In this paper, several new MOSFET devices, vertical MOSFET with L-shaped internal block layers (bVMOS), planar MOSFET with self-aligned internal block layers (bMOS), and Silicon-Germanium MOSFET with self-aligned internal block layers (bSGMOS) are presented. We use the sidewall spacer and etch back techniques to form the L-shaped internal block layers of bVMOS. They can suppress the short channel effects, diminish the parasitic capacitance, and reduce the leakage current cause by P-N junction between source/drain and body regions. They also provide a pass way to eliminate carriers and heat which generated by impact ionization resulting in suppression of floating-body effect and self-heating effect. In addition, we use Si3N4 cap layer upon gate as a hard mask, combining self-aligned and sidewall spacer techniques to fabricate the internal block layers under the both sides of channel end to form bMOS. The depleted region between source/drain and body is shielded and so the short channel effects and the controllability of gate to channel are improved. The internal block layers not only maintain the character of internal block layers but also ameliorate the drawback of bVMOS. The ISE TCAD simulation results show the short channel effect is suppressed and the thermal instability is improved by the internal block layers effectively in each device. Furthermore, we employ the epitaxial silicon-germanium thin film process (bSGMOS) to form silicon-germanium thin film at source/drain region to improve the device current drive by the strain thereby enhancing the device performance.

Storage is a central part of computing. Driven by exponentially increasing content generation rate and a widening performance gap between memory and secondary storage, researchers are in the perennial quest to push for further innovation. This has resulted in novel ways to “squeeze” more capacity and performance out of current and emerging storage technology. Adding intelligence and leveraging new types of storage devices has opened the door to a whole new class of optimizations to save cost, improve performance, and reduce energy consumption. In this dissertation, we first develop, analyze, and evaluate three storage exten- sions. Our first extension tracks application access patterns and writes data in the way individual applications most commonly access it to benefit from the sequential throughput of disks. Our second extension uses a lower power flash device as a cache to save energy and turn off the disk during idle periods. Our third extension is designed to leverage the characteristics of both disks and solid state devices by placing data in the most appropriate device to improve performance and save power. In developing these systems, we learned that extending the storage stack is a complex process. Implementing new ideas incurs a prolonged and cumbersome de- velopment process and requires developers to have advanced knowledge of the entire system to ensure that extensions accomplish their goal without compromising data recoverability. Futhermore, storage administrators are often reluctant to deploy specific storage extensions without understanding how they interact with other ex- tensions and if the extension ultimately achieves the intended goal. We address these challenges by using a combination of approaches. First, we simplify the stor- age extension development process with system-level infrastructure that implements core functionality commonly needed for storage extension development. Second, we develop a formal theory to assist administrators deploy storage extensions while guaranteeing that the given high level goals are satisfied. There are, however, some cases for which our theory is inconclusive. For such scenarios we present an experi- mental methodology that allows administrators to pick an extension that performs best for a given workload. Our evaluation demostrates the benefits of both the infrastructure and the formal theory.

This thesis presents the I/O layer of Linux kernel and shows various tools for tuning and optimization of its performance. Many tools are presented and their usage and outputs are studied. The thesis then focuses on the means of combining such tools to create more applicable methodology of system analysis and monitoring. The practical part consists of applying SystemTap scripts for blktrace subsystem and creating a fragmentation monitoring tool with graphical output.