Magnetic Interactions between Donor Clusters in Phosphorus Doped Silicon

抄録

We present a new model to interpret the asymmetry of the Electron Spin Resonance spectrum observed at low temperature and high microwave frequency, in phosphorus doped silicon in the concentration region 2×10¹⁷cm⁻³ to 10¹⁸cm⁻³. This model is based upon the distinction between isolated and strongly coupled donors. The exchange energy that determines this separation is one order of magnitude larger than the hyperfine interaction between the electron and the nucleus of the donor. Strongly coupled donors constitute clusters: Interactions between these clusters and isolated donors are of the same order of magnitude or smaller than the hyperfine coupling, and cause the spectrum to be asymmetric when the electronic polarization is large. We are able to perform a complete Monte Carlo calculation of the donors distribution and to determine the resulting spectrum for a concentration 2×10¹⁷cm⁻³: The result is in good agreement with the experimental curve.