Daniel Stieler - Academia.edu (original) (raw)

Papers by Daniel Stieler

Research paper thumbnail of Growth and Electronic Properties of Nanocrystalline Si

Abstract Nanocrystalline Silicon is an important electronic materials for solar cells, for displa... more Abstract Nanocrystalline Silicon is an important electronic materials for solar cells, for display devices and for sensors. In this paper, we discuss the influence of ions on the growth and properties of thenanocrystalline Si: H material. Using a unique growth geometry, ...

Research paper thumbnail of Characterization of defect cavities and channel-drop filters in the three dimensional woodpile photonic crystal

Photonic crystals (PCs) are devices with the ability to confine electromagnetic (EM) waves due to... more Photonic crystals (PCs) are devices with the ability to confine electromagnetic (EM) waves due to their EM bandgap. The three-dimensional woodpile PC studied in this dissertation is appealing because unlike its two-dimensional counter parts, it is able to confine and guide EM waves in all three dimensions. This dissertation examines the fundamental properties of resonant cavities and use of cavities and waveguides (WGs) to create channel-drop filters in the woodpile PC. Resonant cavities are a major building block of photonic integrated circuits devices. Therefore it is important to understand how to control the properties of their resonant modes, such as quality factor (Q), resonant frequency, magnitude, and mode shape. This dissertation examines the effects of incident EM wave polarization, cavity size, cavity permittivity, cavity confinement, material loss, and lattice disorder on the properties of the resonant mode. Channel-drop filters are devices that can be used to transfer EM energy of a specific frequency from one WG to another. Channel-drop filters could be used to optically add or remove a specific carrier frequency from a fiber optic cable transporting many carrier frequencies. Channel-drop filters made from a PC are able to perform this task completely optically. This would speed up the optical network since conversion of the optical signal to an electronic signal is not required. In this dissertation six channel-drop filter configurations are examined. These structures are made both in a single stacking layer and separated by many layers. Five of the structures demonstrated good energy transfer from the input (bus) WG to the output (drop) WG. The ability to control the frequency and Q of the transferred EM mode is achieved by varying the cavity size and confinement.

Research paper thumbnail of Advances in roll-to-roll imprint lithography for display applications

A solution to the problems of roll-to-roll lithography on flexible substrates is presented. We ha... more A solution to the problems of roll-to-roll lithography on flexible substrates is presented. We have developed a roll-toroll imprint lithography technique to fabricate active matrix transistor backplanes on flexible webs of polyimide that have a blanket material stack of metals, dielectrics, and semiconductors. Imprint lithography produces a multi-level 3- dimensional mask that is then successively etched to pattern the underlying layers into the desired structures. This process, Self-Aligned Imprint Lithography (SAIL), solves the layer-to-layer alignment problem because all masking levels are created with one imprint step. The processes and equipment required for complete roll-to-roll SAIL fabrication will be described. Emphasis will be placed on the advances in the roll-to-roll imprint process which have enabled us to produce working transistor arrays.

Research paper thumbnail of Fine tuning resonant frequencies for a single cavity defect in three-dimensional layer-by-layer photonic crystal

Optics Express, 2008

The resonant frequencies of a single cavity embedded in the three-dimensional layer-by-layer phot... more The resonant frequencies of a single cavity embedded in the three-dimensional layer-by-layer photonic crystal are studied with microwave experiments and transfer-scattering matrix method simulations. The effects of the number of cladding layers and the size of the embedded cavity on resonant frequencies and Q values are carefully examined. The fine increments of cavity size indicate a new pattern of relation between resonant frequencies and cavity sizes.

Research paper thumbnail of A planar four-port channel drop filter in the three-dimensional woodpile photonic crystal

Optics Express, 2009

A compact planar channel four-port drop filter is developed experimentally and theoretically in t... more A compact planar channel four-port drop filter is developed experimentally and theoretically in the three-dimensional woodpile photonic crystal having a complete band gap. This consists of two waveguides separated by a defect in a single layer of the photonic crystal. Frequencies for channel dropping can be tuned throughout the band gap, by changing the size of the defect. Quality factors of ~1000 were measured. Simulations demonstrate directional energy transfer between the input and out put waveguides, through excitation of fields in the defect region. The planar nature of the filter is much more amenable to fabrication at optical length wavelengths.

Research paper thumbnail of Effects of defect permittivity on resonant frequency and mode shape in the three-dimensional woodpile photonic crystal

Journal of Applied Physics, 2009

Tuning the resonant frequency of a 1 uc defect across the bandgap of a three-dimensional woodpile... more Tuning the resonant frequency of a 1 uc defect across the bandgap of a three-dimensional woodpile photonic crystal (PC) was achieved by altering the defect's permittivity. Experiments were performed at microwave frequencies and calculations were made using the transfer-scattering matrix method. Defect permittivity was varied by using solid materials of different permittivities or by constructing structures smaller than a lattice

Research paper thumbnail of Electron mobility in nanocrystalline silicon devices

Journal of Applied Physics, 2006

Electron mobility in the growth direction was measured using space charge limited current techniq... more Electron mobility in the growth direction was measured using space charge limited current techniques in device-type nin structure nanocrystalline Si: H and nanocrystalline Ge: H structures. The films were grown on stainless steel foil using either hot wire or remote ...

Research paper thumbnail of Growth chemistry of nanocrystalline silicon and germanium films

Journal of Non-crystalline Solids, 2006

We report on the growth of nanocrystalline Si:H and Ge:H films. The films were grown using plasma... more We report on the growth of nanocrystalline Si:H and Ge:H films. The films were grown using plasma deposition and hot wire chemical growth techniques. Conditions such as pressure, temperature and hydrogen dilution were systematically varied. It is shown that excessive hydrogen dilution during growth leads to smaller grains in nanocrystalline Si and Ge. Films with very large grains (56 nm) could be obtained using hot wire growth techniques under appropriate conditions of growth. From the data, it is concluded that the natural growth direction for the films is h2 2 0i, and that excessive bonded hydrogen leads to smaller grains.

Research paper thumbnail of Growth and Electronic Properties of Nanocrystalline Si

Abstract Nanocrystalline Silicon is an important electronic materials for solar cells, for displa... more Abstract Nanocrystalline Silicon is an important electronic materials for solar cells, for display devices and for sensors. In this paper, we discuss the influence of ions on the growth and properties of thenanocrystalline Si: H material. Using a unique growth geometry, ...

Research paper thumbnail of Characterization of defect cavities and channel-drop filters in the three dimensional woodpile photonic crystal

Photonic crystals (PCs) are devices with the ability to confine electromagnetic (EM) waves due to... more Photonic crystals (PCs) are devices with the ability to confine electromagnetic (EM) waves due to their EM bandgap. The three-dimensional woodpile PC studied in this dissertation is appealing because unlike its two-dimensional counter parts, it is able to confine and guide EM waves in all three dimensions. This dissertation examines the fundamental properties of resonant cavities and use of cavities and waveguides (WGs) to create channel-drop filters in the woodpile PC. Resonant cavities are a major building block of photonic integrated circuits devices. Therefore it is important to understand how to control the properties of their resonant modes, such as quality factor (Q), resonant frequency, magnitude, and mode shape. This dissertation examines the effects of incident EM wave polarization, cavity size, cavity permittivity, cavity confinement, material loss, and lattice disorder on the properties of the resonant mode. Channel-drop filters are devices that can be used to transfer EM energy of a specific frequency from one WG to another. Channel-drop filters could be used to optically add or remove a specific carrier frequency from a fiber optic cable transporting many carrier frequencies. Channel-drop filters made from a PC are able to perform this task completely optically. This would speed up the optical network since conversion of the optical signal to an electronic signal is not required. In this dissertation six channel-drop filter configurations are examined. These structures are made both in a single stacking layer and separated by many layers. Five of the structures demonstrated good energy transfer from the input (bus) WG to the output (drop) WG. The ability to control the frequency and Q of the transferred EM mode is achieved by varying the cavity size and confinement.

Research paper thumbnail of Advances in roll-to-roll imprint lithography for display applications

A solution to the problems of roll-to-roll lithography on flexible substrates is presented. We ha... more A solution to the problems of roll-to-roll lithography on flexible substrates is presented. We have developed a roll-toroll imprint lithography technique to fabricate active matrix transistor backplanes on flexible webs of polyimide that have a blanket material stack of metals, dielectrics, and semiconductors. Imprint lithography produces a multi-level 3- dimensional mask that is then successively etched to pattern the underlying layers into the desired structures. This process, Self-Aligned Imprint Lithography (SAIL), solves the layer-to-layer alignment problem because all masking levels are created with one imprint step. The processes and equipment required for complete roll-to-roll SAIL fabrication will be described. Emphasis will be placed on the advances in the roll-to-roll imprint process which have enabled us to produce working transistor arrays.

Research paper thumbnail of Fine tuning resonant frequencies for a single cavity defect in three-dimensional layer-by-layer photonic crystal

Optics Express, 2008

The resonant frequencies of a single cavity embedded in the three-dimensional layer-by-layer phot... more The resonant frequencies of a single cavity embedded in the three-dimensional layer-by-layer photonic crystal are studied with microwave experiments and transfer-scattering matrix method simulations. The effects of the number of cladding layers and the size of the embedded cavity on resonant frequencies and Q values are carefully examined. The fine increments of cavity size indicate a new pattern of relation between resonant frequencies and cavity sizes.

Research paper thumbnail of A planar four-port channel drop filter in the three-dimensional woodpile photonic crystal

Optics Express, 2009

A compact planar channel four-port drop filter is developed experimentally and theoretically in t... more A compact planar channel four-port drop filter is developed experimentally and theoretically in the three-dimensional woodpile photonic crystal having a complete band gap. This consists of two waveguides separated by a defect in a single layer of the photonic crystal. Frequencies for channel dropping can be tuned throughout the band gap, by changing the size of the defect. Quality factors of ~1000 were measured. Simulations demonstrate directional energy transfer between the input and out put waveguides, through excitation of fields in the defect region. The planar nature of the filter is much more amenable to fabrication at optical length wavelengths.

Research paper thumbnail of Effects of defect permittivity on resonant frequency and mode shape in the three-dimensional woodpile photonic crystal

Journal of Applied Physics, 2009

Tuning the resonant frequency of a 1 uc defect across the bandgap of a three-dimensional woodpile... more Tuning the resonant frequency of a 1 uc defect across the bandgap of a three-dimensional woodpile photonic crystal (PC) was achieved by altering the defect's permittivity. Experiments were performed at microwave frequencies and calculations were made using the transfer-scattering matrix method. Defect permittivity was varied by using solid materials of different permittivities or by constructing structures smaller than a lattice

Research paper thumbnail of Electron mobility in nanocrystalline silicon devices

Journal of Applied Physics, 2006

Electron mobility in the growth direction was measured using space charge limited current techniq... more Electron mobility in the growth direction was measured using space charge limited current techniques in device-type nin structure nanocrystalline Si: H and nanocrystalline Ge: H structures. The films were grown on stainless steel foil using either hot wire or remote ...

Research paper thumbnail of Growth chemistry of nanocrystalline silicon and germanium films

Journal of Non-crystalline Solids, 2006

We report on the growth of nanocrystalline Si:H and Ge:H films. The films were grown using plasma... more We report on the growth of nanocrystalline Si:H and Ge:H films. The films were grown using plasma deposition and hot wire chemical growth techniques. Conditions such as pressure, temperature and hydrogen dilution were systematically varied. It is shown that excessive hydrogen dilution during growth leads to smaller grains in nanocrystalline Si and Ge. Films with very large grains (56 nm) could be obtained using hot wire growth techniques under appropriate conditions of growth. From the data, it is concluded that the natural growth direction for the films is h2 2 0i, and that excessive bonded hydrogen leads to smaller grains.