Electron spin resonance studies on microcrystalline silicon

Müller, J.

Dissertation / PhD Thesis/Book

Electron spin resonance studies on microcrystalline silicon

Müller, J. (Corresponding author)FZJ*

1999
Forschungszentrum, Zentralbibliothek Jülich

Jülich : Forschungszentrum, Zentralbibliothek, Berichte des Forschungszentrums Jülich 3615, (1999) = Aachen, Techn. Hochsch., Diss., 1999

Please use a persistent id in citations: http://hdl.handle.net/2128/20228

Report No.: Juel-3615

Abstract: VHF-PECVD was used to prepare undoped as well as p- and n-type microcrystalline silicon with gas phase doping levels between 1 and 160 ppm and high crystalline volume fractions. The material was studied by steady state and transient electron spin resonance (ESR) at temperatures between 4 .2 and 300 K in the dark and under light illumination . The results are related to transport measurements . and the nature and energy position of the respective electronic states is clarified . Two resonances of defect states a.ppear at g-values of 2 .0043 and 2 .0052 over a wide doping ra.nge pointing to either a wide distribution in energy (0 .6 eV) or considera.ble potential fluctuations . A third resonance (b value around 1 .998) is due to donor. conduction band or conduction band tail states ; the respective occupancies depending on both temperature and doping level . In particula.r, for n-type samples the spin density of this latter resonance equals the donor density over two orders of magnitude . Hyperfine interaction with phosphorus nuclei is only observed at intermediate doping levels . A value of 12 A is found for the localization length of the donor wavefunction . The conduction process at temperatures below 20 K takes place via hopping between donor or conduction band tail states with a thermal activation energy of 3 .5 meV, while at higher temperatures carriers are excited into the conduction band . Illumination with White light (energy > 1 .75 eV) at low temperatures enhances different resonances depending on type and level of doping . In contrast to amorphous silicon, infrared light with energies smaller than 0 .67 eV also lea.ds to a light-induced signal enhancement. Transient light-induced ESR data are discussed in terms of a simple model, which includes both crvsta.lline and disordered/grain boundary regions separated from each other by potential barriers

Note: Record converted from VDB: 12.11.2012
Note: Aachen, Techn. Hochsch., Diss., 1999

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