Physical properties of RF sputtered ITO thin films and annealing effect
Physical properties of RF sputtered ITO thin films and annealing effect
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DOI：
10.1088/0022-3727/39/1/027
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发表时间：
2006-01-07
影响因子：
3.4
通讯作者：
Rémiens, D
中科院分区：
文献类型：
--
作者：
Kerkache, L;Layadi, A;Rémiens, D
研究了射频溅射In_2O_3：Sn（ITO）薄膜的结构、电学和光学性质以及沉积后退火的影响。厚度范围为225至862 nm。通过X射线衍射、扫描电子显微镜（SEM）和原子力显微镜（AFM）等测试手段对样品的结构和表面形貌进行了研究。我们发现，较薄的薄膜具有< 100 >纹理，并且随着薄膜的生长，优选取向从到变化< 100 >< 111 >。晶格参数大于体相参数，表明样品处于拉应力状态。晶粒尺寸随着厚度的增加而增加。SEM图像显示了具有不同形状和尺寸的晶粒的致密粒状结构。从AFM图像，平均表面粗糙度（rms）估计为3.89 nm。当t从225 nm增加到866 nm时，禁带宽度从3.65 eV减小到3.50 eV.在空气中，在100-500摄氏度范围内的温度T下进行退火实验。我们发现< 111 >退火处理后，织构变得更强。观察到晶粒尺寸随着T的增加而大幅增加。晶格常数随着T减小而变得更接近体值，即退火似乎减轻了沉积膜中存在的应力; T = 400摄氏度似乎是实际上获得无应力样品的最佳温度。我们观察到退火后电阻率p的大幅下降。在500 ℃退火的699 nm厚样品中注意到最低p值（16 × 10（-4）Ω cm）。p的降低似乎是较大的晶粒尺寸和较强的织构的结果< 111 >。
The structural, electrical and optical properties of RF sputtered In2O3 : Sn (ITO) thin films and the effect of post-deposition annealing have been studied. The thickness ranges from 225 to 862 nm. X-ray diffraction, scanning electron microscopy (SEM) and atomic force microscopy (AFM) experiments were performed to study the structure and the surface morphology of these samples. We found that thinner films have a < 100 > texture and as the film grows the preferred orientation changes from < 100 > to < 111 >. The lattice parameters are found to be larger than the bulk value, indicating that the samples are under a tensile stress. The grain size increases with increasing thickness. SEM images show a dense granular structure with grains having different shapes and sizes. From AFM images, the average surface roughness (rms) was estimated to be 3.89 nm. The energy gap was found to decrease from 3.65 to 3.50 eV as t increases from 225 to 866 nm. Annealing experiments were done, in the air, at temperature T in the 100-500 degrees C range. We found that the < 111 > texture becomes stronger after the annealing treatment. A large increase of the grain size with increasing T is observed. The lattice constant decreases with T to become closer to the bulk value, i.e. annealing seems to relieve the stress present in the as-deposited films; T = 400 degrees C seems to be the best temperature to obtain practically a stress free sample. We observe a large decrease in the electrical resistivity p after annealing. The lowest p value (16 x 10(-4) Omega cm) was noted in the 699 nm thick sample annealed at 500 degrees C. The decrease of p seems to be the consequence of a larger grain size and a stronger < 111 > texture.