Anomalous band bowing in pulsed laser deposited MgxZn1−xO films

• Single phase Mg doped ZnO films were pulsed laser deposited.
• Lattice relaxation in the films was ascribed to oxygen vacancies and interstitials.
• The band gap increases with the increasing Mg concentration.
• The presence of O vacancies and interstitials causes anomalous band bowing.

Random variation of band bowing in pulsed laser deposited Mg doped (x=0.090, 0.147, 0.211, 0.268) ZnO thin films was observed. The X-ray diffraction and ultraviolet–visible spectroscopy data reveal lattice relaxation and increase in band gap as well as disorderness in the samples. The X-ray photoelectron spectroscopy data confirm the presence of magnesium and oxygen interstitials (Mgi and Oi) as well as oxygen vacancies (VO). The randomness of band bowing is attributed to the presence of these defects.