Effect of gamma irradiation dose on the structure and pH sensitivity of ITO thin films in extended gate field effect transistor
Effect of gamma irradiation dose on the structure and pH sensitivity of ITO thin films in extended gate field effect transistor
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DOI：
10.1016/j.rinp.2018.10.066
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发表时间：
2019-03-01
影响因子：
5.3
通讯作者：
Sulieman, A.
中科院分区：
文献类型：
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作者：
Ali, Amal Mohamed Ahmed;Ahmed, Naser M.;Sulieman, A.
尽管几项研究已经证明了氧化铟锡（ITO）作为扩展栅场效应晶体管（EGFET）的用途，但尚未考虑不同剂量的γ辐射对ITO膜的固有性质的影响。本文研究了γ辐照对ITO薄膜的结构、光学、形貌和电学性能以及pH敏感性（作为扩展栅场效应晶体管）的影响。采用射频溅射技术制备了厚度为400 nm的ITO薄膜。然后使样品经受来自Co-60放射性同位素的各种剂量的γ辐射（0.5kGy、lkGy、1.5kGy和2kGy）。利用X射线衍射（XRD）、原子力显微镜（AFM）、场发射扫描电子显微镜（FESEM）和紫外-可见分光光度计分析了辐照前后薄膜的结构和形貌变化以及透射和吸收光谱。然后将辐照的ITO薄膜用作扩展栅场效应晶体管，以确定其作为pH传感器提高灵敏度的能力。ITO薄膜在300-900 nm范围内的晶粒尺寸和透射率随着γ辐照剂量的增加而减小。相比之下，ITO薄膜的均匀性和表面粗糙度随着γ辐射剂量的增加而增加，由于晶格缺陷的形成。此外，薄膜的电阻随着剂量的增加而增加，因为低电流密度和与辐照相关的大量表面缺陷。的ITO薄膜的pH敏感性改善照射后，可能是由于伴随的表面粗糙度增加，随着辐射剂量的增加。ITO薄膜的pH敏感性在辐照后的改善证明了它们作为pH传感器的潜在用途。
Even though several studies have demonstrated the use of Indium Tin Oxides (ITO) as an extended gate field effect transistor (EGFET), the effect of different doses of gamma radiation on the intrinsic properties of the ITO films has not been considered. This study investigates the effect of gamma irradiation on the structural, optical, morphological and electrical properties as well as pH sensitivity (as an extended gate field effect transistor) of ITO thin films. ITO thin films with thickness of 400 nm were prepared using a radio frequency sputtering technique. The samples were then subjected to various doses of gamma radiation from a Co-60 radio-isotope (0.5 kGy, 1 kGy, 1.5 kGy, and 2 kGy). The structural and morphological changes as well as transmission and absorption of the thin films were analyzed using X-ray diffraction (XRD), Atomic Force Microscopy (AFM), Field-Emission Scanning Electron Microscope (FESEM) and UV-Vis spectrophotometry, before and after irradiation. The irradiated ITO thin films were then used as an extended gate field effect transistor to determine its ability to improve sensitivity as pH sensors. The grain size and transmittance in the range 300-900 nm of the ITO films were found to decrease with increasing gamma irradiation dose. In contrast, the uniformity and surface roughness of ITO thin films increased with increasing gamma radiation dose due to the formation of lattice defects. Moreover, the electrical resistance of the thin films increased with increasing dose because of the low current density and high number of surface defects associated with irradiation. The pH sensitivity of the ITO thin films improved after irradiation, possibly due to the concomitant increase in surface roughness with increasing radiation dose. The improvements in the pH sensitivity of ITO thin films after irradiation justify their potential use as pH sensors.