Temperature dependence of the direct bandgap and transport properties of CdO

Temperature-dependent optical absorption, Hall effect, and infrared reflectance measurements have been performed on as-grown and post-growth annealed CdO films grown by metal organic vapor phase epitaxy on sapphire substrates. The evolution of the absorption edge and conduction electron plasmon energy with temperature has been modeled, including the effects arising from the Burstein-Moss shift and bandgap renormalization. The zero-temperature fundamental direct bandgap and band edge effective mass have been determined to be 2.31 ± 0.02 eV and 0.27 ± 0.01 m 0, respectively. The associated Varshni parameters for the temperature dependence of the bandgap are found to be α = 8 × 10-4 eV / K and β = 260 K. © 2013 American Institute of Physics.