脉冲激光沉积法(PLD)制备InGaN薄膜的膜厚分布特征

【目的】探究脉冲激光沉积法(PLD)制备InGaN薄膜时薄膜的厚度分布规律,以便于能够改善薄膜的均匀性。【方法】在实际情况中,靶材和基片并不平行,取任一无限小面积元近似作为平行靶材时的情况来分析,研究此处各项等效参数即可得到该处的膜厚。【结果】当靶材与基片的倾斜角为0°时,靶材激光照射点处的法线与基片相交处的膜厚度最大,以该点为中心,基片两侧膜厚呈对称分布,且越远离基片中心点,膜的厚度越小;当靶材与基片的倾斜角不为0°时,基片左右两侧膜厚不对称分布,靠近靶材一侧的薄膜厚度大于远离靶材一侧的薄膜厚度,倾斜角越大,两侧膜厚的差异越大,膜厚最大的点不在基片中心处,而是偏向靠近靶材的一端,倾斜角越大,偏离越明显。靶基距增大,所形成的膜厚度均匀性提高,但与靶基距较小时相比,相同时间内沉积的膜厚度要低得多。【结论】PLD制备InGaN薄膜过程中,基片各处上的薄膜受倾斜角和靶基距的影响,厚度不均匀,存在一个厚度分布。

Thickness Distribution of InGaN Films Grown by Pulsed Laser Deposition

Objective] In order to improve the thickness uniformity, the thickness distribution of the thin film was investigated by the pulse laser deposition (PLD) method to prepare the InGaN film.Methods] In practice, there was always a deflection angle between target and substrate. When any infinitesimal area element was used as a parallel target, we could get the thickness of the film when we studied all the equivalent parameters.Results] When the inclination angle between the target and the substrate was 0°, the film thickness at the origin O (The point at which the normal line of laser irradiation intersected the substrate) was largest, and the film thickness was symmetrical on both sides of the substrate distribution, the farther away from the origin O, the smaller the thickness of the film. When the inclination angle was not 0°, the film thickness was asymmetric, the thickness near the target side was larger than that away from the target side, and the greater the inclination angle, the greater the difference between the two sides of the film thickness. Correspondingly, the largest point of the film thickness was not at the center of the substrate, which biased toward the end of the target, the greater the inclination angle, the more obvious deviation. The uniformity of the film thickness was improved but the deposited film thickness was much lower when the target-substrate distance increased.Conclusion] In the process of preparing InGaN thin films by PLD, the films on the substrate were affected by the tilt angle and the target-substrate distance. The thickness was not uniform and there was a thickness distribution.