Lattice defects having strong paramagnetic resonances are introduced into $p$-type silicon that has been bombarded with electrons. We have studied the paramagnetic properties and growth of the dominant defect so introduced (the $K$ center) as functions of electron flux and bombardment energy under conditions of different resistivities, impurity dopants, and illumination. The defect has a spin of ½ and has $g$ values of 2.0000, 2.0066, and 2.0056 for the principal magnetic axes, which lie along the $〈221〉$, $〈1\overline{1}0〉$, and $〈11\overline{4}〉$, crystallographic directions, respectively. No hyperfine interactions are observed. The introduction rates for the $K$ center are 0.006, 0.025, 0.073, and 0.11 ${\mathrm{cm}}^{-1\mathrm{}}$ at bombardment energies of 0.7, 1, 3, and 6.6 MeV, respectively. The $K$ center is independent of the $p$-type dopant. It is not a primary defect, but requires oxygen. At high integrated electron fluxes the EPR-measured $K$-center concentration decreases; however, illumination and annealing experiments have established that the defects are still present but have a different charge state because they have trapped an electron. The EPR measurements have been paralleled by Hall-effect measurements. We have associated the $K$ center with a previously reported 0.3-eV defect level on the grounds that both require oxygen, that both have about the same introduction rates and bombardment energy dependence, and that the value of the Fermi level at which the $K$-center EPR absorption decreases sharply is about 0.3 eV.

• Received 20 April 1966

DOI:https://doi.org/10.1103/PhysRev.149.687