[摘要]:A paramagnetic recombination center having an orthorhombic symmetry with g[110] = 2.0095(2), g[001] = 2.0038(2), and g[(1) over bar 10] = 2.0029(2) is found at the interface between silicon and native oxide. The center is referred to P-m center and observed by a spin dependent recombination based electron paramagnetic resonance detection that has the sensitivity of similar to 10(11) spins/cm(2). The employment of an isotopically enriched Si-28 sample with the concentration of Si-29 nuclear spins reduced to 0.017% leads to narrowing of the resonance line. This narrowing is the key for the accurate determination of the angular dependence of the g-factor. (C) 2012 American Institute of Physics.[http://dx.doi.org/10.1063/1.3702785]