Band-edge transitions of a metallorganic chemical vapor deposited ZnO film on Si by thermoreflectance spectroscopy

Optical properties of the band-edge transitions of a ZnO film deposited on silicon substrate (ZnO/Si) were characterized using thermoreflectance (TR) measurements in the temperature range between 35 and 340 K. The TR spectrum of the zinc oxide film clearly showed many transition features present at energies near 3.4 eV at 35 K. The observed TR features correspond to the A, B, and C excitonic series in the wurtzite ZnO. Transition energies of the A, B, C excitonic series were analyzed by a detailed line-shape fit to the TR spectrum. The Rydberg constant and threshold energy for each A, B, and C excitonic series were determined. Temperature dependence of the transition energies of the A, B, and C series were analyzed. The parameters that describe the temperature variations of the excitonic transitions in the ZnO film were evaluated and discussed. (c) 2006 The Electrochemical Society.