Department of Physics and Astronomy, College of Science, King Saud University, Riyadh, 11451, Saudi Arabia.
Department of Physics and Astronomy, College of Science, King Saud University, Riyadh, 11451, Saudi Arabia.
Appl Radiat Isot. 2022 Aug;186:110225. doi: 10.1016/j.apradiso.2022.110225. Epub 2022 May 5.
In this study, we investigated the effect of the thickness of metal-dioxide thin films on silicon (Si) micro-electromechanical systems (MEMS) for sensitive, accurate, and reproducible detection of gamma-radiation dose. Silicon wafers and microcantilevers were coated with various thicknesses of titanium dioxide (TiO) thin films and controlled by the number of cycles in atomic layer deposition (ALD) under 17-mbar pressure and temperature of 200 °C. All samples were exposed to different doses of gamma (0, 10, and 20 kGy) using aCo source. Before and after gamma irradiation, the optical and mechanical properties of the TiO thin films on Si wafers were studied by spectroscopic ellipsometry (SE) and atomic force microscopy (AFM). The resonance frequency shift (RFS) resulting from exposing different thicknesses of TiO thin films on MEMS-based cantilevers to gamma-radiation doses were evaluated by AFM. SE results revealed the film thicknesses of 11.91, 21.77, 62.91, and 218.23 nm at 250, 500, 1250, and 2500 coating cycles, respectively. Through SE, other optical constants, such as surface roughness (SR) and refractive index (n), were obtained. The root-mean-square (RMS) SR obtained from AFM images and SE measurements on Si wafers showed the same behavior under gamma radiation according to the TiO thin-films thicknesses. The RFS results show that the best film thickness for reproducible and sensitive gamma-radiation detection was 218.23 nm. The frequency shift as the gamma dose increase from 0 to 20 kGy was ∼60 Hz. It is a very palpable and linear shift; hence, it can be used as a dosimeter sensor. The results were verified by the statistical correlation coefficient method to find the correlation between RFS and the gamma dose at different film thicknesses. Correlation results are consistent with other results.
在这项研究中，我们研究了金属氧化物薄膜的厚度对硅（Si）微机电系统（MEMS）的影响，以实现对伽马辐射剂量的敏感、准确和可重复检测。硅片和微悬臂梁涂覆有不同厚度的二氧化钛（TiO）薄膜，并通过在 17 毫巴压力和 200°C 温度下控制原子层沉积（ALD）的循环次数来控制。所有样品均使用 Co 源暴露于不同剂量的伽马辐射（0、10 和 20 kGy）下。在伽马辐照前后，通过光谱椭圆术（SE）和原子力显微镜（AFM）研究了 Si 晶片上 TiO 薄膜的光学和机械性能。通过 AFM 评估了不同厚度的 TiO 薄膜在基于 MEMS 的悬臂梁上暴露于伽马辐射剂量后导致的共振频率位移（RFS）。SE 结果显示，在 250、500、1250 和 2500 个镀膜循环时，薄膜厚度分别为 11.91、21.77、62.91 和 218.23nm。通过 SE 还获得了其他光学常数，例如表面粗糙度（SR）和折射率（n）。从 AFM 图像和 Si 晶片上的 SE 测量获得的 RMS SR 表现出与 TiO 薄膜厚度相同的行为。RFS 结果表明，对于可重复和敏感的伽马辐射检测，最佳的薄膜厚度为 218.23nm。随着伽马剂量从 0 增加到 20 kGy，频率偏移约为 60 Hz。这是一个非常明显和线性的偏移，因此可以用作剂量计传感器。通过统计相关系数法验证了结果，以找到不同薄膜厚度下 RFS 与伽马剂量之间的相关性。相关结果与其他结果一致。
