Investigating the Energy Band Gap of Fe2O3 Doped with Cr: Using the Photoacoustic Technique

Abstract

In the present paper, we report the observations made on the electronic properties of Fe2O3 thin films formed on a glass substrate, with different doping concentrations of chromium, using a photoacoustic spectroscopic (PAS) technique. Photoacoustic (PA) spectra of Fe2O3 thin films, with different doping concentrations of Cr, were recorded in the wavelength range of 300–700 nm at a modulation frequency of 22 Hz, using an indigenous PA spectrometer. The experimental data were interpreted in terms of the usual band theory for semiconductors. Absorption bands in Fe2O3 arise due to two types of electronic excitations, i.e., the d–d and p–d transitions. Energy band gap of the semi conducting sample (Fe2O3) was also determined using the absorption edge at the PA spectrum; it was found that the energy band gap increases with increasing doping concentration of Cr in Fe2O3.