High-temperature stability of postgrowth-annealed Al-doped Mg _xZn_1-xO films without the phase separation effect

This study investigates the effects of thermal annealing on Al-doped Mg_xZn_1-xO (AMZO) films. AMZO films were deposited by a radio-frequency magnetron sputtering system using a 4 in. ZnO/MgO/Al ₂O₃ (76/19/5 wt. ) target. This study measures and reports the Hall results, x-ray diffraction (XRD), transmittance, and x-ray photoelectron spectroscopy (XPS) data. XRD results show that the ZnO (002) and MgO₂ (002) wurtzite peaks in addition to the (111)-cubic peak disappeared after 1000 °C annealing. This indicates the coexistence of two phases in the as-grown AMZO films rebuilt after higher thermal treatment. The absorption edges of these as-grown AMZO films shifted toward the short wavelength of 323 nm under 80 transmittance, implying that band gaps can be tuned by changing the Mg content of the AMZO layer. The XPS spectra of AMZO films were also used to analyze the composition of the as-grown and annealed AMZO films.