Optical properties of amorphous III–V compounds. I. Experiment

From reflectivity measurements ε 1 and ε 2 , the real and imaginary part of the dielectric constant, of the amorphous III‐V compounds InSb, InAs, InP, GaSb, GaAs, and GaP are determined in the fundamental absorption region up to 12 eV. Compared with the corresponding curves of the crystals, the spectra of the disordered materials are smeared out and shifted to lower energy. This shift leads to an increase of ε 1 (0). In the energy region of the E 2 ‐peaks a selective decrease of ε 2 is observed. The results for ε 2 are briefly discussed in terms of structural properties, and a modified Penn model is applied to the spectral dependence of ε 2 .