Berlin 2005 – wissenschaftliches Programm

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DS: Dünne Schichten

DS 2: Elektrische und optische Schichteigenschaften

DS 2.1: Vortrag

Freitag, 4. März 2005, 10:45–11:00, TU HS107

ESR investigation of a donor-like state in epitaxial Si layers — •Kai Petter, Björn Rau, Klaus Lips und Walther Fuhs — Hahn-Meitner-Institut, Abteilung Silizium-Phovoltaik, Kekuléstr. 5, 12489 Berlin

Epitaxial silicon layers (∼ 1 µm thick) grown by electron cyclotron resonance chemical vapour deposition (ECR-CVD) are investigated by Electron Spin Resonance (ESR). The ESR spectra are dominated by two resonances at g=2.006 and 1.999. Here, we investigate the resonance at g=1.999, a localised state near the conduction-band. The spin density of this resonance at 5K is approximately equal to the charge carrier concentration at room temperature. When the samples are excited by above-bandgap light, the ESR signal increases and saturates for high light intensities. The increase and the saturation light intensity are, however, different for different samples. These results can be explained in a model of an n-type semiconductor with different concentrations of compensating acceptors where the ESR resonance is caused by occupied donors. Based on this model we show to which degree our measurements can be used to determine the concentrations of donors and acceptors and therefore the level of compensation in our material. The limitations that arise from the fact that the concentrations of the occupied acceptors are not accessible by our measurements will also be discussed.