本論文係利用溶膠-凝膠(Sol-gel)法備製鈦酸鉛(PbTiO3)系列離子感測薄膜於參考電極(Reference electrode)/電解質(Electrolyte)/摻雜與無摻雜PbTiO3系列薄膜/二氧化矽(SiO2)/矽晶片(p-type)/鋁(Al)結構中，利用其具有類似MOS電容之特性，置於不同的pH緩衝溶液中，進行電容-電壓(C-V) 量測以探討摻雜與無摻雜PbTiO3薄膜之感測膜表面電位(Surface potential)之特性。同時亦將完成摻雜與無摻雜之PbTiO3系列薄膜作為感測膜之ISFET元件，並進行元件之電氣特性之量測與探討，以求出元件在待測溶液中起始電位(Threshold voltage)的變化情形與感測靈敏度，進而評估其摻雜之效益與最佳化參數。此外，對於元件存在之非理想特性，諸如：響應時間(Response time)、時漂(Drift)、遲滯(Hysteresis)、溫度效應(Temperature effect)及生命期(Lifetime)等參數，亦將一併進行量測、分析與比較。
實驗結果顯示，於PbTiO3 EIS結構中，若燒結溫度400℃且厚度0.5 mm之條件下，可得pH 2-12範圍內之較佳感測度55-58 mV/pH，並得知Electrolyte/PbTiO3介面具有優良之離子吸附機構及抗強酸、鹼腐蝕之要素。再者，關於PbTiO3 gate ISFET元件作用於線性區時，可獲得pH響應度55-58 mV/pH、穩態響應時間2-4 min、時漂0.5-1 mV/h、遲滯3-5 mV及衰減率 –10 mV/pH-day；另外，當PbTiO3 gate ISFET元件作用於飽和區時，pH響應度與線性度將可藉由不同閘極電壓(VGS)進行調變(Adjustment)，例如：VGS為 1、3、5 V時，pH響應度4.2、24.8、31.3 uA/pH及相關性係數(Correlation coefficient) 0.9491、0.9995、0.9996可分別被獲得。此外，Mg2+及La3+分別被摻雜於PbTiO3感測膜中，以修飾(Modification)相關感測特性，其結果得知受體(Acceptor) Mg2+將利於pH響應度(58-59 mV/pH)、時漂(0.4 mV/h)、遲滯(1-3) mV及衰減率(–0.2 mV/pH-day)之改善。最後，一數位型pH量測儀已被設計與實現。

The sol-gel-derived lead titanate (PbTiO3) membrane has been successfully applied as a novel pH-sensing layer to form the PbTiO3 gate ISFET (ion-sensitive field-effect transistor). There exhibit the excellent quasi-Nernstian response of 55-58 mV/pH, good surface adsorption and anticorrosion characteristics via the capacitance- voltage measurement of the electrolyte-insulator-semiconductor structure. At a specific pH concentration, the output and transfer characteristics of the PbTiO3 gate ISFET are very similar to the behaviours of MOSFETs (metal-oxide-semiconductor field-effect transistors), and the pH-ISFET model can be derived by the modified MOSFET model. As it operated in the nonsaturation region, there exhibits a linear pH response of about 55-58 mV/pH. Simultaneously, there exhibit the stable response time of 2-4 minutes, the drift of 0.5-1 mV/h, the hysteresis of 3-5 mV and the reduction rate of about –10 mV/pH-day. On the other hand, as it operated in the saturation region, the pH responses and linearity can be controlled by adjusting the VGS values, e.g. the absolute pH response of 4.2, 24.8 and 31.3 uA/pH and the correlation coefficients of 0.9491, 0.9995 and 0.9996 at VGS= 1, 3 and 5 V can be obtained, respectively. Besides, the PbTiO3 gate ISFET has been modified by doping the Mg2+ and La3+ impurities into the PbTiO3 membrane. As a result, the former is a great benefit to improve the pH-sensing characteristics, which exhibits the pH response of 58-59 mV/pH, the drift of below 0.4 mV/h, the hysteresis of 1-3 mV and the reduction rate of -0.2 mV/pH-day. Finally, a digital pH meter has been successfully developed.

Chapter 1 Introduction 1
Chapter 2 Theory 5
2.1 Sol-gel method 5
2.2 Site-binding model 6
2.3 EIS structure 9
2.4 pH-ISFET model 11
Chapter 3 Experimental 14
3.1 PT-series solution 14
3.2 Preparation of MIS and EIS structures 14
3.3 ISFET fabrication process 15
3.4 Packaging 15
3.5 Material analyses 16
3.5.1 Inductively coupled plasma mass spectrometry 16
3.5.2 Differential thermal and thermogravimetric analysis 16
3.5.3 X-ray diffraction 17
3.5.4 Scanning electron microscope 17
3.6 Measurement setup 17
3.6.1 Capacitance-voltage measurement 17
3.6.2 Current-voltage measurement 17
3.6.3 Drift, hysteresis and lifetime measurement 19
Chapter 4 Results and Discussion 21
4.1 Material characterization 21
4.1.1 TGA and DTA analyses 21
4.1.2 Membrane thickness 21
4.1.3 Microstructure 22
4.1.4 Permittivity 22
4.2 EIS structure 23
4.2.1 pH response 23
4.2.2 Optimum thickness 24
4.2.3 Optimum firing temperature 26
4.2.4 Point of zero charge 26
4.3 PT gate ISFET 27
4.3.1 Output and transfer characteristics 27
4.3.2 pH response 28
4.3.3 Annealing temperature 30
4.4 Nonideal factors 31
4.4.1 Exposure time 31
4.4.2 Drift 32
4.4.3 Hysteresis 33
4.4.4 Temperature effect 34
4.4.5 Lifetime 38
4.5 Modified PT membrane 39
4.5.1 Doping content 39
4.5.2 pH response 40
4.5.3 Drift 41
4.5.4 Hysteresis 42
4.5.5 Lifetime 43
4.6 Comparison 44
4.7 pH meter 46
4.7.1 Framework 46
4.7.2 Software and system layout 47
4.7.3 Achieving and testing system 48
Chapter 5 Conclusion 50
References 53
Appendix A Source code 99
Appendix B Paper list 107
Appendix C Autobiography 110

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