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 phosphorus-doped silicon grown in a hydrogen atmosphere as a result of irradiation by thermal neutrons were investigated in magnetic fields up to 12 T and under uniaxial stress. The C-3v symmetry of these defects was determined unambiguously from the dependences of the Zeeman splitting and the intensities of spectral components on magnetic-field orientation. The ground state of the bound exciton is split into a doublet with 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 magnetic field. Using group theoretical methods we constructed a Hamiltonian for excitons bound to the B-71(1) isoelectronic center, which takes into account electron-hole coupling and interaction with external perturbations. 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.