Electron paramagnetic resonance of conduction-band electrons in silicon

The g value of conduction-band electrons in silicon was properly determined by using electron paramagnetic resonance. A linear empirical relationship was first found between the g values and the thermal ionization energies of several well-known group-V substitutional shallow donors in silicon. An extrapolation of the empirical relation to zero ionization energy predicted the g value of conduction-band (CB) electrons, ${\mathrm{g}}_{\mathrm{CB}}$=1.9995, which is slightly but definitely different from that of conduction electrons in the donor-impurity band of degenerate n-type silicon; although both g values have been tacitly accepted to be identical for nearly four decades. The prediction was directly verified by measuring the g value of CB electrons created either by thermal emission from shallow donors in phosphorus-doped silicon at T=125 K and by above-band-gap optical excitation in high-purity p-type silicon at T=3.5 K; the measured g value in both experiments was precisely ${\mathrm{g}}_{\mathrm{CB}}$=1.9995(1). The empirical relation is still not theoretically explained.