Nature of paramagnetic centers ina-Si anda-Si:H
- 1 August 1988
- journal article
- research article
- Published by American Physical Society (APS) in Physical Review B
- Vol. 38 (4), 2779-2786
- https://doi.org/10.1103/physrevb.38.2779
Abstract
A comparative ESR study has been undertaken of various kinds of a-Si and a-Si:H. Experiments on sputtered samples reveal that the local configuration of the usual dangling-bond (DB) centers (g≊2.0055) depends on the details of deposition. The g value may gradually be reduced to values as low as 2.0041 as a result of local-structure change. Regarding the g=2.004 signal originated from conduction-band-tail (CBT) states, it is shown that the effective correlation energy () is large and the temperature dependence of its spin density is due to the presence of donor levels—not due to a small- effect as has previously been concluded. Related to this, ample evidence is provided, indicating that the g=2.004 signal in P-doped a-Si:H and the g=2.005 DB line are in fact variants of the same kind of defect. Systematic analysis identifies the g=2.004 CBT states signal with -+ defect centers thus showing that a great deal of the CBT states are defect states rather than disorder-induced localized states. Regarding the g=2.013 signal in a-Si:H, evidence is provided showing that this cannot be associated with valence-band-tail states. Rather it concerns defects positioned at ≊0.6 eV above the valence-band mobility edge, whose nature is as yet to be determined. Their presence relates directly or indirectly to H incorporation.
Keywords
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