Man, N.; Bikowski, A.; Ellmer, K.:
Microstructure evolution of Al-doped zinc oxide and Sn-doped indium oxide deposited by radio-frequency magnetron sputtering: A comparison. Journal of Applied Physics 117 (2015), p. 155301/1-9
10.1063/1.4916725
Abstract:
The microstructure and morphology evolution of Al-doped zinc oxide (AZO) and Sn-doped indium
oxide (ITO) thin films on borosilicate glass substrates deposited by radio-frequency magnetron
sputtering at room temperature (RT) and 300 °C were investigated by X-ray diffraction and atomic
force microscopy (AFM). One-dimensional power spectral density (1DPSD) functions derived
from the AFM profiles, which can be used to distinguish different growth mechanisms, were used
to compare the microstructure scaling behavior of the thin films. The rms roughness Rq evolves
with film thickness df as a power law, R = c*df^b, and different growth exponents b were found for
AZO and ITO films. For AZO films, b of 1.47 and 0.56 are obtained for RT and 300 °C depositions,
respectively, which are caused by the high compressive stress in the film at RT and relaxation of
the stress at 300 °C. While for ITO films, b = 0.14 and b = 0.64 for RT, and b = 0.89 and
b = 0.3 for 300 °C deposition are obtained, respectively, which is related to the strong competition
between the surface diffusion and shadowing effect and/or grain growth. Electrical properties of
both materials as a function of film thickness were also compared. By the modified Fuchs-
Sondheimer model fitting of the electrical transport in both materials, different nucleation states are
pointed out for both types of films.