| To model spectral ellipsometry (SE) data, we introduced a new model of the dielectric function for diamond and zincblende-type. semiconductors. Our model is the first to include discrete and band-to-band Coulomb enhanced (BBCE) effects, i.e., continuum exciton at the fundamental bandgap, the spin orbit split gap, and the higher lying E1, E 1+Delta1 doublet. Our analysis has yielded experimental evaluation of the 2D exciton binding energies at the E1, E1+Delta1 CP's, R1. We show that the features near the E1, E1+Delta1 CP's are actually due to the bound exciton, which can be several hundred meV below the these CP's. The extracted R1 values using our model are in good agreement with effective-mass k•p theory. |
