Thermoelectrical Effect in SiC for High-Temperature MEMS Sensors (eBook)

Preface 6
Acknowledgements 8
Contents 9
1 Introduction to SiC and Thermoelectrical Properties 12
1.1 Background 12
1.2 Silicon Carbide 14
1.3 Growth of SiC 15
1.4 Thermoelectrical Properties 16
1.5 High-Temperature SiC MEMS Sensors 18
References 18
2 Fundamentals of Thermoelectrical Effect in SiC 21
2.1 Thermoresistive Effect 21
2.1.1 Physical Parameters and Definitions in Semiconductors 23
2.1.2 Single-Crystalline SiC 23
2.1.3 Polycrystalline SiC 25
2.1.4 Amorphous SiC 27
2.2 Thermoelectronic Effects 27
2.3 Thermocapacitive Effect 28
2.4 Thermoelectric Effect 29
2.5 Recent Advances in Characterisation of Thermoelectrical Effects in SiC at High Temperatures 30
2.5.1 Experimental Set-up for Characterisation of Thermoelectrical Effect 30
2.5.2 Thermoresistive Effect in Single Layer of SiC 31
2.5.3 Thermoelectrical Effect in Multi-layers of SiC 39
2.6 4H-SiC p–n Junctions 41
2.7 Other Thermoelectrical Effects at High Temperatures 44
2.7.1 Thermoelectric Effect 44
2.7.2 Thermocapacitive Effect 46
References 48
3 Desirable Features for High-Temperature SiC Sensors 52
3.1 Sensitivity 52
3.2 Linearity 54
3.3 Thermal Time Response 56
3.4 Low Power Consumption 57
3.5 Stability and Other Desirable Features 58
References 59
4 Fabrication of SiC MEMS Sensors 63
4.1 Growth and Doping 63
4.1.1 Growth of SiC 63
4.1.2 Doping of SiC 65
4.2 Etching of SiC 65
4.2.1 Electrochemical Etching 67
4.2.2 Chemical Etching 67
4.2.3 Dry Etching or Reactive-Ion Etching (RIE) 68
4.3 Ohmic and Schottky Contacts to SiC 68
4.3.1 Ohmic Contact 68
4.3.2 Schottky Contact 73
4.4 Fabrication Processes of SiC MEMS Sensors 75
4.4.1 Surface Micromachining 75
4.4.2 Bulk Micromachining 76
4.4.3 Fabrication of MEMS Device with Integrated Cooling System 79
References 79
5 Impact of Design and Process on Performance of SiC Thermal Devices 83
5.1 Substrate Influence 83
5.2 Doping Influence 84
5.3 Morphologies 85
5.4 Deposition Temperature 87
5.5 Geometry and Dimension 87
References 88
6 Applications of Thermoelectrical Effect in SiC 92
6.1 Temperature Sensors, Temperature Control/Compensation and Thermal Measurement 92
6.1.1 Thermistors 93
6.1.2 p–n Junction Temperature Sensors 95
6.2 Thermal Flow Sensors 96
6.2.1 Hot-Wire and Hot-Film Flow Sensors 97
6.2.2 Calorimetric Flow Sensors 101
6.2.3 Time-of-Flight Flow Sensors 102
6.3 Convective Accelerometers and Gyroscopes 103
6.3.1 Convective Accelerometers 104
6.3.2 Convective Gyroscopes 105
6.4 Other Applications 105
6.4.1 Combustible Gas Sensors 105
6.4.2 SiC MEMS with Integrated Heating, Sensing and Microfluidic Cooling 106
References 110
7 Future Prospects of SiC Thermoelectrical Sensing Devices 114
7.1 Novel Platforms of SiC Films on Insulation Substrates 114
7.2 Integration of SiC Thermoelectrical Devices with Other Materials and Devices 116
7.3 SiC Thermal Actuators 117
7.4 Challenges and Future Developments of SiC Sensing Devices 118
References 120