Investigation on the Effect of Charge Carriers in Chemical Shift Anisotropy of Si Single Crystal

The Chemical Shift Anisotropy (CSA) of single crystalline silicon (Si) was investigated using 29 Si static NMR for commercially procured p-type and n -type silicon. The observed CSA has been distributed between -80 ppm to -90 ppm for n- type and p -type Si. The NMR parameters such as Isotropic Chemical Shift (5 iso ), Chemical Shift Anisotropy tensor (ΔS) and the asymmetry parameter ( 77 ) of the CSA were extracted by using DMFIT with the CSA-static model. The Δ S and rj are found to be - 1.73 ppm and 0.3 ppm respectively for the n -type and the asymmetry parameter of the CSA was found one order different from p -type material. The changes observed in CSA pattern and spin-lattice relaxation ( T 1 ) time are ascribed to strength (mobility) of the shallow donor level and shallow acceptor level effects in the Fermi contact term.