Dependence of structural and optical properties of Zn1–xCdxO films on the Cd composition

Zn1–xCdxO alloy semiconductors have great latent applications in short wavelength optoelectronic devices. By the dc reactive magnetron sputtering technique, ternary single-phased Zn1–xCdxO (0 ≤ x ≤ 0.53) alloy crystalline films were prepared on glass and sapphire substrates. For x = 0, 0.20, 0.36, 0.53, the band-gaps of the Zn1–xCdxO alloy films were estimated as 3.28, 3.21, 3.11 and 2.65 eV, respectively. Photoluminescence spectrum shows that the near-band-edge energy of the Zn0.8Cd0.2O film has a red-shift of 0.14 eV from that of pure ZnO reported previously. The green-yellow emission in the photoluminescence spectrum is assumed to mainly related to electron transitions from the single ionized oxygen vacancies (Vo+) to Zn, Cd vacancies (VZn–, VC–d), or oxygen interstice (Oi–). (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)