Growth and Characterization of Nonpolar (10(1)over-bar0) Zn1-xMgxO (0 ≤ x ≤ 0.113) Epitaxial Films: A Comparison of γ-LiAlO2 (100) and Sapphire (10(1)over-bar0) Substrates

gamma-LiAlO2 (100) and sapphire (10 (1) over bar0) substrates have been employed to grow nonpolar (10 (1) over bar0) Zn1-xMgxO films using metalorganic chemical vapor deposition. Zn1-xMgxO films with various Mg contents (0 <= x <= 0.113) are obtained by adjusting the partial pressure of the Mg metalorganic precursor in gas phase. Mg atoms incorporate within the films by means of substituting Zn. No segregated phase such as MgO or metal Mg is observed throughout the Zn1-xMgxO films. Structural characterization of the films indicates that gamma-LiAlO2 (100) is a superior substrate to sapphire (10 (1) over bar0) for the growth of the nonpolar (10 (1) over bar0) Zn1-xMgxO films. The epitaxial (10 (1) over bar0) Zn1-xMgxO films are successfully grown on the gamma-LiAlO2 substrates with the epitaxial relationship of [10 (1) over bar0](ZMO) parallel to [100](LAO) and [1 (2) over bar 10](ZMO) parallel to [001](LAO). On the other hand, the Zn1-xMgxO films With both (10 (1) over bar0) and (10 (1) over bar3) orientations are obtained on sapphire substrates although Zn1-xMgxO (10 (1) over bar0) becomes dominant with increasing Mg content. In addition, room-temperature cathodoluminescence spectra of the epitaxial (10 (1) over bar0) Zn1-xMgxO films show an obvious blue-shift of the near-band-edge emission with increasing Mg content, demonstrating bandgap engineering in the epitaxial nonpolar (10 (1) over bar0) Zn1-xMgxO films on the gamma-LiAlO2 substrates.