DFT investigation of structural, electronic and optical properties of pure and Er-doped ZnO: Modified Becke-Johnson exchange potential

The structural, electronic and optical properties of pure ZnO and Er-doped ZnO are investigated by density functional theory (DFT) with generalized gradient approximation plus modified Becke-Johnson exchange potential (GGA + mBJ). The obtained results of electronic and optical properties were improved. Good agreement with the experimental and theoretical studies is obtained for pure ZnO since the results of Er-doped ZnO in zinc blend structure are considered as new predictions. The energy gap value of Er-doped ZnO is found to increase with Erbium incorporation, affecting the absorption coefficients in all spectra regions. Red shift is also achieved under Er doping indicating the importance of its 4f donor occupied states. Similar behavior is observed in the literature for Er-doped ZnO in wurtzite structure.