GROUND-STATE CHARACTERISTICS OF AN ACCEPTOR CENTER IN WIDE-GAP SEMICONDUCTORS WITH A WEAK SPIN-ORBIT-COUPLING

Spin-orbit splitting, strain-potential constants, and the g factor of the acceptor-center ground state described by a superposition of a Cou lomb and a central-cell potential have been calculated for wide-band-g ap semiconductors, such as GaN. Analytical expressions for these param eters, which depend only on the light- to heavy-hole mass ratio, have been obtained within the zero-range potential model. It is shown tb.at the differences between these parameters for the limiting cases of pu rely Coulomb and zero-range potentials do not exceed 7%, thus permitti ng one to use for estimates simple analytical expressions. Calculation of the acceptor center ground state made for the hexagonal modificati on of GaN suggests a strong anisotropy of the g factor, whereas measur ements yield a practically isotropic value of g close to that of a fre e electron. This contradiction is removed if a spontaneous strain due to the Jahn-Teller effect appears perpendicular to the C-6 axis of the crystal near the acceptor center. (C) 1998 American Institute of Phys ics.