Silicon Germanium, SiGe, is an important emerging semiconductor material. In order to optimize growth techniques for SiGe production, such as Liquid Phase Diffusion, LPD, or Melt Replenishment Czochralski, a good understanding of the transport phenomena in the melt is required. In the context of the Liquid Phase Diffusion growth technique, the transport phenomena of silicon in a silicon-germanium melt has been explored. Experiments isolating the dissolution and transport of silicon into a germanium melt have been conducted under a variety of flow conditions. Preliminary modeling of these experiments has also been conducted and agreement with experiments has been shown. In addition, full LPD experiments have also been conducted under varying flow conditions. Altered flow conditions were achieved through the application of a variety of magnetic fields. Through the experimental and modeling work better understanding of the transport mechanisms at work in a silicon-germanium melt has been achieved.
Silicon has made modern integrated circuit technology possible. As MOSFET gate lengths are scaled to 22nm and beyond, it has become apparent that new materials must be introduced to the silicon-based CMOS process for improved performance and functionality. This dissertation begins with a review of the MOSFET leakage current problem and presents one potential solution: Band-to-Band Tunneling (BTBT) transistors, which have the potential for steeper subthreshold slopes because they do not have the fundamental 'kT/q' limit in the rate at which conventional MOSFETs can be turned on or off. It is clear that these devices must be fabricated in materials with smaller bandgaps for improved performance. Silicon Germanium (SiGe) is one possible material system that could be used to fabricate enhanced BTBT transistors. Rapid Melt Growth (RMG) is a technique that has been used to recrystallize materials on Si substrates. RMG, however, has not previously been applied to SiGe, a binary alloy with large separation in the liquidus-solidus curve in its phase diagram. The development of process and experimental results for obtaining SiGe-on-insulator (SGOI) from bulk Si substrates through RMG are presented. The theory of RMG is analyzed and compositional profiles obtained during RMG of SiGe are modeled to understand why we were able to obtain high quality lateral compositionally graded SGOI substrates. The success of RMG SiGe suggests that the RMG technique can also be applied to III-V ternary and quaternary compounds with similar pseudo-binary phase diagrams. This opens up a wide range of material possibilities with the potential for novel applications in heterogeneous integration and 3-D device technology.
Materials processing and manufacturing are fields of growing importance whereby transport phenomena play a central role in many of the applications. This volume is one of the first collections of contributions on thesubject. The five papers cover a wide variety of applications
Volume IIIA Basic Techniques Handbook of Crystal Growth, Second Edition Volume IIIA (Basic Techniques), edited by chemical and biological engineering expert Thomas F. Kuech, presents the underpinning science and technology associated with epitaxial growth as well as highlighting many of the chief and burgeoning areas for epitaxial growth. Volume IIIA focuses on major growth techniques which are used both in the scientific investigation of crystal growth processes and commercial development of advanced epitaxial structures. Techniques based on vacuum deposition, vapor phase epitaxy, and liquid and solid phase epitaxy are presented along with new techniques for the development of three-dimensional nano-and micro-structures. Volume IIIB Materials, Processes, and Technology Handbook of Crystal Growth, Second Edition Volume IIIB (Materials, Processes, and Technology), edited by chemical and biological engineering expert Thomas F. Kuech, describes both specific techniques for epitaxial growth as well as an array of materials-specific growth processes. The volume begins by presenting variations on epitaxial growth process where the kinetic processes are used to develop new types of materials at low temperatures. Optical and physical characterizations of epitaxial films are discussed for both in situ and exit to characterization of epitaxial materials. The remainder of the volume presents both the epitaxial growth processes associated with key technology materials as well as unique structures such as monolayer and two dimensional materials. Volume IIIA Basic Techniques Provides an introduction to the chief epitaxial growth processes and the underpinning scientific concepts used to understand and develop new processes. Presents new techniques and technologies for the development of three-dimensional structures such as quantum dots, nano-wires, rods and patterned growth Introduces and utilizes basic concepts of thermodynamics, transport, and a wide cross-section of kinetic processes which form the atomic level text of growth process Volume IIIB Materials, Processes, and Technology Describes atomic level epitaxial deposition and other low temperature growth techniques Presents both the development of thermal and lattice mismatched streams as the techniques used to characterize the structural properties of these materials Presents in-depth discussion of the epitaxial growth techniques associated with silicone silicone-based materials, compound semiconductors, semiconducting nitrides, and refractory materials
This first volume provides the basic matters needed for understanding the thermophysical properties of metallic liquids and for developing reliable models to accurately predict the thermophysical properties of almost all metallic elements in the liquid state, together with methods for quantitative assessment of models/equations. The authors also review the structure of metallic liquids, which is based on the theory of liquids, density, volume expansivity, thermodynamic properties (evaporation enthalpy, vapour pressure, heat capacity), sound velocity, surface tension, viscosity, diffusion, and electrical and thermal conductivities. Finally, the essential points of methods used for measuring these experimental data are presented.
Elemental semiconductors like silicon and germanium have been used since the beginning of the electronics industry. Silicon has dominated research and production and thus silicon based devices can be produced at the lowest cost using the most mature technology. While dopants can be used to tailor the electric properties of the semiconductor within certain limits, more flexibility is gained using compound semiconductors such as silicon-germanium. The electric properties of a compound semiconductor are highly dependant on the composition, which in turn is influenced by the dissolution reaction and flow characteristics during the growth process. Liquid phase diffusion (LPD) is a solution growth technique that has been proposed to grow silicon-germanium seed crystals for other growth techniques. The dissolution of silicon is a limiting factor for the growth rate in LPD and also Bridgman growth techniques. Investigation of the dissolution process is aimed at increasing the growth rate while still maintaining maximum uniformity of the crystal composition. To accomplish this, a static magnetic field was utilized in experiments done by Armour. The experimental results showed that a top seeded configuration without magnetic fields leads to a diffusion driven process and homogeneous dissolution, while the addition of a strong 0.8 Tesla magnetic field resulted in non-uniform and slightly increased dissolution. This work is complementary to the experimental investigation and aims to help understand the influence of magnetic fields on silicon dissolution. For this work, an OpenFOAM magnetohydrodynamics application including heat and species transport and three different magnetic force models has been developed and validated. The simulations done show that an isothermal state is reached within 90 seconds if no temperature gradient is imposed. Additional simulations with a temperature gradient helped to rule out a possible thermal leak in the experimental system, confirming that i.
