Effect of Doping on the Electron Spin Resonance in Phosphorus Doped Silicon. IV. Experimental Study at Liquid Helium Temperature

Abstract

Electron spin resonance experiments on phosphorus doped silicon were carried out at liquid helium temperature in order to know the origin of the absorption line observed at the center of the hyperfine structure. The shape of the central line was Lorentzian. The line width showed minimum against the phosphorus concentration, while the g-value was constant. Resonance behaviors of the central line were different in following respects from those of hyperfine lines; (1) g-value, (2) concentration dependence of line width, (3) line shape, and (4) saturation behavior. These results were discussed in connection with the electrical conduction and temperature dependence of resonance parameters. A tentative model was proposed that the central line was assigned to the free electron in impurity clusters formed through the local enhancement of impurity concentration.