Staebler-Wronski effect in tritiated amorphous silicon

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Hydrogenated amorphous silicon (a-Si:H)-represents one of the most important materials in the areas of photovoltaics and microelectronics. The introduction of tritium (an isotope of hydrogen) into amorphous materials has spurred fundamental studies on the nature of dangling bond defects and metastability. In 1995 the applicant initiated a systematic research of the properties of tritiated amorphous silicon. Preliminary studies have shown that tritium can be permanently bonded in amorphous silicon, thereby rendering this radioactive substance relatively safe. Phenomena associated with the decay of tritium offer a very powerful new tool in the study of amorphous semiconductors. In particular, Tritium decay within the a-Si:H network can be used to simulate and analyze the Staebler-Wronski (S-W) effect, which is responsible for the degradation of the opto-electronic properties of a-Si:H. Furthermore, the energy released during the decay can be harnessed and transformed into other, useful and harmless, forms of energy. The main objectives of this proposal are: to achieve a better understanding of the physical properties of amorphous semiconductors and of the effects of tritium in amorphous semiconductors. The research will be conducted at both theoretical and experimental levels. In addition, the energy "crunch" has brought the "nuclear solution" back to the forefront, and the Canadian nuclear plants, based on the CANDU reactor, represent a major and unique source of Tritium gas. This research will lead to the development and to the safe utilization of tritium in microelectronic devices, having the potential to benefit Canadian industry via exploration of practical applications of tritiated amorphous semiconductors, including self-powered light emitting devices and batteries. At least three M.Sc. students in the recently approved Master in Materials Science program will be involved in the research over the course of 5 years; several undergraduate students will also be involved in summer projects. The students will be provided training to: i) use Ab Initio Molecular Dynamics (AIMD) to simulate optoelectronic properties of semiconductors and other materials, ii) perform the experimental measurements required for the project.