本論文旨在製備具多重粗化奈米結構NiO/MWCNT感測電極(Sensing electrodes, SEs)及其於pH感測器之應用研究。利用適化的濕式蝕刻製程於p-Si (100)基板(Planar-Si)上製備出金字塔紋理表面粗化Si基板(Pyramid-Si)，提供較大表面積(Surface area, SA)作為感測材料之沉積或成長；並依序藉由噴塗沉積(Spray deposition)及水熱成長(Hydrothermal growth, HTG)技術於Pyramid-Si基板上分別沉積多壁奈米碳管(Multi-walled carbon nanotubes, MWCNTs)與成長氧化鎳(Nickel oxide, NiO)奈米片(Nanosheets, NSs)，製備具多重表面粗化結構(NiO NSs/MWCNTs/Pyramid-Si)之SEs；同時結合延伸閘極場效電晶體(Extended-gate field-effect transistor, EGFET)之配置，應用於具高感測性能pH-EGFET感測器之研究開發。
本論文之研究工作主要分為三部分：第一部分為建構於平面矽(Planar-Si)基板與具Pyramid-Si平台之MWCNTs感測材料製備及其於pH感測特性之研究。研究過程中，首先，使用5 wt%氫氧化鉀(KOH)與7 wt%異丙醇(IPA)混和溶液於Planar-Si基板上分別以85、90及95 °C溫度下進行40 min濕式蝕刻製程，以製備出具不同表面粗化結構Pyramid-Si基板；實驗結果顯示，相於Planar-Si基板，於90 °C-KOH蝕刻的Pyramid-Si基板具有最大之表面積增益(Surface area gain, SAG)約為2.31(大於理想角錐體之1.732)，主要歸因於所形成為不規則或無序的角錐體形狀，於Si (111)晶面上呈現出介於大角錐體間底面與大小高度不同的重疊角錐體所致。
使用噴塗法於Planar-Si與90 °C-KOH蝕刻之Pyramid-Si基板上分別進行80、120、160及200 spray-times (cycles)之MWCNTs薄膜沉積作為感測材料，分別製備出不同噴塗層數之MWCNTs/Planar-Si (Devices A)及MWCNTs/Pyramid-Si (Devices B) SEs，並應用於pH-EGFET感測特性之量測分析與探討。實驗結果顯示，於Device A SEs中，Device A-200 times展現出最優異之pH感測靈敏度(52.53 mV/pH)，主要歸因於MWCNTs沉積於Planar-Si之網狀結構膜厚(或SA)隨著spray-times的增加而增加，可提供較大SA(較多活化位址)作為pH溶液中H+(或OH‒)之吸附。值得一提的是，於相同spray-times下，Devices B (MWCNTs/ Pyramid-Si)的感測靈敏度(160次之試片為54.95 mV/pH)均優於Devices A (MWCNTs/ Planar-Si)的感測靈敏度(160次之試片為52.15 mV/pH)，證實基板表面粗化工程在pH感測扮演了重要的角色，進而能獲得相對較大SA的MWCNTs；於Device A SEs中，雖然網狀結構MWCNT之膜厚會隨著spray-times的增加而增大，然而於所製備MWCNTs/ Pyramid-Si SEs中，以Device B-160 times展現出最佳之pH感測靈敏度(54.95 mV/pH)，主要歸因於在Pyramid-Si基板160 times之MWCNTs沉積後仍能維持與Pyramid-Si平台底部錐體之共形架構，因而具有最大感測SA以及呈現出最佳pH感測靈敏度。
第二部分旨在針對上述Device B-160 times SE輔以熱氧化處理(於O2氛圍下分別以300、400、500及600 °C溫度進行1 h熱退火製程)，以優化MWCNT之晶體品質及/或增加額外含氧官能基團之鍵結位址數量，進一步改善pH感測靈敏度。實驗結果顯示，相較於未退火之Device B-160 times (54.95 mV/pH)，500 °C-Device B-160 times呈現較佳之pH感測靈敏度(56.45 mV/pH)，主要歸因於500 °C的熱退火製程可提供適當的熱預算使C=C鍵結斷裂並與氧化合而於CNTs表面產生較多的含氧官能基團(如C‒O與O‒C=O)，CNTs表面額外增加帶負電的活化位址數量有助於pH緩衝液中H+的吸附，因此造成pH感測靈敏度之提升。
第三部分旨在利用水熱法以70 mM之Ni(NO3)2·6H2O與70 mM之C6H12N4混合溶液於500 °C-Device B-160 times SE之MWCNTs上在90 °C進行5、7、9及11 h之HTG製程以成長 NiO NSs，以製備出具多重表面粗化結構NiO NSs/MWCNTs/Pyramid-Si (Devices C)之SEs，並應用於pH感測特性之量測分析與探討。實驗結果顯示，Device C-9 h SE展現出最佳之靈敏度(57.56 mV/pH)，主要歸因於9 h的最適化HTG製程可成長出較大SA之NiO NSs並使多重表面粗化結構(NiO NSs/ MWCNTs/ Pyramid-Si)感測材料SA極大化外，同時也基於NiO與MWCNT二種不同感測材料之互補屬性，於較低(較高)pH值緩衝液中所分別呈現出較高ΔV的正(負)電位差異，使其pH感測靈敏度由56.45 mV/pH (500 °C-Device B)進一步提升至57.56 mV/pH (Device C-9 h)。然而，在穩定度方面，相較於Device B-160 times (5.81mV)與500 °C-Device B (6.42 mV)，顯現較大的遲滯電壓(7.12 mV)，應可歸因於多重表面粗化結構雖具有較高SA，但相對地因材料粗化過程造成材料表面具有更多缺陷，導致其已吸附之離子要脫附至溶液中之顯得更為困難，使其感測靈敏度與穩定度呈現trade-off的關係。
本論文所提以適化濕式蝕刻製程所形成Pyramid-Si基板可提供較大SA作為感測材料之工作平台，結合適化的噴鍍製程所沉積MWCNTs與HTG製程所成長NiO NSs等具高SVR奈米結構感測材料所製備具多重粗化NiO NSs/MWCNTs/Pyramid-Si之SE，應用於pH-EGFET感測器展現出接近能斯特響應(Nernstian response, 室溫下59.14 mV/pH)之高感測靈敏度(57.56 mV/pH)、優異線性度(0.999)與穩定性等優越感測性能；同時元件之製備亦具有製程簡易、成本低廉及可大面積製備等優點，適合商業規模化生產，預期本所提出具多重表面粗化結構pH-EGFET感測器之研究於未來pH感測器之應用將極具潛力。

This thesis focuses on the fabrication of high performance sensing electrodes (SEs) based on nickel oxide (NiO)/multi-walled carbon nanotubes (MWCNTs) on a Si platform with a multiple surface roughening scheme and their application in pH sensors. The use of a suitable wet chemical etching process to prepare a surface roughened Si substrate with a pyramidal cones (pyramid-Si) on p-Si(100) substrates (called planar-Si) is proposed to increase the surface area (SA) of the Si platform for the deposition or growth of sensing materials. Sensing materials of MWCNTs and NiO nanosheets (NSs) were sequentially deposited and grown on the KOH-etched Si substrates using a spray deposition method and hydrothermal growth (HTG) technique, respectively, to prepare SEs with multiple roughening surface structures (i.e., NiO NSs/MWCNTs/pyramid-Si). The sensing performance of the prepared SEs with an extended-gate field-effect transistor (EGFET) configuration are measured and analyzed.
The contents of the present thesis are divided into three sections, which are described as follows:
In the first section, MWCNT-type SEs based on MWCNTs sensing material deposited on a planar-Si and a pyramid-Si substrates and their pH sensing performances are proposed and analyzed. To clarify the effect of the temperature of etching solution on the surface morphology of KOH-etched Si substrate, p-Si (100) wafers were subjected to a wet anisotropic chemical etching using a mixing solution of KOH (5 wt%) and isopropyl alcohol (7 wt%) at 85, 90, and 95 °C, respectively, for 40 min. It is found that, as compared to the planar-Si substrate, the 90 °C-KOH-etched Si substrate shows the largest SA gain of about 2.31 (larger than 1.732 of an ideal perfect pyramidal cone), which is mainly due to the formation of irregular or distorted pyramidal cones with smaller sizes and higher bottoms at the valley of adjacent regions of large onces. To examine the influence of spraying time of the MWCNTs on the pH sensing performance, the SEs based on MWCNTs with different spraying cycles (80, 120, 160, and 200 times) on planar Si (device A) and a 90°C-KOH-etched Si substrates (device B) were prepared and discussed. For device A, the MWCNTs deposited by 200 cycles exhibits the best pH sensing sensitivity of 52.53 mV/pH, which is ascribed to the thickness of the MWCNT network structure increases with increasing the spraying time, it results in an increase in SA and activation sites to enhance the adsorption of the H+ (or OH‒). Note that, the SEs based on MWCNTs deposited on the 90°C-KOH-etched Si substrate shows a higher sensitivity than that of the planar-Si substrate for the same spray-cycles. It could be attributed to the 90°C-KOH-etched Si substrate provides a larger SA gain (2.31) to realize a higher SA of MWCNT, as compared to the planar Si substrate. For device B case, although the thickness of the MWCNTs thin films increases with the spray-cycles, MWCNTs deposited on a 90 °C-KOH-etched Si substrate with 160 cycles shows the best pH sensing sensitivity (54.95 mV/pH) among the prepared samples. It is primarily assigned to the shape of the as-sprayed MWCNT films after 80, 120 and 160 cycles still remain in conformity with KOH-etched Si substrate. Nevertheless, it is found that the MWCNT film sprayed with 200 cycles fails to keep conformity, which could be attributed to the formation of thicker coatings due to the excessive sprayed-times and resulted in deconformal to the bottom pyramidal cones on Si substrate.
In the second section, in order to confirm the effect of the thermal annealing temperature of annealed-MWCNT films on pH sensing performance, MWCNT-type SEs (Device B-160 times) based on thermal annealing at 300, 400, 500, and 600 °C were presented and discussed. Experimental results reveal that the SE based on 500 °C-annealed device B-160 time exhibits the best pH sensing sensitivity (56.45 mV/pH) among all the prepared samples, which mainly attributed to the MWCNTs sensing material after thermal annealing at 500 °C in O2 ambient could create more oxygen-containing functional groups (C‒O and O‒C=O) or defects on the surface of the MWCNTs, thus offering a larger number of active sites for adsorption of H+ and OH‒ ions. It suggests the purpose of appropriately thermal oxidation treatment could be beneficial to the sensing performance of pH sensors based on CNT.
In the third section, NiO NSs/MWCNT-type SEs (device C) based on NiO NSs synthesized on MWCNT of 500 °C-device B by using HTG technique were proposed and discussed. To elucidate the effect of HTG time on the morphology of NiO NSs and its pH sensing performance, the 500 °C-device B (160 times) was subjected to further deposition of NiO NSs using a chemical solution with 70 mM of Ni(NO3)2·6H2O and 70 mM of C6H12N4 at 90 °C for 5, 7, 9, and 11 h, respectively. Then, a thermal annealing was conducted in air at 400 °C for 40 min to transform the as-grown Ni(OH)2 NSs to NiO NSs. Experimental results reveal that, the device C-9 h exhibits the best pH sensitivity (57.56 mV/pH), which mainly due to the largest SA of NiO NSs was obtained from the HTG-9 h process, it also be attributed to the complementary properties between the NiO and CNT sensing materials, which generate a higher ΔV positive (negative) potential in a lower (higher) pH buffer solution for NiO and CNT, respectively. In additional, both the hysteresis and drift characteristics of the device C-9 h were measured to clarify the stability performance. Experimental results indicate that the hysteresis voltage shift and drift rate as low as 7.12 mV and 1.84 mV/h were obtained, suggesting that the proposed SE based on NiO NSs (9 h)/500 °C-MWCNT (160 cycles)/90 °C-KOH-etched Si substrate has a good repeatability and stability for pH sensig.
The high pH-EGFET sensing performance of SE based on NiO NSs/MWCNTs/KOH-etched Si platform is proposed and investigated in this thesis. It is expected that such a multiple surface roughening scheme could be very potential for advanced sensing applications in wide industry fields.

[1] M. Futagawa, T. Iwasaki, H. Murata, M. Ishida, and K. Sawada, "A miniature integrated multimodal sensor for measuring pH, EC and temperature for precision agriculture," Sensors, vol. 12, pp. 8338-8354, 2012.
[2] S. Jamasb, "Continuous monitoring of pH and blood gases using ion-sensitive field effect transistors operating in the amperometric mode in presence of drift," Biosensors, vol. 9, no. 1, pp. 44-1-44-12, 2019.
[3] G. K. Saba, E. Wright-Fairbanks, B. Chen, W. J. Cai, A. H. Barnard, C. P. Jones, C. W. Branham, K. Wang, and T. Miles, "The development and validation of a profiling glider deep ISFET-based pH sensor for high resolution observations of coastal and ocean acidification," Forntiers in Marine Science, vol. 6, pp. 664-1-664-17, 2019.
[4] A. Eftekhari, "pH sensor based on deposited film of lead oxide on aluminum substrate electrode," Sensors and Actuators B: Chemical, vol. 88, pp. 234-238, 2003.
[5] C.-H. Lu and T.-H. Hou, "High-performance double-gate α-InGaZnO ISFET pH sensor using a HfO2 gate dielectric," IEEE Transactions on Electron Devices, vol. 65, no. 1, pp. 237-242, 2018.
[6] K. B. Parizi, X. Xu, A. Pai, X. Hu, and H. S. Philip Wong, "ISFET pH sensitivity: counter-ions play a key role," Scientific Reports, vol.7, pp. 41305-1-41305-10, 2017.
[7] H. Cho, K. Kim, J. S. Yoon, T. Rim, M. Meyyappan, and C. K. Baek, "Optimization of signal to noise ratio in silicon nanowire ISFET sensors," IEEE Sensors Journal, vol. 17, no. 9, pp. 1-6, 2017.
[8] Y. Rayanasukha, S. Porntheeraphat, W. Bunjongpru, N. Khemasiri, A. Pankiew, W. Jeamsaksiri et al., "High sensitive nanocrystal titanium nitride EGFET pH sensor," Advanced Materials Research, vol. 802, pp. 232-236, 2013.
[9] I. Lauks, P. Chan, and D. Babic, "The extended gate chemically sensitive field effect transistor as multi-species microprobe," Sensors and Actuators, vol. 4, pp. 291-298, 1983.
[10] S. A. Pullano, C. D. Critello, I. Mahhub, N. T. Tasneem, S. Shamsir, S. K. Islam et al., "EGFET-based sensors for bioanalytical applications: a review," Sensors, vol. 18, pp. 4042-4065, 2018.
[11] Y.-H. Lin, C.-P. Chu, C.-F. Lin, H.-H. Tsai, and Y.-Z. Juang, "Extended-gate field-effect transistor packed in micro channel for glucose, urea and protein biomarker detection," Biomed Microdevices, vol. 17, pp. 111-1-111-9, 2015.
[12] N. M. Ahmed, E. A. Kabaa, M. S. Jaafar, and A. F. Omar, "Characteristics of extended-gate field-effect transistor (EGFET) based on porous n-type (111) silicon for use in pH sensors," Journal of Electronic Materials, vol. 46, pp. 5804-5813, 2017.
[13] A. Fulati, S. M. Ali, M. Riaz, G. Amin, O. Nur, and M. Willander, "Miniaturized pH sensors based on zinc oxide nanotubes/nanorods," Sensors, vol. 9, pp. 8911-8923, 2009.
[14] R. Zhao, M. Xu, J. Wang, and G. Chen, "A pH sensor based on the TiO2 nanotube array modified Ti electrode," Electrochimica Acta, vol. 55, pp. 5647-5651, 2010.
[15] S. P. Chang and T. H. Yang, "Sensing performance of EGFET pH sensors with CuO nanowires fabricated on glass substrate," International Journal of Electrochemical Science, vol. 7, pp. 5020-5027, 2012.
[16] C.-Y Kuo, S.-J. Wang, R.-M. Ko, and H.-H Tseng, "Super-nernstian pH sensors based on WO3 nanosheets," Japanese Journal of Applied Physics, vol. 57, pp. 1-8, 2018.
[17] H.-H. Li, W.-S. Dai, J.-C. Chou, and H.-C. Cheng, "An extended-gate field-effect transistor with low temperature hydrothermally synthesized SnO2 nanorods as pH sensor," IEEE Eelectron Device Letters, vol. 33, no. 10, pp. 1495-1497, 2012.
[18] E. M. Guerra, G. R. Silva, and M. Mulato, "Extended gate field effect transistor using V2O5 xerogel sensing membrane by sol-gel method," Solid State Sciences, vol. 11, pp. 456-460, 2009.
[19] D.-B. Kuang, B.-X. Lei, Y.-P. Pan, X.-Y. Yu, and C.-Y. Su, "Fabrication of novel hierarchical β-Ni(OH)2 and NiO microspheres via an easy hydrothermal process," Journal of Physical Chemistry C, vol. 113, pp. 5508-5513, 2009.
[20] X. Yan, X. Tong, J. Wang, C. Gong, M. Zhang, and L. Liang, "Hydrothermal-synthesized NiO nanowall array for lithium ion batteries," Journal of Alloys and Compounds, vol. 556, pp. 56-61, 2013.
[21] Q. Yang, J. Sha, X. Ma, and D. Yang, "Synthesis of NiO nanowires by a sol-gel process," Materials letters, vol. 59, pp. 1967-1970, 2005.
[22] S. Y. Wang, W. Wang, W. Z. Wang, and Y. W. Du, "Preparation and characterization of highly oriented NiO (200) films by a pulse ultrasonic spray pyrolysis method," Materials Science and Engineering B, vol. 90, pp. 133-137, 2002.
[23] Y. S. Chien, P. Y. Yang, W. L. Tasi, Y. R. Li, C. H. Chou, J. C. Chou, and H. C. Cheng, "The pH Sensing Characteristics of the extended-gate field-effect transistors of multi-walled carbon-nanotube thin film using low-temperature ultrasonic spray method," Journal of Nanoscience and Nanotechnology, vol. 12, pp. 5423-5428, 2012.
[24] Y. S. Chien, W. L. Tsai, I. C. Lee, J. C. Chou, and H. C. Cheng, "A novel pH sensor of extended-gate field-effect transistors with laser-irradiated carbon nanotube network," IEEE Electron Device Letters, vol. 33, no. 11, pp. 1622-1624, 2012.
[25] W. L. Tsai, B. T. Huang, K. Y. Wang, Y. C. Huang, P. Y. Yang, and H. C. Cheng, "Functionalized carbon nanotube thin films as the pH sensing membranes of extended-gate field-effect transistors on the flexible substrates," IEEE Electron Device Letters, vol. 13, no. 4, pp. 760-764, 2014.
[26] A. Kunz, "Electronic structure of NiO," Journal of Physics C: Solid State Physics, vol. 14, no. 16, pp. 455-460, 1981.
[27] D. Jung, K. H. Lee, D. Kim, D. Burk, L. J. Overzet, and G. S. Lee, "Highly conductive flexible multi-walled carbon nanotube sheet films for transparent touch screen," Japanese Journal of Applied Physics, vol. 52, pp. 03BC03-1-03BC03-7, 2013.
[28] D. Jung, D. Kim, K. H. Lee, L. J. Overzet, and G. S. Lee , "Transparent film heaters using multi-walled carbon nanotube sheets," Sensors and Actuators A: Physical, vol. 199, pp. 176-180, 2013.
[29] N. Behabtu, C. C. Young, D. E. Tsentalovich, O. Kleinerman, X. Wang, A. W. K. Ma et al., "Strong, Light, Multifunctional fibers of carbon nanotubes with ultrahigh conductivity," Science, vol. 339, pp. 182-186, 2020.
[30] Q. Jiang, X. Wang, Y. Zhu, D. Hui, and Y. Qiu, "Mechanical, electrical and thermal properties of aligned carbon nanotube/polyimide composites," Composites: Part B, vol. 56, pp. 408-412, 2014.
[31] K. Behler, S. Osswald, H. Ye, S. Dimovski and Y. Gogotsi, "Effect of thermal treatment on the structure of multi-walled carbon nanotubes," Journal of Nanoparticle Research, vol. 8, pp. 615-625, 2006.
[32] A. Mahajan, A. Kingon, A. Kukovecz, Z. Konya, and P. M. Vilarinho, "Studies on the thermal decomposition of multiwall carbon nanotubes under different atmospheres," Materials Letters, vol. 90, pp. 165-168, 2013.
[33] J. J. Contreras-Navarrete, F. G. Granados-Martinez, L. Domratcheva-Lvova, N. Flores-Ramirez, M. R. Cisneros-Magana, L. García-González et al., "MWCNTs oxidation by thermal treatment with air conditions," Superficies y vacio, vol. 28, no. 4, pp. 111-114. 2015.
[34] Y. Ando, X. Zhao, T. Sugai, and M. Kumar, "Growing carbon nanotubes," Mateials, vol.7, no.10, pp. 22-29, 2004.
[35] P. Nikolaev, "Catalytic growth of single-walled nanotubes by laser vaporization," Masters Thesis of Rice university, 1996.
[36] P. V. Kamat, K. G. Thomas, S. Barazzouk, G. Girishkumar, K. Vinodgopal, and D. Meisel, "Self-assembled linear bundles of single wall carbon nanotubes and their alignment and deposition as a film in a dc filed," Journal of the American Chemical Society, vol. 126, pp. 10757-10762, 2004.
[37] M. C. Lemieux, M. Roberts, S. Barman, Y. W. Jin, J. M. Kim, and Z. Bao, "Self-sorted, Aligned nanotube networks for thin-film transistors," Science, vol. 321, pp. 101-104, 2008.
[38] C. Wang, J. Zhang, K. Ryu, A. Badmaev, L. G. Arco, and C. Zhou, "Wafer-scale fabrication of separated carbon nanotube thin-film transistors for display applications," Nano Letters, vol. 9, no. 12, pp. 4285-4291, 2009.
[39] A. Schindler, J. Brill, N. Fruehauf, J. P. Novak, and Z. Yaniv, "Solution-deposited carbon nanotube layers for flexible display applications," Physica E, vol. 37, pp. 119-123, 2007.
[40] W. L. Tsai, Y. S. Chien, P. Y. Yang, I. C. Lee, K. Y. Wang, and H. C. Cheng, "Laser-unzipped carbon nanotube based glucose sensor for separated structure of enzyme modified field effect transistor," Sensor and Actuators A: Physical, vol. 204, pp. 31-36, 2013.
[41] A. Abdellah, A. Abdelhalim, F. Loghin, P. Kohler, Z. Ahmad, G. Scarpa et al., "Flexible carbon nanotube based gas sensors fabricated by large-scale spray deposition," IEEE Sensors Journal, vol. 13, pp. 4014-4021, 2013.
[42] M. Jeong, K. Lee, E. Choi, A. Kim, and S. B. Lee, "Spray-coated carbon nanotube thin film transistors with striped transport channels," Nanotechnology, vol. 23, pp. 505203-505208, 2012.
[43] K. Zhou, Z. Zhao, L. Pan, and Z. Wang, "Silicon nanowire pH sensors fabricated with CMOS compatible sidewall mask technology," Sensors and Actuators B: Chemical, vol. 279, pp. 111-121, 2019.
[44] P. K. Singh, R. Kumar, M. Lal, S. N. Singh, and B. K. Das, "Effectiveness of anisotropic etching of silicon in aqueous alkaline solutions," Solar Energy Materials & Solar Cells, vol. 70, pp. 103-113, 2001.
[45] C. Y. Kuo, S. Y Wang, S. J. Wang, R. M. Ko, Y. S. Chang, and P. T Chen, "A dual surface roughening scheme to improve the sensitivity of pH sensors based on hydrothermally grown nickel oxide nanosheets on KOH-etched Si substrates," Japanese Journal of Applied Physics, vol. 59, pp. SGGG03-1-SGGG03-9, 2020.
[46] E. J. Guidelli, E. M. Guerra, and M. Mulato, "V2O5/WO3 mixed oxide films as pH-EGFET sensor: sequential re-usage and fabrication volume analysis," ECS Journal of Solid State Science and Technology, vol. 1, no. 3, pp. 39-44, 2012.
[47] B. Xu and W. D. Zhang, "Modification of vertically aligned carbon nanotubes with RuO2 for a solid-state pH sensor," Electrochimica Acta, vol. 55, pp. 2859-2864, 2010.
[48] W. D. Zhang and B. Xu, "A solid-state pH sensor based on WO3-modified vertically aligned multiwalled carbon nanotubes," Electrochemistry Communications, vol. 11, pp. 1038-1041, 2009.
[49] S. C. Hung, N. J. Cheng, C. F. Yang, and Y. P. Lo, "Investigation of extended-gate field-effect transistor pH sensors based on different-temperature annealed bi-layer MWCNT-In2O3 films," Nanoscale Research Letters, vol. 9, pp. 502-510, 2014.
[50] P. Bergveld, "Development of an ion-sensitive solid-state device for neurophysiological measurements," IEEE Transactions on Biomedical Engineering, vol. BME-17, pp. 70-71, 1970.
[51] C. D. Fung, P. W. Cheung, and W. H. Ko, "A generalized theory of an electrolyte-insulator-semiconductor field-effect transistor," IEEE Transactions on Electron Devices, vol. 33, no. 1, pp. 8-18, 1986.
[52] P. Bergveld, "ISFET, theory and practice," in IEEE Sensor Conference, Toronto, Ontario, pp. 1-26, 2003.
[53] D. E. Yates, S. Levine, and T. W. Healy, "Site-binding model of the electrical double layer at the oxide/water interface," Journal of the Chemical Society, Faraday Transactions 1: Physical Chemistry in Condensed Phases, vol. 70, pp. 1807-1818, 1974.
[54] R. Hunter and H. Wright, "The dependence of electrokinetic potential on concentration of electrolyte," Journal of Colloid and Interface Science, vol. 37, no. 3, pp. 564-580, 1971.
[55] WiKipedia, definition-Point of zero charge, Available: https://en.wikipedia.org/wiki/Point_of_zero_charge
[56] H.-K. Liao, L.-L. Chi, J.-C. Chou, W.-Y. Chung, T.-P. Sun, and S.-K. Hsiung, "Study on pHpzc and surface potential of tin oxide gate ISFET," Materials chemistry and physics, vol. 59, no. 1, pp. 6-11, 1999.
[57] J. R. Siqueira, E. G. R. Fernandes, O. N. de Oliveira, and V. Zucolotto, "Biosensors Based on Field-Effect Devices," F. N. Crespilho (Ed.), Nanobioelectrochemistry: From Implantable Biosensors to Green Power Generation, Springer, Berlin Heidelberg, pp. 67-86, 2013.
[58] J.-L. Chang, J.-C. Chou, and Y.-C. Chen, "Study of the pH-ISFET and EnFET for biosensor applications," Journal of Medical and Biological Engineering, vol. 21, no. 3, pp. 135-146, 2001.
[59] L.-T. Yin, J.-C. Chou, W.-Y. Chung, T.-P. Sun, and S.-K. Hsiung, "Study of indium tin oxide thin film for separative extended gate ISFET," Materials Chemistry and Physics, vol. 70, no. 1, pp. 12-16, 2001.
[60] L.-L. Chi, J.-C. Chou, W.-Y. Chung, T.-P. Sun, and S.-K. Hsiung, "Study on extended gate field effect transistor with tin oxide sensing membrane," Materials Chemistry and Physics, vol. 63, no. 1, pp. 19-23, 2000.
[61] S. M. Sze and G. Y. Chang, ULSI Technology, McGraw-Hill, New York, 1996.
[62] M. Elwenspoeak, "The form of etch rate minima in wet chemical anisotropic etching of silicon," IOP Science, vol. 6, pp. 405-409, 1996.
[63] G. T. A. Kovacs, "Bulk Micromachining of silicon," Proceedings of the IEEE, vol. 86, no. 8, pp. 1536-1551, 1998.
[64] B. D. Cullity, “Element of X-ray Diffraction,” (2nd ed.), Addison-Wesley Publishing Co, MA, USA, 1978.
[65] S. M. Sze and K. K. Ng, Physics of semiconductor devices. John wiley & sons, Inc., Hoboken, New Jersey, Canada, 2006.
[66] H. Seidel, L. Csepregi, A. Heuberger, and H. Baumgärtel, "Anisotropic etching of crystalline silicon in alkaline solutions I. Orientation dependence and behavior of passivation layers," Journal of the electrochemical society, vol. 137, no. 11, pp. 3612-3626, 1990.
[67] H. Seidel, L. Csepregi, A. Heuberger, and H. Baumgärtel, "Anisotropic etching of crystalline silicon in alkaline solutions II. Influence of dopants," Journal of the Electrochemical Society, vol. 137, no. 11, pp. 3626-3632, 1990.
[68] M. Elwenspoek, "On the mechanism of anisotropic etching of silicon," Journal of the Electrochemical Society, vol. 140, no. 7, pp. 2075-2080, 1993.
[69] M. J. Madou, “Fundamentals of microfabrication: the science of miniaturization,” CRC press, USA, 2002.
[70] K. E. Bean, "Anisotropic etching of silicon," IEEE Transactions on electron devices, vol. 25, no. 10, pp. 1185-1193, 1978.
[71] I. Zubel and M. Kramkowska, "The effect of isopropyl alcohol on etching rate and roughness of (100) Si surface etched in KOH and TMAH solutions," Sensors and Actuators A: Physical, vol. 93, no. 2, pp. 138-147, 2001.
[72] D. Muñoz, P. Carreras, J.Escarré, D. lbarz, S. Martín de Nicolás, C.Voz et al., "Optimization of KOH etching process to obtain textured substrates suitable for heterojunction solar cells fabricated by HWCVD," Thin Solid Films, vol. 517, no. 12, pp. 3578-3580, 2009.
[73] I. Zubel, "The influence of atomic configuration of (hkl) planes on adsorption processes associated with anisotropic etching of silicon," Sensors and Actuators A: Physical, vol. 94, pp. 76-86, 2001.
[74] H. Mackel, H. Holst, M. Lohmann, E. Wefringhaus, and P. P. Altermatt, "Detailed analysis of random pyramid surfaces with ray tracing and image processing," IEEE J. Photovoltaics, vol. 6, pp. 1456-1465, 2016.
[75] S. Manzoor, M. Filipic, M. Topic, and Z. Holman, "Revisiting light trapping in silicon solar cells with random pyramids, "IEEE, in 2016 IEEE 43rd Photovoltaic Specialists Conference, pp. 2952-2954, 2016.
[76] Y. G. Han, X. G. Yu, D. Wang, and D. R. Yang, "Formation of various pyramidal structures on monocrystalline silicon surface and their influence on the solar cells," Journal of Nanomater, vol. 2013, pp. 716012-1-716012-5, 2013.
[77] I. Barycka and I. Zubel, "Silicon anisotropic etching in KOH-isopropanol etchant," ‎ Sensor and Actuators A, vol. 48, pp. 229–238, 1995.
[78] H. Schröder and E. Obermeier, "A new model for Si{100} convex corner undercutting in anisotropic KOH etching," Journal of Micromechanics and Microengineering, vol. 10, pp. 163-170, 2000.
[79] J. D. Hylton, A. R. Burgers, and W. C. Sinke, "Light trapping in alkaline texture etched crystalline silicon wafers," Proceedings 16th European Photovoltaic Solar Energy Conference, pp. 1434-1437, 2000.
[80] E. Wefringhaus, C. Kesnar, and M. Löhmann, "Statistical approach to the description of random pyramid surfaces using 3D surface profiles," Energy Procedia, vol. 8, pp. 135-140, 2011
[81] J. Wang and David Y. H. Pui, "Dispersion and filtration of carbon nanotubes (CNTs) and measurement of nanoparticle agglomerates in diesel exhaust," Chemical Engineering Science, vol. 85, pp. 69-76, 2013.
[82] H. Ago, T. Kugler, F. Cacialli, W. R. Salaneck, M. S. P. Shaffer, A. H. Windle, and R. H. Friend, "Work functions and surface functional groups of multiwall carbon nanotubes," Journal of Physical Chemistry B, vol. 103, pp. 8116-8121, 1999.
[83] V. Datsyuk, C. Guerret-Piecourt, S. Dagreou, L. Billon, J. C. Dupin, E. Flahaut et al., "Double walled carbon nanotube/polymer composites via in-situ nitroxide mediated polymerisation of amphiphilic block copolymers," Carbon, vol. 43, no. 4, pp. 855-894, 2005.
[84] N. Zhang, J. Xie, and V. KVaradan, "Functionalization of carbon nanotubes by potassium permanganate assisted with phase transfer catalyst," Smart Materials and Structures, vol. 11, pp. 962-965, 2002.
[85] T. I. T. Okpalugo, P. Papakonstantinou, H. Murphy, J. Mclaughlin, and N. M. D. Brown, "High resolution XPS characterization of chemical functionalized MWCNTs and SWCNTs," Carbon, vol. 43, pp. 153-161, 2005.
[86] Y. S. Park, Y. C. Choi, K. S. Kim, and D. C. Chung, "High yield purification of multiwalled carbon nanotubes by selective oxidation during thermal annealing," Carbon, vol. 39, no. 5, pp. 655- 661, 2001.
[87] W. S. Bacsa, D. Ugarte, A. Chatelain, and W. A. de Heer, "High-resolution electron microscopy and inelastic light scattering of purified multishelled carbon nanotubes," Physical Review B, vol. 50, no. 20, pp. 15473-15475, 1994.
[88] P. C. Eklund, J. M. Holden, and R. A. Jishi, "Vibrational modes of carbon nanotubes; spectroscopy and theory," Carbon, vol. 33, no. 7, pp. 959-972, 1995.
[89] P. Delhaes, M. Couzi, M. Trinquecoste, J. Dentzer, H. Hamidou, and C. Vix-Guterl, "A comparison between raman spectroscopy and surface characterizations of multiwall carbon nanotubes," Carbon, vol. 44, pp. 3005-3013, 2006.
[90] J. G. Wiltshire, A. N. Khlobystov, L. J. Li, S. G. Lyapin, G. A. D. Briggs, and R. J. Nicholas, "Comparative studies on acid and thermal based selective purification of HiPCO produced single-walled carbon nanotubes," Chemical Physics Letters, vol. 386, pp. 239-243, 2004.
[91] C. Li, D. Wang, T. Liang, X. Wang, J. Wu, X. Hu, and J. Liang, "Oxidation of multiwalled carbon nanotubes by air: benefits for electric double layer capacitors," Powder Technology, vol. 142, pp. 175-179, 2004.
[92] D. Adler and J. Feinleib, "Electrical and optical properties of narrow-band materials," Physical Review B, vol. 2, no. 8, pp. 3112-3134, 1970.
[93] J. Lewis, "Colloidal processing of ceramics," Journal of the American Ceramic Society, vol. 83, no. 10, pp. 2341-2359, 2000.
[94] N. Fiol and I. Villaescusa, "Determination of sorbent point zero charge: usefulness in sorption studies," Environment Chemical Letters, vol. 7, pp. 79-84, 2009.
[95] M. Hejazifar and S. Azizian, "Adsorption of cationic and anionic dyes onto the activated carbon prepared from grapevine rhytidome," Journal of Dispersion Science and Technology, vol. 33, pp. 846-853, 2012.
[96] L. Bousse, S. Mostarshed, B. V. D. Schoot, and N. D. Rooij, "Comparison of the hysteresis of Ta2O5 and Si3N4 pH-sensing insulators," Sensors and Actuators B: Chemical, vol. 17, no. 2, pp. 157-164, 1994.
[97] Y. Dun, W. Y. dong, and G. H. Wang, "Time-dependent response characteristics of pH-sensitive ISFET," Sensors and Actuators B: Chemical, vol. 3, pp. 279-285, 1991.
[98] K. Y. Wan, W. L. Tsai, P. Y. Yang, C. H. Chou, Y. R. Li, C. Y. Liao, and H. C. Cheng, "Effect of oxygen plasma treatment on horizontally aligned carbon nanotube thin film as pH-sensing membrane of extended-gate field-effect transistor," Japanese Journal of Applied Physics, vol. 54, pp. 04DL01-1-04DL01-6, 2015.
[99] Y. Qin, H. J. kwon, A. Subrahmanyam, M. M. R. Howlader, P. R. Selvaganapathy, A. Adronov et al., " Inkjet-printed bifunctional carbon nanotubes for pH sensing," Materials Letters, vol. 176, pp. 68-70, 2016.
[100] H.-H. Tseng, "Hydrothermal growth of NiO nanosheets and its applications on EGFET pH sensors," Masters Thesis of National Cheng Kung University, 2017.
[101] F. Lin, H. Y. Chang, S. H. Hsiao, H. I. Chen, and W. C. Liu, "Preparation and characterization of nickel oxide-based EGFET pH sensors," in Proceedings of the 9th International Conference on Sensing Technology (ICST), Auckland, New Zealand, pp. 402-405, 2015.