Electron spin resonance in doped nanocrystalline silicon films

We report studies of electron spin resonance (ESR) and its related defect states in doped nanocrystalline silicon films (nc-Si:H). The samples used, which were prepared by the plasma enhanced CVD method, contain two phases, i.e. nanocrystallites embedded in an amorphous matrix. For phosphorus doped nc-Si:H samples, the measured ESR g-values are 1.9990–1.9991, the line width ΔHpp 40–42 G, and the ESR density Nss is of order of 1017 cm−3. For boron doped nc-Si:H samples, the measured ESR g-values are 2.0076–2.0078, the ΔHpp is about 18 G, and the Nss is of order of 1016 cm−3. Considering the micro-structural and conducting characteristics of these kinds of films, we discuss and give explanations to the ESR sources, their ΔHpp and Nss as well. We intend to ascribe the ESR signal in phosphorus doped nc-Si:H to the unpaired electrons in the high density defect states located in the interfaces of nanocrystallites/amorphous matrix, and that in boron doped ones to the unpaired electrons in the valence band-tail states in the a-Si:H tissue of their amorphous matrix.