過渡金屬二硫族化物 (Transition-metal dichalcogenides,TMDCs) 其結構為二維層狀之材料，具有多樣的電性，如絕緣體、半導體、金屬態。其中 n 型半導體特性的二硫化鎢具有非常高的電流開關比，非常適合做為離子感測電晶體之通道材料，進而可以減少感測器之誤判率。本論文研究以二硫化鎢為通道的雙閘極離子感測電晶體，量測WS2之基礎電性發現其具有約 7個電流開關比，以及其最大電流0.402μA/μm，且利用上下閘極間的電容耦合效應，使感測靈敏度得以大幅提升，其靈敏度突破能斯特(Nernst)極限 59.6 mV/pH，靈敏度值高達 153.1 mV/pH。與上閘極之離子液體接觸的銀-氯化銀之微小參考電極是以電解法自行製造，其電極在不同的pH值緩衝液所呈現的氧化還原電位之趨勢與商用的銀-氯化銀參考電極表現出高度線性，其表示自行電解之銀-氯化銀參考電極有著極高的品質與穩定性，其優點可進行微量量測。透過 Keithley4200機台控制參考電極與pH緩衝液間的距離，排除不必要的實驗變因，不需要將整個元件浸泡至離子緩衝液中。結論而言，以二硫化鎢為通道的離子感測電晶體，具優異的感測特性，可望未來應用在生物感測領域。

Transition-metal dichalcogenides (TMDCs) are two-dimensional layered materials, which have a diversity of electrical properties, such as insulators, semiconductors, and metallic states. Among them,Among them, character- ization of n-type semiconducting tungsten disulfide (WS2) has extremely high on-off ratio, which is suitable for being the channel material of ISFET. It can reduce the misjudgement rate of the sensor. In this paper, we demon- strate a double-gate ion-sensitive FET with WS2 as a channel. Measuring the fundamental electrical properties of WS2, we found out that it has about 7 order on-off ratio, and the maximum on current is 0.402uA/um.Using ca- pacitive coupling between the top and back gate to improve the sensitivity substantially. The sensitivity of our device reaches up to 153.1 mV/pH, which is capable of surpassing the maximum achievable voltage sensitivity for pH sensing of value 59.6 mV/pH. The hand-made Ag/AgCl reference electrode contacted with electrolyte on the top gate is fabricated with the electrochemical method. The hand-made electrode performs high linear- ity on the Shifted Voltage as well as the commercial reference electrode in buffer solution of different pH values, which indicates that the hand-made Ag/AgCl electrode has high quality and stability that is advantageous for micro-measurement. By controlling the pin of Keithley4200, we can mod- ulate the distance between the pH buffer solution and the reference elec- trode to eliminate unnecessary experimental variables. It is not necessary to immerse the entire component in the buffer solution. In conclusion, the ion-sensitive transistor using WS2 as the channel has excellent sensing prop- erties, which is hopefully applied in the field of biosensing in the future.

[1] J. Bardeen and W. H. Brattain, “The transistor, a semi-conductor triode,” Physical Review, vol. 74, no. 2, p. 230, 1948.
[2] “60 年前芯往事，第一個萬億美元初創企業的傳奇歷程,” 2021. https://reurl.cc/ ROO2dr.
[3] P.Bergveld,“Developmentofanion-sensitivesolid-statedeviceforneurophysiolog- ical measurements,” IEEE Transactions on biomedical engineering, no. 1, pp. 70–71, 1970.
[4] M. Kaisti, “Detection principles of biological and chemical fet sensors,” Biosensors and Bioelectronics, vol. 98, pp. 437–448, 2017.
[5] D. Rani, V. Pachauri, N. Madaboosi, P. Jolly, X.-T. Vu, P. Estrela, V. Chu, J. P. Conde, and S. Ingebrandt, “Top-down fabricated silicon nanowire arrays for field- effect detection of prostate-specific antigen,” ACS omega, vol. 3, no. 8, pp. 8471– 8482, 2018.
[6] Y.HuandP.Georgiou,“Arobustisfetph-measuringfront-endforchemicalreaction monitoring,” IEEE Transactions on Biomedical Circuits and Systems, vol. 8, no. 2, pp. 177–185, 2014.
[7] G. Fiori, F. Bonaccorso, G. Iannaccone, T. Palacios, D. Neumaier, A. Seabaugh, S. K. Banerjee, and L. Colombo, “Electronics based on two-dimensional materials,” Nature nanotechnology, vol. 9, no. 10, pp. 768–779, 2014.
[8] K. S. Novoselov, A. K. Geim, S. V. Morozov, D.-e. Jiang, Y. Zhang, S. V. Dubonos, I. V. Grigorieva, and A. A. Firsov, “Electric field effect in atomically thin carbon films,” science, vol. 306, no. 5696, pp. 666–669, 2004.
[9] M. Chhowalla, H. S. Shin, G. Eda, L.-J. Li, K. P. Loh, and H. Zhang, “The chem- istry of two-dimensional layered transition metal dichalcogenide nanosheets,” Na- ture chemistry, vol. 5, no. 4, pp. 263–275, 2013.
[10] C. Ataca, H. Sahin, and S. Ciraci, “Stable, single-layer mx2 transition-metal oxides and dichalcogenides in a honeycomb-like structure,” The Journal of Physical Chem- istry C, vol. 116, no. 16, pp. 8983–8999, 2012.
[11] Q. H. Wang, K. Kalantar-Zadeh, A. Kis, J. N. Coleman, and M. S. Strano, “Elec- tronics and optoelectronics of two-dimensional transition metal dichalcogenides,” Nature nanotechnology, vol. 7, no. 11, pp. 699–712, 2012.
[12] H. Yuan, H. Wang, and Y. Cui, “Two-dimensional layered chalcogenides: from ra- tional synthesis to property control via orbital occupation and electron filling,” Ac- counts of chemical research, vol. 48, no. 1, pp. 81–90, 2015.
[13] J. A. Wilson and A. Yoffe, “The transition metal dichalcogenides discussion and interpretation of the observed optical, electrical and structural properties,” Advances in Physics, vol. 18, no. 73, pp. 193–335, 1969.
[14] A.Kuc,N.Zibouche,andT.Heine,“Influenceofquantumconfinementontheelec- tronic structure of the transition metal sulfide t s 2,” Physical Review B, vol. 83, no. 24, p. 245213, 2011.
[15] L. Tang, J. Tan, H. Nong, B. Liu, and H.-M. Cheng, “Chemical vapor deposition growth of two-dimensional compound materials: controllability, material quality, and growth mechanism,” Accounts of Materials Research, vol. 2, no. 1, pp. 36–47, 2020.
[16] Y. Zhang, Y. Zhang, Q. Ji, J. Ju, H. Yuan, J. Shi, T. Gao, D. Ma, M. Liu, Y. Chen, et al., “Controlled growth of high-quality monolayer ws2 layers on sapphire and imaging its grain boundary,” ACS nano, vol. 7, no. 10, pp. 8963–8971, 2013.
[17] N.Peimyoo,J.Shang,W.Yang,Y.Wang,C.Cong,andT.Yu,“Thermalconductivity determination of suspended mono-and bilayer ws2 by raman spectroscopy,” Nano Research, vol. 8, no. 4, pp. 1210–1221, 2015.
[18] N.Peimyoo,J.Shang,C.Cong,X.Shen,X.Wu,E.K.Yeow,andT.Yu,“Nonblink- ing, intense two-dimensional light emitter: monolayer ws2 triangles,” ACS nano, vol. 7, no. 12, pp. 10985–10994, 2013.
[19] “金氧半二極體、電晶體及其電性討論,” 2014. https://reurl.cc/mZmeE9.
[20] P. Bergveld, “Thirty years of isfetology: What happened in the past 30 years and what may happen in the next 30 years,” Sensors and Actuators B: Chemical, vol. 88, no. 1, pp. 1–20, 2003.
[21] D.Ovchinnikov,A.Allain,Y.-S.Huang,D.Dumcenco,andA.Kis,“Electricaltrans- port properties of single-layer ws2,” ACS nano, vol. 8, no. 8, pp. 8174–8181, 2014.
[22] H.-J.Jang,J.-G.Gu,andW.-J.Cho,“Sensitivityenhancementofamorphousingazno thin film transistor based extended gate field-effect transistors with dual-gate opera- tion,” Sensors and Actuators B: Chemical, vol. 181, pp. 880–884, 2013.