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

Abstract

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 3.01eV at room temperature are achieved by incorporating 13at% Cd content. Based on the X-ray diffraction analysis, the Zn1−xCdxO films with Cd content below 7.2at% exhibit unique non-polar 〈112¯0〉 orientation, while the films with Cd content above 7.2at% present 〈0001〉 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.