Electron spin resonance (ESR) measurements have been made on a phosphorus-doped silicon specimen (n = 1.38 × 1019/cc) in the liquid helium temperature range. A single line with a g factor of approximately 2 was observed for resonant magnetic fields of 540, 3230, and 12 590 G at 1517, 9010, and 35 200 MHz respectively. The experimentally determined magnetization is compared with the magnetizations expected from the following sources: (a) un-ionized charge carriers or local magnetic moments obeying a Curie law, (b) mobile carriers experiencing an exchange interaction with local magnetic moments, and (c) mobile charge carriers showing only Pauli paramagnetism. The magnetization derived from the ESR data exhibits a linear dependence with magnetic field and no temperature dependence. This is consistent with the Pauli paramagnetism expected for mobile charge carriers in the absence of any interaction with local moments.
