FOURIER-TRANSFORM PHOTOLUMINESCENCE SPECTROSCOPY OF EXCITONS BOUND TOGROUP-III ACCEPTORS IN SILICON - ZEEMAN-EFFECT

Photoluminescence of excitons bound to Al, Ga, In, and Tl accepters in Si was studied at liquid-He temperatures in magnetic fields up to 14. 5 T with [001], [111], and [110] orientations with 0.0025-meV spectral resolution. All details of the Zeeman spectra for every field orienta tion, with up to 30 resolved spectral components, have been explained on the basis of a simple model of acceptor bound excitons with holes i n a singlet state J=0. The variation of the electron valley-orbit spli tting of the bound exciton energy levels in magnetic fields was used f or unambiguous identification of the zero-field valley-orbit state ord ering. An additional 0.02-meV splitting of the Gamma(5) bound exciton energy levels due to spin-orbit coupling was observed for In bound exc itons. The amplitude ratios in polarized Zeeman spectra agree with sel ection rules derived on the basis of the shell model. The ratios of th e selection rule constants determined from the zero-held spectra indic ate that hole scattering is responsible for no-phonon optical transiti ons in acceptor bound excitons. The electron spin and valley-orbit rel axation times were estimated to be longer than 3 ns and shorter than 7 6 ns on the basis of nonthermal population of the excited In and Tl bo und exciton energy levels and complete thermalization of the Al and Ga bound excitons.