Degree Type


Date of Award


Degree Name

Doctor of Philosophy


Physics and Astronomy


Proton magnetic resonance and electron paramagnetic resonance measurement results are presented for several reactively sputtered amorphous silicon-hydrogen alloys and for a few amorphous silicon-hydrogen-deuterium alloys. Proton NMR absorption measurements made on a series of samples with controlled and varied amounts of hydrogen have been interpreted as evidence for significant inhomogeneity in the local hydrogen density: there is a phase of the material, in which the hydrogen bonded to Si is randomly distributed with average local density 3.39 x 10('21) cm('-3); there is a hydrogen cluster defect with average local hydrogen density 4.34 x 10('22) cm('-3); in the lower hydrogen samples there is a third phase of the material which has no H;Proton NMR spin-lattice relaxation measurements as a function of both temperature and H concentration have been interpreted, consistent with the above conclusions. The mechanism of spin-lattice relaxation in both cases involves spin diffusion to relaxation centers. In the low H concentration samples the relaxation centers are dangling bond electrons, while the centers in the high H samples appear to be three-center Si-H-Si bonds;EPR measurements on the dangling bond electrons are consistent with all of the above conclusions. Furthermore, a new very broad ((TURN).1 Tesla) resonance has been detected in all of the samples. It is tentatively interpreted in support of the existence of three-center bonds;The implications these results may have for the electronic device properties of this material are discussed.



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Mark E. Lowry



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227 pages