Nonhomogeneity of the Electrical Properties with Deposition Position in an ITO Thin Film Deposited under a Given R.F. Magnetron Sputtering Condition

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J. Korean Ceram. Soc. > Volume 38(11); 2001 > Article

Journal of the Korean Ceramic Society 2001;38(11): 973.

동일 증착 조건의 스퍼터링에 의해서 제작된 Indium Tin 산화물 박막의 증착위치에 따른 전기적 특성의 불균질성

유동주, 최시경

한국과학기술원 재료공학과

Nonhomogeneity of the Electrical Properties with Deposition Position in an ITO Thin Film Deposited under a Given R.F. Magnetron Sputtering Condition

ABSTRACT

Tin-doped indium oxide (ITO) thin films were deposited using r.f. magnetron reactive sputtering and the electrical properties, such as the resistivity, carrier concentration and mobility, were investigated as a function of the sample position under a given magnetron sputtering condition. The nonhomogeneity of the electrical properties with the sample position was observed under a given magnetron sputtering condition. The resistivity of ITO thin film on the substrate which corresponded to the center of the target had a minimum value, 2∼4$times$10$^$-4/$Omega$$.$cm, and it increased symmetrically when the substrate deviated from the center. The density measurement result also showed that ITO thin film deposited at the center has a maximum density of 7.0g/cm$^3$, which was a relative density of about 97%, and the density decreased symmetrically as the substrate deviated from the center. The nonhomogeneity of electrical properties with the deposition position could be explained with the incidence angle of the source beam alpha, which is related with an atomic self-shadowing effect. It was confirmed experimentally that the density in film affect both the carrier mobility and the conductivity. In the case where the density of ITO thin film is 7.0g/cm$^3$, the magnitude of the mean free path was identical with that of the grain size(the diameter of column). However, in the other cases, the mean free path was smaller than the grain size. These results showed that the scattering of the free electrons at the grain boundary is the major factor for the electrical conduction in ITO thin films having a high density, and there exists other scattering sources such as vacancies, holes, or pores in ITO thin films having a low density.ing a low density.

Key words: ITO thin film, Deposition, Nonhomogeneity of electrical properties, Film density