Electroabsorption of CdS and CdSe Single Crystals in the Exciton Region

Electroabsorption spectra in the exciton region were measured on very thin CdS and CdSe single crystals at 77 °K in the field range 1 × 10 3 to 2.4 × 10 4 V/cm for both polarizations of incident light with respect to the c ‐axis. The electroabsorption spectra exhibit much more details than electroreflection spectra know so far. The variation of peak positions and peak heights with electric field strength is different for different parts of the spectrum. Some of the peaks shift to lower and others o higher energies with increasing field strength. The spectra can be interpreted in terms of a second order Stark shift, field induced line broadening and Franz‐Keldysh type interband oscillations.