The Stress and Morphology Evolution of CZO Films Under Different Growth Temperature

Zn_1−xCo_xO (x = 0.05, CZO) thin films are deposited on Si(111) and glass substrates at different substrate temperatures from 350 to 500 °C. All the CZO films on glass substrates exhibit compressive stress, but for the films deposited on Si substrates, the change from compressive to tensile one is observed. The increase of Ts is favorable for the reduction of stress in the films. Roughness exponent α, RMS roughness w and autocorrelation length ξ are calculated. At lower temperature, for both substrates, α is less than 0.65, indicating lower temperature could not provide sufficient energy for the free migration and diffusion of the deposited atoms. The ratio of w/ξ increases with the increase of Ts from 350 to 450 °C, suggesting that the upward growth of the CZO film depends much more on growth temperature than the lateral one. When the temperature increases further, w/ξ decreases, but the morphology of CZO films shows the same evolution feature in spite of the type of substrate, indicating that Ts plays a dominate role rather than substrates in the ratio of w/ξ CZO films.