A STATIC AND MAGIC-ANGLE SAMPLE-SPINNING NUCLEAR-MAGNETIC-RESONANCE SPECTROSCOPIC STUDY OF B-11 IN SI[B] - AN ANALYSIS OF SPIN SPIN AND SPIN-LATTICE RELAXATION BEHAVIOR IN THE METALLIC STATE

We have investigated the signal intensity, lineshape. spin-lattice and spin-spin (spin-echo decay) relaxation behavior of B-11 nuclei in a Si[B] extrinsic semiconductor in the metallic state, asa function of magnetic field strength and temperature. We find that essentially all boron spins are in a highly symmetric environment, characterized by a mean nuclear quadrupole coupling constant (e2qQ/h) of almost-equal-to 12 kHz. The spin-lattice relaxation is Korringa like, with a T1T almost-equal-to 550 s K. at both 5 and 300 K, indicating a mean Knight shift of almost-equal-to 70 ppm. The spin-spin relaxation time. T2E, is 25 ms at 8.45 T, independent of temperature, or magnetic field strength in the range 2.35 to 11.7 T, at 300 K. The T2E value is in good agreement with the predictions of a model of homonuclear dipolar interactions within metallic Si[B] clusters.