ULTRAHIGH-RESOLUTION PHOTOLUMINESCENCE STUDIES OF EXCITONS BOUND TO BORON IN SILICON IN MAGNETIC-FIELDS

The Zeeman effect on bound excitons in Si doped with boron has been st udied in magnetic fields of up to 12 T, using Fourier-transform photol uminescence spectroscopy with a resolution of 3 mueV. Up to 20 narrow spectral components of the no-phonon boron-bound-exciton line have bee n resolved in each of the three [001], [111], and [110] samples orient ations. In addition to the linear paramagnetic splitting of spectral c omponents, a quadratic diamagnetic splitting was observed, and was att ributed to the difference in the diamagnetic shifts of the single-elec tron states associated with the different conduction-band minima. From the pattern of the bound-exciton splittings, the order of the valley- orbit energy levels has been determined to be GAMMA3, GAMMA5, GAMMA1, with level GAMMA3 being the lowest and GAMMA1 the highest. A perturbat ion Hamiltonian, constructed from symmetry considerations, and describ ing the valley-orbit splitting, interparticle correlations, and intera ctions with the magnetic field, was used for calculations of the boron -bound-exciton energy levels versus field. Phenomenological parameters , including interparticle-correlation constants, g factors, and diamag netic-shift constants were determined by simultaneously optimizing the fit between experimentally observed and calculated energy levels in s trong magnetic fields and under uniaxial stress.