On the Experimental Determination of Many‐Particle Effects at Interband Transitions

The energy‐derivative spectra of the real and imaginary part of the dielectric function ε(ω) = ε1 + iε2 in the range of critical interband transitions can be used to determine a parameter which describes the influence of many‐particle effects. Afterwards the computation of the one‐electron spectra becomes possible from experimental spectra, which are modified by many‐particle interactions. The application of this procedure to ellipsometrically determined spectra of GaP and GaAs for the E1 transition results in the predominant influence of the continuum—exciton effect in accordance with theoretical predictions of Hanke and Sham.