고려대학교

목차

ABSTRACTS = 3
CONTENTS = 7
LIST OF TABLES = 12
LIST OF FIGURES = 13
NOMENCLATURE = 19
CHAPTER I. INTRODUCTION = 22
Ⅰ.1. Research trend in chemical sensors = 13
Ⅰ.2. Classification of chemical sensors and their applications = 25
Ⅰ.2.1. Oxide semiconductor gas sensor = 29
Ⅰ.2.2. FET and diode gas sensor = 30
Ⅰ.2.3. Solid electrolyte sensor = 30
Ⅰ.2.4. Ion selective electrode = 31
Ⅰ.3. Detection type of chemical sensors and their developing stages = 32
Ⅰ.3.1. Detection type = 32
Ⅰ.3.2. Developing stages = 34
Ⅰ.4. Objectives = 36
CHAPTER Ⅱ. GAS SENSING PROPERTIES OF SINTERED TIN OXIDES = 37
Ⅱ.1. Introduction = 37
Ⅱ.2. Theoretical background = 40
Ⅱ.2.1. Electronic surface states and space charge layers = 40
Ⅱ.2.2. The conductivity mechanism = 45
Ⅱ.2.3. The behavior of massive porous bodies = 46
Ⅱ.3. Experimental = 50
Ⅱ.3.1. Experimental apparatus = 50
Ⅱ.3.2. Preparation of tin oxide powder and sensor elements = 50
Ⅱ.3.3. TPD(temperature programmed desorption) measurement = 53
Ⅱ.3.4. Measurement of gas sensing properties = 54
Ⅱ.4. Results and discussion = 56
Ⅱ.4.1. Crystal structure and morphology = 56
Ⅱ.4.2. Oxygen-desorption phenomena = 59
Ⅱ.4.3. Specific surface area = 61
Ⅱ.4.4. Gas sensitivities with the variation of sensor temperature = 61
Ⅱ.4.5. Sintering effect on the gas sensitivities = 65
Ⅱ.4.6. Relationship between the gas sensitivities and Pd-catalyst = 68
Ⅱ.4.7. Gas concentration effect on the sensor resistance ratio = 70
Ⅱ.5. Conclusions = 72
CHAPTER Ⅲ. EFFECT OF HEAT TREATMENT ON STRUCTURAL, ELECTRICAL AND GAS SENSING PROPERTIES OF ELECTRONBEAM EVAPORATED TIN OXIDE FILMS = 73
Ⅲ.1. Introduction = 73
Ⅲ.2. Theoretical background = 75
Ⅲ.2.1. Measurements of mobility and resistivity = 75
Ⅲ.2.2. Structural, electrical, and optical properties of SnO₂ = 80
Ⅲ.2.3. Gas sensing mechanisms in SnO₂ thin films = 82
Ⅲ.2.4. Gas sensing models in SnO₂ thin films = 87
Ⅲ.2.5. Effect of noble metal catalysts on the gas sensing properties of SnO₂ thin films = 95
Ⅲ.3. Experimental = 99
Ⅲ.3.1. Experimental apparatus = 99
Ⅲ.3.2. Preparation of tin oxide thin films type sensors = 101
Ⅲ.3.3. Annealing effect on the structure of SnO₂ thin films = 101
Ⅲ.3.4. measurement of Hall Effect and sheet resistance = 103
Ⅲ.3.5. Measurement of optical properties = 106
Ⅲ.3.6. Measurement of gas sensing proerties = 107
Ⅲ-4. Results and discussion = 109
Ⅲ-4-1. Crystal structure changes by annealing treatment = 109
Ⅲ-4-1-1. Effect of the isothermal heat treatment = 109
Ⅲ-4-l-2. Effect of the isochronal heat treatment = 112
Ⅲ-4-1-3. Heat treatment effect on the surface micro-structure = 114
Ⅲ-4-2. Heat treatment effect on the electrical properties = 118
Ⅲ-4-2-1. Effect of the isothermal heat treatment on the sheet resistance = 118
Ⅲ-4-2-2. Effect of the isochronal heat treatment on the sheet resistance = 120
Ⅲ-4-2-3. Measurement of Hall effect = 120
Ⅲ-4-3. Optical properties = 125
Ⅲ-4-3-1. Optical transmission = 125
Ⅲ-4-3-2. Absorption coefficient and energy band gap = 127
Ⅲ-4-4. Gas sensing properties = 130
Ⅲ-4-4-1. Effect of annealing temperature on gas sensing properties = 130
Ⅲ-4-4-2. Effect of noble metal catalysts on gas sensing properties = 136
Ⅲ-4-4-3. Relationship between the electrical properties and the gas concentration = 148
Ⅲ-4-4-4. Analogical inferences from SnO₂ thin film type sensor parameters and its surface potential = 156
Ⅲ-5. Conclusions = 158
CHAPTER Ⅳ.GAS SENSING PROPERTIES OF DIODE TYPE SENSORS = 160
Ⅳ-1. Introduction = 160
Ⅳ-2. Theoretical background = 162
Ⅳ-3. Experimental = 166
Ⅳ-3-1. Experimental apparatus = 166
Ⅳ-3-2. Sample characteristics = 168
Ⅳ-3-3. Oxide growth by thermal oxidation = 168
Ⅳ-3-4. Device fabrication = 169
Ⅳ-3-5. I-V characteristics of diode type sensors in air with and without hydrogen = 171
Ⅳ-4. Results and discussion = 175
Ⅳ-4-1. I-V characteristics of Pd-MIS diode with various hydrogen concentration = 175
Ⅳ-4-2. Differences of current ratio between HPS 2.1 and HPS 2.2 = 178
Ⅳ-4-3. Comparison the data with theoretical analysis in Pd-MIS diode = 178
Ⅳ-4-4. Detection methods of Au-SnO₂ diode sensors in hydrogen sensing at room temperature = 183
Ⅳ-4-5. Gas sensing properties of Au-SnO₂ diode sensors = 188
Ⅳ-4-6. I-V characteristics of Au-SnO₂ diode sensors = 195
Ⅳ-4-7. Barrier height changes according to the type of semiconductor = 198
Ⅳ-5. Conclusions = 202
CHAPTER V. STRUCTURE AND OXYGEN SENSING PROPERTIES OF LaF₃ THIN FILMS AND FET DEPOSITED BY RF-MAGNETRON SPUTTERING = 204
Ⅴ.1. Introduction = 203
Ⅴ.2. Theoretical background = 204
Ⅴ.3. Experimental = 207
Ⅴ.3.1. Experimental apparatus = 207
Ⅴ.3.2. Fabrication process of thin film type sensors = 208
Ⅴ.3.3. Fabrication process of Pd/LaF₃/Sn, SnF₂/SiO₂/p-Si FET = 210
Ⅴ.3.4. Lithography = 210
Ⅴ.3.5. Measurement of oxygen sensing properties = 215
Ⅴ.4. Results and discussion = 217
Ⅴ.4.1. Crystal structure of LaF₃ film = 217
Ⅴ.4.2. Oxygen sensing properties of a LaF₃ thin film type sensor = 217
Ⅴ.4.3. Lifetime of a LaF₃ thin film type sensor = 220
Ⅴ.4.4. Oxygen sensing mechanism of Laf₃ thin film type sensor = 224
Ⅴ.4.5. Effect of pH on the EMF of a Laf₃ thin film type sensor = 227
Ⅴ.4.6. Oxygen sensing properties of MIS-FET type sensor = 229
Ⅴ.5. Conclusions = 234
REVIEW OF CONCLUSIONS = 235
REFERENCES = 237
APPENDICES = 245
KOREAN ABSTRACTS = 253
CURRICULUM VITAE = 257
ACKNOWLEDGEMENT = 262