The growth and characterization of multilayer structures by metalorganic chemical vapor deposition.

摘要

This dissertation provides insight into many aspects of compound semiconductor materials and device development, with emphasis on the application of metalorganic chemical vapor deposition (MOCVD) technology towards demonstration of a unique solar cell device. A broad spectrum of topics are presented, beginning with fundamental material purity studies as a vehicle to evaluate alternative arsenic sources for the growth of AlGaAs materials. This work led to the demonstration of a semiconductor laser using tertiarybutylarsine (tBAs) and demonstration of an on-demand hydride gas generator shown to produce GaAs materials of exceptional purity. Another major area of study focussed on the reproducible growth of distributed Bragg reflectors. Binary and ternary mirrors composed of single and multiple quarter-wave stacks were demonstrated, plus chirped periodicity designs as a method of extending the reflective band. The critical epitaxial requirements of these structures provided strong motivation for the development and implementation of an automated, in-situ growth rate monitoring probe. This tool, coined Laser Reflectometry (LR), provides automated MOCVD recipe correction leading to greatly improved reactor calibration and run-to-run reproducibility. This project provided a fundamental contribution towards such tools becoming common place on commercial MOCVD reactors. The final topic discusses the design, two-dimensional numerical simulation, fabrication and characterization of a unique GaAs-based solar cell concept called the Epitaxial Optical Reflector (EOR) cell. Solar cells with respectable performance were demonstrated, providing proof of concept. It is hoped that the broad approach represented in this body of work will highlight the symbionic relationship between semiconductor materials and device development.; The knowledge garnered during this array of projects has advanced MOCVD state-of-the-art, specifically in the areas of in-situ monitoring technology, the reproducible growth of precision distributed Bragg reflectors and alternative arsenic source implementation. The application of these advances towards the successful development of a unique solar cell device provides validation of the philosophy that device development begins with understanding and control of epitaxial materials requirements, while also highlighting that subsequent analysis of resulting devices is a critical feedback path for advancing the techniques of epitaxial materials preparation.