In this study, dual phase ZnO–NiO p–n composite thin films were grown through radio-frequency cosputtering of ceramic ZnO and NiO targets. During the cosputtering thin-film growth, the sputtering power of NiO was varied from 50 W to 110 W, while the ZnO sputtering power was fixed at 120 W herein. The composition analysis revealed that the Ni content in the composite films varied with the NiO sputtering power and is from 3.6 to 23.7 at%. The structural analysis revealed that the NiO sputtering power substantially changed the relative phase content in the composite film; moreover, the surface morphology and grain size of the composite film are highly dependent on the NiO sputtering power. The surface grain size increased and its morphology changed to a large pyramidal stereo-geometry when the NiO sputtering power was increased above 90 W. The composite crystalline films show different gas-sensing conduction types which are highly dependent on the Ni composition in the composite films. A Ni content of 10.5 at% is an optimal composition for the composite film to obtain superior ethanol gas-sensing performance in comparison with other composite films and pristine ZnO and NiO films. This is attributable to the formation of a suitable number of p–n junctions in the composite film which enhanced its ethanol gas-sensing performance. The experimental results herein demonstrate that manipulation of the ZnO and NiO relative phase content in the composite films through a cosputtering crystal growth process is a promising method to design oxide composite thin-film gas sensors with satisfactory performance.

中文翻译：

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Ni含量对陶瓷ZnO和NiO靶材射频共溅射生长ZnO-NiO p-n复合薄膜气敏性能的影响

在这项研究中，通过射频共溅射陶瓷ZnO和NiO靶材来生长双相ZnO-NiO p-n复合薄膜。在共溅射薄膜生长期间，NiO的溅射功率在50W至110W之间变化，而ZnO的溅射功率在此固定为120W。组成分析表明，复合膜中的Ni含量随NiO溅射功率的变化而变化，为3.6〜23.7at％。结构分析表明，NiO溅射功率大大改变了复合膜中的相对相含量。此外，复合膜的表面形态和晶粒尺寸高度依赖于NiO溅射功率。当NiO溅射功率增加到90 W以上时，表面晶粒尺寸增加并且其形态变为大的金字塔立体几何形状。复合晶体膜显示出不同的气敏传导类型，其高度依赖于复合膜中的Ni组成。与其他复合膜以及原始的ZnO和NiO膜相比，Ni含量为10.5 at％是获得最佳乙醇气敏性能的复合膜最佳组成。这归因于在复合膜中形成了适当数量的p–n结，从而增强了其乙醇气敏性能。本文的实验结果表明，通过共溅射晶体生长过程控制复合膜中ZnO和NiO的相对相含量是设计具有令人满意性能的氧化物复合薄膜气体传感器的一种有前途的方法。