Growth of non-polar a-plane Zn1−xCdxO films by pulsed laser deposition

• Non-polar Zn1−xCdxO films with different Cd content were grown on r-plane sapphire.
• The effects of oxygen pressure on Cd content in the Zn1−xCdxO films are discussed.
• Nnique 〈112¯0〉 orientation of Zn1−xCdxO can be obtained with Cd content below 7.2 at%.
• Alloying Cd modulates the band gap of ZnO from 3.30 to 3.01 eV at room temperature.

Non-polar Zn1−xCdxO thin films with different Cd content were grown on r-plane sapphire substrates by pulsed laser deposition. The effects of oxygen pressure on Cd content in the Zn1−xCdxO thin films are discussed. Single-phase Zn1−xCdxO thin films with a band gap of about 3.01 eV at room temperature are achieved by incorporating 13 at% Cd content. Based on the X-ray diffraction analysis, the Zn1−xCdxO films with Cd content below 7.2 at% exhibit unique non-polar 〈112¯0〉 orientation, while the films with Cd content above 7.2 at% present 〈0 0 0 1〉 and 〈112¯0〉 mixed orientations. The surface of Zn1−xCdxO film with pure a-plane orientation shows highly anisotropic morphology with stripes elongated along the c-axis.