Microscopic structure and electrical transport property of sputter-deposited amorphous indium-gallium-zinc oxide semiconductor films

26th Symposium on Plasma Sciences for Materials

物理学;材料科学

Yabuta, H.^1 ; Kaji, N.^1 ; Shimada, M.^1 ; Aiba, T.^1 ; Takada, K.^1 ; Omura, H.^1 ; Mukaide, T.^1 ; Hirosawa, I.^2 ; Koganezawa, T.^2 ; Kumomi, H.^1

Corporate RandD Headquarters, Canon Inc., 3-30-2 Shimomaruko, Ohta-ku, Tokyo 146-8501, Japan^1

SPring-8, Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Mikazuki-cho, Hyogo 679-5198, Japan^2

关键词: Amorphous indium gallium zinc oxides (a igzo);    Amorphous-indium gallium zinc oxides;    Electrical and optical properties;    Electrical transport properties;    Optical band gap energy;    Temperature dependence;    Two-dimensional conduction;    X ray small angle scatterings;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/518/1/012001/pdf
DOI  :  10.1088/1742-6596/518/1/012001

学科分类：材料科学（综合）

来源: IOP

【 摘 要 】

We report on microscopic structures and electrical and optical properties of sputter-deposited amorphous indium-gallium-zinc oxide (a-IGZO) films. From electron microscopy observations and an x-ray small angle scattering analysis, it has been confirmed that the sputtered a-IGZO films consist of a columnar structure. However, krypton gas adsorption measurement revealed that boundaries of the columnar grains are not open-pores. The conductivity of the sputter-deposited a-IGZO films shows a change as large as seven orders of magnitude depending on post-annealing atmosphere; it is increased by N2-annealing and decreased by O2-annealing reversibly, at a temperature as low as 300°C. This large variation in conductivity is attributed to thermionic emission of carrier electrons through potential barriers at the grain boundaries, because temperature dependences of the carrier density and the Hall mobility exhibit thermal activation behaviours. The optical band-gap energy of the a-IGZO films changes between before and after annealing, but is independent of the annealing atmosphere, in contrast to the noticeable dependence of conductivity described above. For exploring other possibilities of a-IGZO, we formed multilayer films with an artificial periodic lattice structure consisting of amorphous InO, GaO, and ZnO layers, as an imitation of the layer-structured InGaZnO4 homologous phase. The hall mobility of the multilayer films was almost constant for thicknesses of the constituent layer between 1 and 6 A, suggesting rather small contribution of lateral two-dimensional conduction It increased with increasing the thickness in the range from 6 to 15 A, perhaps owing to an enhancement of two-dimensional conduction in InO layers.