Structural properties of semipolar Al_<i>x</i>Ga_1−<i>x</i>N($1\bar {1}03$) films grown on ZnO substrates using room temperature epitaxial buffer layers

<jats:title>Abstract</jats:title><jats:p><jats:styled-content>$1\bar {1}03$<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="graphic/tex2gif-ueqn-2.gif" xlink:title="equation image" /></jats:styled-content>We have grown Al<jats:sub><jats:italic>x</jats:italic></jats:sub>Ga<jats:sub>1−<jats:italic>x</jats:italic></jats:sub>N films on semipolar ZnO (<jats:styled-content>$1\bar {1}03$<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="graphic/tex2gif-ueqn-3.gif" xlink:title="equation image" /></jats:styled-content>) substrates by pulsed laser deposition (PLD). The direct growth of Al<jats:sub>0.25</jats:sub>Ga<jats:sub>0.75</jats:sub>N on ZnO (<jats:styled-content>$1\bar {1}03$<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="graphic/tex2gif-ueqn-4.gif" xlink:title="equation image" /></jats:styled-content>) substrates at 850 °C results in the formation of <jats:italic>c</jats:italic>‐axis oriented materials with poor crystallinity due to serious interfacial reactions that occur between Al<jats:sub>0.25</jats:sub>Ga<jats:sub>0.75</jats:sub>N and ZnO. However, epitaxial Al<jats:sub><jats:italic>x</jats:italic></jats:sub>Ga<jats:sub>1−<jats:italic>x</jats:italic></jats:sub>N (<jats:styled-content>$1\bar {1}03$<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="graphic/tex2gif-ueqn-5.gif" xlink:title="equation image" /></jats:styled-content>) films can be grown on ZnO substrates by the incorporation of PLD room temperature (RT) epitaxial buffer layers. From X‐ray symmetric reciprocal space mapping studies, the [<jats:styled-content>$1\bar {1}03$<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="graphic/tex2gif-ueqn-6.gif" xlink:title="equation image" /></jats:styled-content>] directions of all Al<jats:sub><jats:italic>x</jats:italic></jats:sub>Ga<jats:sub>1−<jats:italic>x</jats:italic></jats:sub>N (<jats:styled-content>$1\bar {1}03$<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="graphic/tex2gif-ueqn-7.gif" xlink:title="equation image" /></jats:styled-content>) layers are slightly tilted toward the <jats:italic>c</jats:italic>‐axis from that of the ZnO substrate. We also found that the magnitude of the crystallographic tilt of Al<jats:sub><jats:italic>x</jats:italic></jats:sub>Ga<jats:sub>1−<jats:italic>x</jats:italic></jats:sub>N (<jats:styled-content>$1\bar {1}03$<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="graphic/tex2gif-ueqn-8.gif" xlink:title="equation image" /></jats:styled-content>) increases with AlN mole fraction <jats:italic>x</jats:italic>. This tendency can be explained by a reduction in the average misfit dislocation interval due to the increasing lattice mismatch between Al<jats:sub><jats:italic>x</jats:italic></jats:sub>Ga<jats:sub>1−<jats:italic>x</jats:italic></jats:sub>N and ZnO with AlN mole fraction <jats:italic>x</jats:italic>.</jats:p>