Effect of Uniaxial Stress on Excitons Bound to Bismuth in GaP
Abstract
We have studied the effects of uniaxial compression on the zerophonon photoluminescence spectrum of excitons bound to bismuth impurities in GaP at liquidhelium temperatures. The quantitative stress dependence is consistent with the exciton being associated primarily with the <100> conductionband minima. The valleyorbit interaction is shown to lower the energy of the singlet, symmetric valley combination of the exciton, and the valleyorbit splitting is estimated to be 30 meV. The polarization of the emission with uniaxial stress applied to the sample, and the stress dependence of the emission lines, are only qualitatively consistent with the jj coupling model of the exciton. The deformation potentials D_{u} and D_{u}' for the J=1 state of the exciton are measured to be 0.17 and 0.8 eV, respectively, approximately an order of magnitude smaller than the corresponding freehole deformation potentials and about onehalf those of the J=2 state. The J=2 state is observed to be split by ~0.25 meV into a higher Γ_{3} and a lower Γ_{4} level. This splitting, as well as other inconsistencies with the simple model, is attributed in part to the dynamic JahnTeller effect.
 Publication:

Physical Review B
 Pub Date:
 March 1970
 DOI:
 10.1103/PhysRevB.1.2592
 Bibcode:
 1970PhRvB...1.2592O