Paramagnetism of Phosphorus Doped Silicon in the Non-Metallic Impurity Conduction

The temperature dependence of the paramagnetic susceptibility of phosphorus doped silicon with concentration of 3×10 16 cm -3 ∼4×10 18 cm -3 was investigated between 300°K and 1.5°K using 10 Gc electron spin resonance technique. Paramagnetism at 300°K originates from the conduction electrons. The contribution from the localized electrons becomes larger with lowering temperature. At liquid helium temperatures, a deviation from the 1/ T relation was observed beyond 1×10 18 cm -3 . The result suggests, together with the conductivity measurement of the same sample, the presence of antiparallel spin coupling between localized electrons, which has been assumed for the explanation of the static susceptibility measurements at low temperatures.