoxide (SiO) powder followed by chemical etching of the SiO2 matrix using hydrofluoric acid (HF) to obtain colloidal Si nanoparticles. SEM images and measurement software were used to characterize the shape and size of these nanoparticles. We used UV-Vis spectroscopy to observe the extinction spectrum of the colloidal solution of nanoparticles and single particle vector spectroscopy to observe the scattering of particles. By integrating the observations, the goal was to identify and produce proto-type next generation devices for large scale industrial applications.

Access Type

Thesis-Open Access

DOI

https://doi.org/10.30707/ETD.1763755359.068753

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Available for download on Monday, September 10, 2029

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