The relaxation rate of the magnetic moment of a shallow acceptor center asa function of impurity concentration in silicon

A study is made into the temperature dependence of residual polarization of negative muons in crystalline silicon with the concentration of impurity o f the n- and p-types ranging from 8.7 x 10(13) to 4.1 x 10(18) cm(-3). The measurements are performed in a magnetic field of 1000 G transverse to the muon spin, in the temperature range from 4.2 to 300 K. The form of the temp erature dependence of the relaxation rate nu of the magnetic moment of the Al-mu(0) acceptor in silicon is determined. For a nondegenerate semiconduct or, the relaxation rate depends on temperature as nu proportional to T (q) (q approximate to 3). A variation in the behavior of the temperature depend ence and a multiple increase in the relaxation rate are observed in the ran ge of impurity concentration in excess of 10(18) cm(-3). The importance of phonon scattering and spin-exchange scattering of free charge carriers by a n acceptor from the standpoint of relaxation of the acceptor magnetic momen t is discussed. The constant of hyperfine interaction in an acceptor center formed by an atom of aluminum in silicon is estimated for the first time: parallel toA(hf) (Al)/2 pi parallel to similar to 2.5 x 10(6) s(-1). (C) 20 01 MAIK "Nauka/Interperiodica".