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Papers by Aniruddha Dutta

Research paper thumbnail of Controlling formation of gold nanoparticles generated in situ at a polymeric surface

This work shows that in situ reduction of metal ions bound at a polymer surface can form nanopart... more This work shows that in situ reduction of metal ions bound at a polymer surface can form nanoparticles within the polymer matrix as well as at the interface, and the size and distribution of nanoparticles between the interface and subsurface depends upon the choice of reagents and reaction conditions. Tetrachloroaurate ions were bound to cross-linked SU-8 films that were functionalized using a variety of multi-functional amines, then reduced using one of several reagents. Reduction using sodium borohydride or sodium citrate generates bands of interspersed gold nanoparticles as much as 40 nm deep within the polymer, indicating that both the Au ions and the reducing agent can penetrate the surface enabling formation of nanoparticles within the polymer matrix. Nanoparticle formation can be confined nearer to the polymer interface by reducing with hydroquinone, or by processing the polymer film in aqueous media using high molecular-weight multifunctional amines that confine the gold ions at the interface.

Research paper thumbnail of Interfacial Atomic Number Contrast in Thick TEM samples

Research paper thumbnail of Simulation of incoherent scattering in High-Angle Annular Dark-Field Scanning Electron Microscopy

A quantitative method to simulate the electron scattering intensities in Scanning Transmission El... more A quantitative method to simulate the electron scattering intensities in Scanning Transmission Electron Microscopy (STEM) for High-Angle Annular Dark-Field (HAADF) detectors is presented. A HAADF detector in a 300 kV transmission electron microscope collects electrons scattered to high angles with its intensity nearly proportional to the sample thickness and increasing with atomic number. Multislice simulations in Python 2.7 are used to calculate the scattering cross sections and the final intensity of the electron beam after multiple scattering events and for comparison with experimental results.

Research paper thumbnail of Structural, optical and electronic properties of Magnetron sputtered Si and Ge thin films

We report the results of GIXRR, UV-VIS NIR and XPS measurements on Si and Ge thin films of variou... more We report the results of GIXRR, UV-VIS NIR and XPS measurements on Si and Ge thin films of various thicknesses. While GIXRR measurements show no presence of oxide on the top of these films, XPS measurements show small amount of oxides. Also a sharp increase in surface roughness is seen with thickness in agreement with the columnar growth of films. In contrast, In case of Si films, oxide is present even inside the layers but in a very small amount and is not detected in GIXRR/absorption measurements

Research paper thumbnail of Nanoscale characterization of gold nanoparticles created by in situ reduction at a polymeric surface

Journal of Microscopy 251(1) 27-34, 2013, Apr 12, 2013

Transmission Electron Microscopy is used as a quantitative method to measure the shapes, sizes an... more Transmission Electron Microscopy is used as a quantitative method to measure the shapes, sizes and volumes of gold nanoparticles created at a polymeric surface by three different in situ synthesis methods. The atomic number contrast (Z-contrast) imaging technique reveals nanoparticles which are formed on the surface of the polymer. However, with certain reducing agents, the gold nanoparticles are additionally found up to 20 nm below the polymer surface. In addition, plan-view high-angle annular dark-field scanning transmission electron microscopy images were statistically analyzed on one sample to measure the volume, height and effective diameter of the gold nanoparticles and their size distributions. Depth analysis from high-angle annular dark-field scanning transmission electron microscopy micrographs also gives information on the dominant shape of the nanoparticles.

Research paper thumbnail of Quantitative Measurement of Volumes for Nanoparticles by High-Angle Annular Dark-Field Scanning Transmission Electron Microscopy

Microscopy and Microanalysis 16(S2) 1764-65, Jul 1, 2010

A quantitative method to determine sample thicknesses in Transmission Electron Microscopy (TEM) u... more A quantitative method to determine sample thicknesses in Transmission Electron Microscopy (TEM) using the Scanning (STEM) mode is presented. A High-Angle Annular Dark-Field (HAADF) detector collects electrons scattered to high angles with its intensity proportional to the sample thickness and increasing with atomic number. Multilayered samples provided by TriQuint Semiconductors in Apopka (FL) are used for calibration yielding data on the interaction cross section per atom.

Research paper thumbnail of Chemical bath deposition of SnO< sub> 2</sub> and Cd< sub> 2</sub> SnO< sub> 4</sub> thin films

A new approach of chemical bath deposition (CBD) of SnO2 thin films is reported. Films with a 0.2... more A new approach of chemical bath deposition (CBD) of SnO2 thin films is reported. Films with a 0.2 μm thickness are obtained using the multi-dip deposition approach with a deposition time as little as 8–10min for each dip. The possibility of fabricating a transparent conducting oxide layer of Cd2SnO4 thin films using CBD is investigated through successive layer deposition of CBD-SnO2 and CBD-CdO films, followed by annealing at different temperatures.

Research paper thumbnail of Investigation of chemical bath deposition of CdO thin films using three different complexing agents

Chemical bath deposition of CdO thin films using three different complexing agents, namely ammoni... more Chemical bath deposition of CdO thin films using three different complexing agents, namely ammonia, ethanolamine, and methylamine is investigated. CdSO4 is used as Cd precursor, while H2O2 is used as an oxidation agent. As-grown films are mainly cubic CdO2, with some Cd (OH) 2 as well as CdO phases being detected. Annealing at 400° C in air for 1h transforms films into cubic CdO. The calculated optical band gap of as-grown films is in the range of 3.37–4.64 eV. Annealed films have a band gap of about 2.53 eV.

Research paper thumbnail of Morphologies from slippery ballistic deposition model: A bottom-up approach for nanofabrication

Physical Review E, Jan 1, 2011

We report pattern formation using a slippery ballistic deposition (SBD) model where growth germin... more We report pattern formation using a slippery ballistic deposition (SBD) model where growth germinates from a single site or from sites distributed periodically on a lattice. By changing the sticking probability ps and choosing systems with different lattice constants and symmetries, we demonstrate that a variety of patterns can be generated. These patterns can be further used as scaffolds for nanofabrication. We also demonstrate that by choosing a lateral sticking probability pl at the base that is different than ps, one can control both the early and late time morphologies originating from a seed. Furthermore, we indicate a possible generalization of preparing patterns to higher dimensions that in principle can have potential technological applications for preparing grooves and scaffolds of specific shapes and periodicities.

Conference Presentations by Aniruddha Dutta

Research paper thumbnail of Nano-scale characterization of the formation of silver layers during electroless deposition on polymeric surfaces

We report here a quantitative method of Transmission Electron Microscopy (TEM) to measure the sha... more We report here a quantitative method of Transmission Electron Microscopy (TEM) to measure the shapes, sizes and volumes of nanoparticles which are responsible for their properties. Gold nanoparticles (Au NPs) acting as nucleating agents for the electroless deposition of silver NPs on SU-8 polymers were analyzed in this project. The atomic-number contrast (Z-contrast) imaging technique reveals the height and effective diameter of each Au NP and a volume distribution is obtained. Varying the reducing agents produced Au NPs of different sizes which were found both on the polymer surface and in some cases buried several nanometers below the surface. The morphology of Au NPs is an important factor for systems that use surface-bound nanoparticles as nucleation sites as in electroless metallization. Electrolessly deposited silver layers reduced by hydroquinone on SU-8 polymer are analyzed in this project.

Research paper thumbnail of Controlling formation of gold nanoparticles generated in situ at a polymeric surface

This work shows that in situ reduction of metal ions bound at a polymer surface can form nanopart... more This work shows that in situ reduction of metal ions bound at a polymer surface can form nanoparticles within the polymer matrix as well as at the interface, and the size and distribution of nanoparticles between the interface and subsurface depends upon the choice of reagents and reaction conditions. Tetrachloroaurate ions were bound to cross-linked SU-8 films that were functionalized using a variety of multi-functional amines, then reduced using one of several reagents. Reduction using sodium borohydride or sodium citrate generates bands of interspersed gold nanoparticles as much as 40 nm deep within the polymer, indicating that both the Au ions and the reducing agent can penetrate the surface enabling formation of nanoparticles within the polymer matrix. Nanoparticle formation can be confined nearer to the polymer interface by reducing with hydroquinone, or by processing the polymer film in aqueous media using high molecular-weight multifunctional amines that confine the gold ions at the interface.

Research paper thumbnail of Interfacial Atomic Number Contrast in Thick TEM samples

Research paper thumbnail of Simulation of incoherent scattering in High-Angle Annular Dark-Field Scanning Electron Microscopy

A quantitative method to simulate the electron scattering intensities in Scanning Transmission El... more A quantitative method to simulate the electron scattering intensities in Scanning Transmission Electron Microscopy (STEM) for High-Angle Annular Dark-Field (HAADF) detectors is presented. A HAADF detector in a 300 kV transmission electron microscope collects electrons scattered to high angles with its intensity nearly proportional to the sample thickness and increasing with atomic number. Multislice simulations in Python 2.7 are used to calculate the scattering cross sections and the final intensity of the electron beam after multiple scattering events and for comparison with experimental results.

Research paper thumbnail of Structural, optical and electronic properties of Magnetron sputtered Si and Ge thin films

We report the results of GIXRR, UV-VIS NIR and XPS measurements on Si and Ge thin films of variou... more We report the results of GIXRR, UV-VIS NIR and XPS measurements on Si and Ge thin films of various thicknesses. While GIXRR measurements show no presence of oxide on the top of these films, XPS measurements show small amount of oxides. Also a sharp increase in surface roughness is seen with thickness in agreement with the columnar growth of films. In contrast, In case of Si films, oxide is present even inside the layers but in a very small amount and is not detected in GIXRR/absorption measurements

Research paper thumbnail of Nanoscale characterization of gold nanoparticles created by in situ reduction at a polymeric surface

Journal of Microscopy 251(1) 27-34, 2013, Apr 12, 2013

Transmission Electron Microscopy is used as a quantitative method to measure the shapes, sizes an... more Transmission Electron Microscopy is used as a quantitative method to measure the shapes, sizes and volumes of gold nanoparticles created at a polymeric surface by three different in situ synthesis methods. The atomic number contrast (Z-contrast) imaging technique reveals nanoparticles which are formed on the surface of the polymer. However, with certain reducing agents, the gold nanoparticles are additionally found up to 20 nm below the polymer surface. In addition, plan-view high-angle annular dark-field scanning transmission electron microscopy images were statistically analyzed on one sample to measure the volume, height and effective diameter of the gold nanoparticles and their size distributions. Depth analysis from high-angle annular dark-field scanning transmission electron microscopy micrographs also gives information on the dominant shape of the nanoparticles.

Research paper thumbnail of Quantitative Measurement of Volumes for Nanoparticles by High-Angle Annular Dark-Field Scanning Transmission Electron Microscopy

Microscopy and Microanalysis 16(S2) 1764-65, Jul 1, 2010

A quantitative method to determine sample thicknesses in Transmission Electron Microscopy (TEM) u... more A quantitative method to determine sample thicknesses in Transmission Electron Microscopy (TEM) using the Scanning (STEM) mode is presented. A High-Angle Annular Dark-Field (HAADF) detector collects electrons scattered to high angles with its intensity proportional to the sample thickness and increasing with atomic number. Multilayered samples provided by TriQuint Semiconductors in Apopka (FL) are used for calibration yielding data on the interaction cross section per atom.

Research paper thumbnail of Chemical bath deposition of SnO< sub> 2</sub> and Cd< sub> 2</sub> SnO< sub> 4</sub> thin films

A new approach of chemical bath deposition (CBD) of SnO2 thin films is reported. Films with a 0.2... more A new approach of chemical bath deposition (CBD) of SnO2 thin films is reported. Films with a 0.2 μm thickness are obtained using the multi-dip deposition approach with a deposition time as little as 8–10min for each dip. The possibility of fabricating a transparent conducting oxide layer of Cd2SnO4 thin films using CBD is investigated through successive layer deposition of CBD-SnO2 and CBD-CdO films, followed by annealing at different temperatures.

Research paper thumbnail of Investigation of chemical bath deposition of CdO thin films using three different complexing agents

Chemical bath deposition of CdO thin films using three different complexing agents, namely ammoni... more Chemical bath deposition of CdO thin films using three different complexing agents, namely ammonia, ethanolamine, and methylamine is investigated. CdSO4 is used as Cd precursor, while H2O2 is used as an oxidation agent. As-grown films are mainly cubic CdO2, with some Cd (OH) 2 as well as CdO phases being detected. Annealing at 400° C in air for 1h transforms films into cubic CdO. The calculated optical band gap of as-grown films is in the range of 3.37–4.64 eV. Annealed films have a band gap of about 2.53 eV.

Research paper thumbnail of Morphologies from slippery ballistic deposition model: A bottom-up approach for nanofabrication

Physical Review E, Jan 1, 2011

We report pattern formation using a slippery ballistic deposition (SBD) model where growth germin... more We report pattern formation using a slippery ballistic deposition (SBD) model where growth germinates from a single site or from sites distributed periodically on a lattice. By changing the sticking probability ps and choosing systems with different lattice constants and symmetries, we demonstrate that a variety of patterns can be generated. These patterns can be further used as scaffolds for nanofabrication. We also demonstrate that by choosing a lateral sticking probability pl at the base that is different than ps, one can control both the early and late time morphologies originating from a seed. Furthermore, we indicate a possible generalization of preparing patterns to higher dimensions that in principle can have potential technological applications for preparing grooves and scaffolds of specific shapes and periodicities.

Research paper thumbnail of Nano-scale characterization of the formation of silver layers during electroless deposition on polymeric surfaces

We report here a quantitative method of Transmission Electron Microscopy (TEM) to measure the sha... more We report here a quantitative method of Transmission Electron Microscopy (TEM) to measure the shapes, sizes and volumes of nanoparticles which are responsible for their properties. Gold nanoparticles (Au NPs) acting as nucleating agents for the electroless deposition of silver NPs on SU-8 polymers were analyzed in this project. The atomic-number contrast (Z-contrast) imaging technique reveals the height and effective diameter of each Au NP and a volume distribution is obtained. Varying the reducing agents produced Au NPs of different sizes which were found both on the polymer surface and in some cases buried several nanometers below the surface. The morphology of Au NPs is an important factor for systems that use surface-bound nanoparticles as nucleation sites as in electroless metallization. Electrolessly deposited silver layers reduced by hydroquinone on SU-8 polymer are analyzed in this project.