Ogurcovs Andrejs, Kadiwala Kevon, Sledevskis Eriks, Krasovska Marina, Mizers Valdis
Institute of Solid State Physics, University of Latvia, Kengaraga Street 8, LV-1063 Riga, Latvia.
G. Liberts' Innovative Microscopy Centre, Department of Technology, Institute of Life Sciences and Technology, Daugavpils University, Parades Street 1A, LV-5401 Daugavpils, Latvia.
Sensors (Basel). 2022 Nov 12;22(22):8744. doi: 10.3390/s22228744.
This research presents a comparative analysis of water-gated thin film transistors based on a copper oxide (CuO) semiconductor in the form of a smooth film and a nanostructured surface. A smooth CuO film was deposited through reactive magnetron sputtering followed by annealing in atmosphere at a temperature of 280 ∘C. Copper oxide nanostructures were obtained by hydrothermal synthesis on a preliminary magnetron sputtered 2 nm thick CuO precursor followed by annealing at 280 ∘C. An X-ray diffraction (XRD) analysis of the samples revealed the presence of a tenorite (CuO) phase with a predominant orientation of (002). Scanning electron microscopy (SEM) and atomic force microscopy (AFM) studies of the samples revealed a highly developed surface with crystallites having a monoclinic syngony and dimensions of 15-20 nm in thickness, 150 nm in length, and 100 nm in height relative to a 2.5 nm height for the CuO crystallites of the smooth film. Electric measurements of the studied devices revealed typical current-voltage characteristics of semiconductors with predominant hole conductivity. The maximum ON/OFF ratio at a rain-source voltage of 0.4 volts and -1.2 volts on the gate for a smooth film was 102, and for a nanostructured transistor, it was 103. However, a much stronger saturation of the channel was observed for the nanostructured channel than for the smooth film. A test solution containing glyphosate dissolved in deionized water in three different concentrations of 5, 10, and 15 μmol/L was used during the experiments. The principle of operation was based on the preliminary saturation of the solution with Cu ions, followed by the formation of a metal-organic complex alongside glyphate. The glyphosate contents in the analyte led to a decrease in the conductivity of the transistor on the axis of the smooth film. In turn, the opposite effect was observed on the nanostructured surface, i.e., an increase in conductivity was noted upon the introduction of an analyte. Despite this, the overall sensitivity of the nanostructured device was twice as high as that of the device with a thin film channel. The relative changes in the field-effect transistor (FET) conductivity at maximum glyphosate concentrations of 15 μmol/L reached 19.42% for the nanostructured CuO film and 3.3% for the smooth film.
本研究对基于氧化铜（CuO）半导体的水门控薄膜晶体管进行了比较分析，该晶体管以光滑薄膜和纳米结构表面的形式存在。通过反应磁控溅射沉积光滑的CuO薄膜，然后在280℃的气氛中退火。通过水热合成在初步磁控溅射的2nm厚CuO前驱体上获得氧化铜纳米结构，然后在280℃退火。对样品的X射线衍射（XRD）分析表明存在具有（002）为主取向的黑铜矿（CuO）相。对样品的扫描电子显微镜（SEM）和原子力显微镜（AFM）研究表明，相对于光滑薄膜的CuO微晶2.5nm的高度，其表面高度发达，微晶具有单斜晶系，厚度为15 - 20nm，长度为150nm，高度为100nm。对所研究器件的电学测量揭示了具有主要空穴传导性的半导体的典型电流 - 电压特性。对于光滑薄膜，在栅极上0.4伏和 - 1.2伏的漏源电压下，最大开/关比为102，对于纳米结构晶体管，为103。然而，观察到纳米结构沟道的沟道饱和比光滑薄膜要强得多。实验期间使用了含有草甘膦的测试溶液，该溶液溶解在去离子水中，浓度分别为5、10和15μmol/L三种不同浓度。操作原理基于溶液先用铜离子饱和，然后与草甘膦一起形成金属 - 有机配合物。分析物中的草甘膦含量导致光滑薄膜轴向上晶体管的电导率降低。反过来，在纳米结构表面观察到相反的效果，即引入分析物后电导率增加。尽管如此，纳米结构器件的整体灵敏度是具有薄膜沟道器件的两倍。对于纳米结构的CuO薄膜，在最大草甘膦浓度为15μmol/L时，场效应晶体管（FET）电导率的相对变化达到19.42％，对于光滑薄膜为3.3％。
