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 less than or equal to x less than or equal to 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 (V-o(+)) to Zn, Cd vacancies (V-Zn(-), V-Cd(-)) or oxygen interstice (O-i(-)). (C) 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.