Abstract
The optical absorption spectra of V2O5—B2O3—ZnO semiconducting glasses, prepared by rf sputtering, indicate that the interband transitions are direct forbidden; for glasses with 50% to 90% V2O5 the optical band gap ranges from 2.51 to 2.31 eV at 100 K. Below the absorption edge the spectra exhibit an Urbach tail. The shapes of the electro‐ and thermomodulation spectra agree qualitatively with theoretical predictions based on the Franz‐Keldysh effect. From a quantitative analysis of the electromodulation spectra in the Urbach tail region a reduced effective mass of 10 mo is derived and band gap values which are 0.2 eV larger than the values obtained from the absorption spectra.