Comparative study of accurate experimentally determined and calculated band gap of amorphous ZnO layers

Abstract

In this work, amorphous ZnO thin films were prepared by sol–gel technique using zinc acetate dehydrate and diethanol amine. The synthesized films have been deposited on glass substrates and heated at 150°C. X-ray diffractions have been carried out to analyze the fabricated films structure. The optical transmission in the UV–visible spectral range is found to be important characteristic to assess the quality of the deposited layers. The X ray diffraction results indicated that the zinc oxide structure is amorphous, after instant preparation of the precursor sols. The as prepared films exhibited UV transmittance at around 85% in visible range with the estimated direct band gap energy varying from 3.6 to 3.2 eV when the layer thickness increases from 400nm to 1μm.The obtained results are assessed by Comparative study of accurate theoretical bandgap calculations of ZnO thin films and experimentally determined band gap of amorphous ZnO layers. Theoretical calculations of ZnO band gap was performed by the full potential linearized augmented plane wave (FP-LAPW) method with the modified Becke-Johnson (mBJ) potential and via generalized gradient approximation (GGA). After careful analysis of the results presented in this work we have deduced that the mBJ potential is found to be more efficient in the calculations of band gap.