Direct observation of the crystal structure changes in the MgxZn1 − xO alloy system

• MgxZn1 − xO thin films coexisting with cubic and hexagonal structures were deposited.
• Crystal structure changes of the thin films were directly observed at 500 °C.
• The process of microstructure changes could be caused by the evaporation of Zn atoms.

We directly observed the crystal structure changes of the MgxZn1 − xO alloy thin film deposited on Si (111) substrates. Through the in situ heating transmission electron microscopy study, it was determined that the crystal structure changes did not occur up to at 400 °C, whereas the disappearance of the hexagonal structure was observed at 500 °C in the layer of nanosized grains. Additionally, the decreased intensity of the Zn L-edge was analyzed in the comparison of the core loss electron energy loss spectroscopy spectra of the Zn L-edge and the Mg K-edge obtained at room temperature and 500 °C. Based on these experimental results, the process of crystal structure changes could be explained by the evaporation of Zn atoms in the MgxZn1 − xO alloy system. This phenomenon is prominent in the improvement of the microstructure of the MgxZn1 − xO alloy thin film by controlling the thermal annealing temperature.