The amorphous to crystalline phase change is of great interest for the production and operation of phase change memory and germanium electronic devices. Phase change memory relies on the ability to differentiate between differences in optical or electrical properties between the amorphous and crystalline phases of a single material. Amorphous...
In this dissertation, the structure and electronic properties of multiple metal oxide thin films are characterized and presented. Prompt inorganic condensation (PIC) of metal-oxo and –hydroxo clusters was evaluated as a technique for making metal oxide clusters in two separate studies. The first focuses on the synthesis of lithium niobate...
Microscale continuous thin films or patterned conductive structures find applications in thin film electronics, energy generation and functional sensor systems. An emerging alternative to conventional vacuum based deposition of such structures is the additive deposition and sintering of conductive nanoparticles, to enable low temperature, low- cost and low energy fabrication....
Zinc Sulfide (ZnS) thin film, with a wide band gap, has been used for many applications, such as buffer layer for CIGS solar cells, light emitting diodes and thin film electroluminescent devices.
In this work, ZnS thin films were prepared using two different deposition processes. In the first method, ZnS...
Cobalt germanides have been widely studied as semiconductor contact materials, but recent theoretical studies suggest that they may also be excellent catalysts for methane steam reforming with stabilities and activities comparable to noble metal catalysts. In order to study the catalytic activity of cobalt germanides, it is critical to first...
Piezoelectric materials convert mechanical strain into a dielectric displacement, as well as the converse, allowing these materials to be used as sensors, actuators, and transducers. Currently, lead zirconate titanate (PZT) is the primary material used in these applications. Due to environmental toxicity and safety concerns associated with Pb, development of...
Polylactic acid (PLA), a renewable material, is used widely in a variety of commercial and specialty applications. However, certain limitations such as high temperature stability and brittleness limit its applicability. This problem is addressed by reinforcing PLA with a variety of materials but the process gives rise to different issues...
Advances in energy technologies and electronics have typically occurred through either heightened performance or cost reduction. This dissertation explores both routes through a series of fundamental material studies that may contribute to the enabling of next generation devices. Solution based syntheses and deposition of chemical products offer a low cost...
Current cadmium telluride and copper indium gallium diselenide thin-film solar cells
(TFSCs) utilize thick absorbers (2 - 4 μm). For efficient carrier extraction in these TFSCs,
the absorber layer requires high carrier mobilities and a long minority carrier lifetime, which
necessitates the use of a high purity, defect-free thin film....
Flexible electronics processing techniques were applied to integrate a glucose sensor with a hormone-delivery catheter in order to create a cheap and minimally invasive method for patients with type 1 diabetes to continually monitor and control their blood sugar levels. Ultimately, this work intends to move toward the development of...
The development of solution-based methods for deposition of different thin film material is presented as an alternative to high cost vacuum-based methods. For certain materials, vacuum techniques are unsuitable for processing. Additionally, vacuum-based processes present high capital costs associated with equipment, and slow processing times. Atmospheric pressure solution based techniques...
The motivation for undertaking this research was to increase the understanding of processing colloidal semiconductor nanocrystals and thin films metallic glasses to enable their wider application in future devices. This research covered two unique materials, lead selenide (PbSe) nanocrystals and thin film metallic glass alloy of zirconium copper aluminum nickel...
The atomic solid state energy (SSE) scale is introduced as a tool for inorganic materials design. The SSE scale is obtained by assessing an average electron affinity (EA) (for a cation) or an average ionization potential (IP) (for an anion) for each atom using data from compounds having that specific...
BiCuOSe and SnS are layered, moderate band gap (ε[subscript G] ≈ 1 eV) semiconductors that exhibit intrinsic p type conductivity. Doping of BiCuOSe with Ca results in a slight expansion of the lattice and an increase of the hole concentration from 10¹⁸ cm⁻³ to greater than 10²⁰ cm⁻³. The large...
Copper sulfides (Cu[subscript x]S) are compound semiconductor materials that exhibit considerable optical and electrical properties varying significantly as a function of the composition. Copper sulfide thin films can be used in many applications, such as solar control coatings, solar cells, photothermal conversion of solar energy, electroconductive coatings, and microwave shielding...
Pb(Zr₀.₅₂Ti₀.₄₈)O₃ (PZT) thin films are of interest for their large dielectric permittivity, ferroelectric, and piezoelectric properties. The material has been widely studied for use in high frequency transducers, multi-layered capacitors, and ferroelectric random access memory. Copper foils are an inexpensive, flexible substrate with a low resistivity which makes them ideal...
Piezoelectric materials have been widely used in electromechanical actuators, sensors, and ultrasonic transducers. Among these materials, lead zirconate titanate Pb(Zr[subscript 1‐x]Ti[subscript x])O₃ (PZT) has been primarily investigated due to its excellent piezoelectric properties. However, environmental concerns due to the toxicity of PbO have led to investigations into alternative materials systems....
The continuous microreactor-assisted solution deposition (MASD) process was used for the deposition of CdS thin films on fluorine-doped tin oxide (FTO) glass. The MASD system, including a T-junction micromixer and a microchannel heat exchanger is capable of isolating the homogeneous particle precipitation from the heterogeneous surface reaction. The results show...
Solid-state amorphous materials show amazing promise in thin-film electronics. The interface-to-bulk ratio of thin films makes interfacial chemistries of these systems of utmost importance. Thin films of amorphous metals, dielectrics and semiconductors have novel chemistries that are not only based upon their elemental constituent makeup, but also based upon the...
Pb(Zr,Ti)O₃ (PZT) is a very attractive material for use in piezoelectric-based microelectromechanical systems (MEMS) due to its high piezoelectric coefficients and ability for large displacements with relatively low applied fields (as compared to electrostatic-based MEMS). The piezoelectric effect is strongly anisotropic, thus it is very desirable to control the crystallographic...
Thin films are an enabling technology for a wide range of applications, from microprocessors to diffusion barriers. Nanolaminate thin films combine two (or more) materials in a layered structure to achieve performance that neither film could provide on its own. Atomic layer deposition (ALD) is a chemical vapor deposition technique...
Crystals of an incongruent-melting compound, Ba₃MgSi₂O₈, were grown by the flux method and its structure was determined by single crystal X-ray diffraction methods. Ba₃MgSi₂O₈ crystallizes in trigonal space group P-3[bar]m1 with a = 5.6123(3) Å, c = 7.2667(9) Å and Z = 1. Eu²⁺ ions prefer one crystallographic Ba site...
This dissertation outlines two approaches for improving the efficiency and reducing the cost of photovoltaic energy generation. First, the structures of known binary copper and iron compounds are used to choose the promising compositions Fe₂XS₄ (X = Si, Ge), Cu₃TaQ₄ (Q = Se, Te), and BaCuQ'F (Q' = S, Se,...