PHOTOLUMINESCENCE OF EXCITONS BOUND TO THE ISOELECTRONIC HYDROGEN-RELATED DEFECTS B-71(1) (1.1377-EV) IN SILICON

Photoluminescence (PL) spectra of excitons bound to the isoelectronic defects B-71(1) (1.137 68 eV principal no-phonon line) created in phos phorus-doped silicon grown in a hydrogen atmosphere as a result of irr adiation by thermal neutrons were investigated in magnetic fields up t o 12 T and under uniaxial stress. The C-3v symmetry of these defects w as determined unambiguously from the dependences of the Zeeman splitti ng and the intensities of spectral components on magnetic-field orient ation. The ground state of the bound exciton is split into a doublet w ith approximately 30 mu eV energy separation. This splitting, which is not evident in the zero-field spectra because of the selection rules, results in the appearance of an additional spectral component in a ma gnetic field. Using group theoretical methods we constructed a Hamilto nian for excitons bound to the B-71(1) isoelectronic center, which tak es into account electron-hole coupling and interaction with external p erturbations. The phenomenological parameters of this Hamiltonian were determined from the optimal fit between theoretical and experimental dependences of the PL peak positions and their amplitudes on magnetic field and uniaxial stress. The proposed model of these bound excitons explains all of our experimental observations.