Magnetic moment relaxation of a shallow acceptor center in heavily doped silicon

Results of studying the temperature dependence of the residual polarization of negative muons in crystalline silicon with germanium (9 x 10(19) cm(-3) ) and boron (4.1 x 10(18), 1.34 x 10(19), and 4.9 x 10(19) cm(-3)) impuriti es are presented. It is found that, similarly to n- and p-type silicon samp les with impurity concentrations up to similar to 10(17) cm(-3), the relaxa tion rate nu of the magnetic moment of a Al-mu acceptor in silicon with a h igh impurity concentration of germanium (9 x 10(19) cm(-3)) depends on temp erature as nu similar to T (q), q approximate to 3 at T = (5-30) K. An incr ease in the absolute value of the relaxation rate and a weakening of its te mperature dependence are observed in samples of degenerate silicon in the g iven temperature range. Based on the experimental data obtained, the conclu sion is made that the spin-exchange scattering of free charge carriers make s a significant contribution to the magnetic moment relaxation of a shallow acceptor center in degenerate silicon at T less than or similar to 30 K. E stimates are obtained for the effective cross section of the spin-exchange scattering of holes (sigma (h)) and electrons (sigma (e)) from an Al accept or center in Si: sigma (h) similar to 10(-13) cm(2) and sigma (e) similar t o 8 x 10(-15) cm(2) at the acceptor (donor) impurity concentration n(a)(n(d )) similar to 4 x 10(18) cm(-3). (C) 2001 MAIK "Nauka/Interperiodica".