Abstract Ga-doped ZnO (GZO) films were grown by reactive co-sputtering of a Zn-GaAs target (3% area coverage of Zn by GaAs) at 375 °C with different partial pressures of oxygen. The resistivity of GZO films increases drastically from ≲10−3 Ω-cm to ~ 0.2 Ω-cm as the O2 in the sputtering atmosphere is changed from 5 % to 6 %. The films grown at 5% or lower O2 have the Ga/Zn ratio of ~ 0.1 and display low resistivity with carrier concentration ~ 1021 cm−3, while the films grown at 6% or higher O2 have lower Ga/Zn ratio of ~ 0.01 and display high resistivity with carrier concentration ~ 1019 cm−3. Extended X-ray absorption fine structure (EXAFS) measurements at Zn and Ga K-edges reveal substitutional incorporation of Ga in low resistivity films. X ray photoelectron spectroscopy (XPS) studies reveal a substantial decrease in oxygen vacancies together with increase in oxygen interstitials, in high resistivity GZO films. EXAFS measurements of the high resistivity films show a substantial increase in Ga-O and Ga-Zn bond distances and Ga-O coordination, indicating incorporation of oxygen interstitials in the vicinity of Ga. The comparison of measured and simulated X–ray absorption near edge spectra at O K-edge, together with XPS and EXAFS results, provides adequate experimental evidence of the presence of acceptor type (GaZn+Oi) defect complex, which cause carrier compensation in high resistivity films.

中文翻译：

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反应溅射氧化锌薄膜中 Ga 掺杂的 X 射线吸收光谱研究

摘要 Ga掺杂的 ZnO (GZO) 薄膜是通过 Zn-GaAs 靶材（GaAs 对 Zn 的面积覆盖率为 3%）在 375 °C 和不同的氧分压下反应共溅射生长的。随着溅射气氛中的 O2 从 5% 变为 6%，GZO 薄膜的电阻率从 ≲10−3 Ω-cm 急剧增加到 ~ 0.2 Ω-cm。在 5% 或更低 O2 条件下生长的薄膜具有 ~ 0.1 的 Ga/Zn 比并显示出低电阻率，载流子浓度约为 1021 cm-3，而在 6% 或更高 O2 条件下生长的薄膜具有 ~ 0.01 的较低 Ga/Zn 比并显示出高电阻率，载流子浓度约为 1019 cm-3。Zn 和 Ga K 边缘的扩展 X 射线吸收精细结构 (EXAFS) 测量揭示了 Ga 在低电阻率薄膜中的替代结合。X 射线光电子能谱 (XPS) 研究表明，在高电阻 GZO 薄膜中，氧空位显着减少，氧间隙增加。高电阻率薄膜的 EXAFS 测量显示 Ga-O 和 Ga-Zn 键距和 Ga-O 配位显着增加，表明在 Ga 附近掺入了氧间隙。 测量和模拟的 X 射线吸收在边缘附近的比较O K 边缘的光谱，连同 XPS 和 EXAFS 结果，提供了存在受体型 (GaZn+Oi) 缺陷复合物的充分实验证据，这会导致高电阻率薄膜中的载流子补偿。