Dangling bonds in amorphous silicon investigated by multifrequency EPR

Paramagnetic coordination defects in undoped hydrogenated amorphous silicon (a-Si:H) are studied using multifrequency pulsed electron-paramagnetic resonance (EPR) spectroscopy at S-, X-, Q- and W-band microwave frequencies (3.6, 9.7, 34, and 94 GHz, respectively). The improved spectral information extractable from a multifrequency fitting procedure allows us to conclude that the g tensor exhibits a rhombic splitting instead of axial symmetry. Our methods allow for precise and accurate determination of the g tensor principal values gx = 2.0079(2), gy = 2.0061(2) and gz = 2.0034(2) and their distribution parameters (g strain).

► We investigated defects in a-Si:H by multifrequency EPR.
► Application of low- and high-field EPR allows obtaining information on g-tensor and hyperfine interactions.
► We found that the g-tensor of defects in a-Si:H exhibits rhombic symmetry.