Research

Projects

Fourier Transform Infrared Spectroscopy to study Sequential Infiltration Synthesis (SIS)

In this work sequential infiltration synthesis (SIS) a modified atomic layer deposition method in polymeric materials are studied using in situ Fourier transform infrared (FTIR) spectroscopy. We study in situ Fourier transform infrared (FTIR) spectroscopy during Al₂O₃ and TiO₂ SIS in different polymers to understand the reaction dynamics between these polymers and the Al₂O₃ and TiO₂ precursors. The goal is to provide insight into the variety of mechanisms involved in polymer-inorganic precursor interactions during BCP lithography, which is currently an expanding nanopatterning technology. Understanding the reaction dynamics between these polymer-metal precursor pairs for superior, inexpensive and large-scale inorganic oxide synthesis is essential. In collaboration with Argonne National Laboratory we are trying to understand these mechanism.

Image of in situ fourier transform infrared specroscopy graph to understand the reaction dynamics

In situ FTIR to understand the reaction dynamics

Oxide Nanopatterns

Inorganic oxides such as TiO2 and ZnO are highly promising semiconductor material for various applications such as photo catalysis, water splitting, solar cells, super capacitors and lithium-ion batteries. In this project we explore the nanostructures fabrication of three commonly used oxides in optoelectronics applications TiO2, Al2O3 and ZnO using BCP as a template. Recently we demonstrated TiO2 nanodots of sub-50 nm dimension using BCP cylindrical nanostructures as template. PLD which is commonly used as a thin film deposition technique is used as inorganic oxide deposition method. In this approach, the PLD at room temperature and in a vacuum has been used. Since combining self-assembled BCP template in inorganic nanostructure fabrication requires a low-temperature (approximately 100°C or less) inorganic deposition process to avoid polymer degradation, in this work, we have used room temperature PLD method to deposit TiO2. Other oxide deposition method we use are chemical solution deposition and atomic layer deposition (ALD). We characterize the BCP and oxide nanostructures using scanning electron microscopy (SEM) and atomic force microscopy (AFM) images, X-ray photoelectron spectroscopy (XPS), Xray diffraction (XRD), and photoluminescence (PL) spectroscopy. We are continuously working on improving overall morphological shape and quality of different oxides.
Block Copolymer Templated Fabrication of TiO₂ Nanodot Films Using Pulsed Laser Deposition, K Pandey, K Ghosh, U Manna, M BiswasThe Journal of Physical Chemistry C 122 (28), 16325-16332 (2018)

Image of Schematic of the titanium dioxide Fabrication Process

Schematic of the Fabrication Process

Metal Nanoparticles

The spherical and anisotropic nanostructures of noble metals are of great interest for plasmonic applications, due to the possibility of tuning the localized surface plasmon resonance (LSPR) across the UV–visible–near infrared (UV–vis-NIR) without sacrificing the linewidth, as well as achieving larger local field enhancement. In our group we explore simple and promising fabrication method of gold nanoparticle films using polystyrene-b-poly(2vinylpyridine) (PS-b-P2VP) block copolymers (BCPs) micelles as a template. We fabricate gold nanostructures of various shapes, such as sphere, octahedron, decahedron, tetrahedron, triangles, and triangular prism. We are also studying the optical and emission and magnetic resonance properties of these Au nanoparticle films at ISU Physics Department in collaboration with Dr. Uttam Manna. We are currently looking into the possibility of controlled fabrication of low dimension (<10 nm) spherical film and of anisotropic nanoparticles with less heterogeneity in shape and size.

Block-copolymer assisted fabrication of anisotropic plasmonic nanostructures, C Gunder, PK Dhara, U Manna, M BiswasNanotechnology 29 (35), 355303 (2018)

Image of gold nanoparticles of different shapes using BCP micelle template

Au nanoparticles of different shapes using BCP micelle template

Si Nanoparticles Synthesis

In this ongoing project we are fabricating colloidal spherical Silicon nanoparticles of 50-250 nm of size for optical applications. We are collaborating with Dr. Uttam Manna at ISU and Dr. Norbert Scherer at University of Chicago to study the optical characteristics of these nanoparticles.