Abstract In this work, the impact of surface defects in zinc oxide (ZnO) thin films on the performance of field effect transistor (FET) biosensors has been explored. Here, ZnO thin films have been fabricated using electron beam evaporation with various deposition parameters to tune the surface roughness and defect state density. The films have been deployed for sensing prostate specific antigen (PSA) after anti-PSA antibody immobilization. Interestingly, it has been observed that though the transconductance of the sensors degrade monotonically with increasing defect density, the antibody binding density has a non-monotonic behaviour due to enhanced steric hindrance effect beyond a certain limit of surface roughness. There is a variation of sensitivity by 15 times with different physical properties of ZnO and the optimized sensor has a PSA detection limit of 0.06 fM. Further, the sensor with the best sensitivity retains its performance upto 2 months while a non-optimized sensor with initial PSA detection limit of 0.1 fM has longevity of 4 months. Thus, it can be envisaged that tuning the surface defect state in ZnO FET biosensor is an essential requirement not only to ensure a low detection limit and high sensitivity but also to assure a reliable long term performance.

中文翻译：

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电子束蒸发氧化锌薄膜表面缺陷对 FET 生物传感特性的影响，以实现可靠的 PSA 检测

摘要 在这项工作中，研究了氧化锌 (ZnO) 薄膜表面缺陷对场效应晶体管 (FET) 生物传感器性能的影响。在这里，已经使用电子束蒸发和各种沉积参数来调整表面粗糙度和缺陷态密度来制造 ZnO 薄膜。这些薄膜已用于在抗 PSA 抗体固定后感测前列腺特异性抗原 (PSA)。有趣的是，已经观察到，尽管传感器的跨导随着缺陷密度的增加而单调降低，但由于超过一定的表面粗糙度限制，增强的空间位阻效应，抗体结合密度具有非单调行为。ZnO 物理性质不同，灵敏度有 15 倍的变化，优化后的传感器的 PSA 检测限为 0.06 fM。此外，具有最佳灵敏度的传感器可保持其性能长达 2 个月，而初始 PSA 检测限为 0.1 fM 的非优化传感器的使用寿命为 4 个月。因此，可以设想调整 ZnO FET 生物传感器中的表面缺陷状态不仅是确保低检测限和高灵敏度的基本要求，而且是确保可靠的长期性能的必要条件。