Doping control is the most important technology for any semiconductor system. In spite of significant progress in the doping of SiC, advancements are needed in the growth techniques and dopant incorporation. During processes such as Chemical Vapor Deposition (CVD), hydrogen is known to be trapped at defects or impurities and to alter the electrical properties of the material. This effect is known as ?hydrogen passivation?. In addition to the observed hydrogen passivation of shallow impurities in SiC crystals, it is important to know whether, and how, hydrogen present in the epi ? reactor can passivate doping impurities during growth of the material. Variations in hydrogen incorporation can affect the net doping density and make process control difficult. This makes it essential for technologists to understand the process of hydrogen passivation and its effects on the doping concentration in the crystal. To understand this phenomenon, a process has been developed to intentionally hydrogenate SiC crystals by striking a hydrogen plasma using the Reactive Ion Etching (RIE) System in the Emerging Materials Research Laboratory at MSU. Photoluminescence (PL) and Capacitance ? Voltage (CV) were used to determine the effect of hydrogen incorporation on dopants in the SiC crystal lattice. Crystal annealing was performed at 1000 oC using the Thermco Oxidation Furnace to drive hydrogen out of the lattice (a process referred to as ?de-hydrogenation?). PL and CV measurements were taken to look for changes in the hydrogen concentration as well as free carrier concentration, respectively. Experiments conducted during this thesis research were successful in incorporating hydrogen and then driving it out of the lattice. CV profiling did not indicate a considerable change in free carrier concentration, probably because of the shallow diffusion depth of hydrogen in the SiC lattice. More reliable characterization techniques such as Secondary Ion Mass Spectrometry (SIMS) are required to get a clear picture of the doping densities of all chemical species present in the lattice at the end of each processing stage. However, resources did not permit this to be conducted during this preliminary work. As a result of this research, a process for hydrogenating and de-hydrogenating the SiC lattice has been developed to permit more extensive future studies.
| Identifer | oai:union.ndltd.org:MSSTATE/oai:scholarsjunction.msstate.edu:td-1233 |
| Date | 12 May 2001 |
| Creators | Rao, Yeswanth Lakshman |
| Publisher | Scholars Junction |
| Source Sets | Mississippi State University |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Theses and Dissertations |
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