本論文主要探討伽瑪射線和中子輻射對碳化矽元件的影響，伽瑪射線會對半導體材料造成游離效應，中子輻射則對半導體材料造成位移損傷破壞晶格結構。
碳化矽材料有好的抗輻射能力，但元件不一定有好的抗輻射能力，論文中會使用蕭基二極體、金氧半電晶體和電容器等等來進行量測，以觀察元件的變化。觀察到伽瑪射線會在碳化矽跟氧化層的介面處引進氧化層捕捉電荷改變其閾值電壓，且使介面陷阱密度提升。中子輻射則是對元件造成整體的位移損傷，在中子通量為5×1014n/cm2時，會使n type飄移區補償了2.75×1015cm-3到3.91×1015 cm-3濃度，造成飄移區濃度較淡的元件帶來災難性的損壞，且透過深能阱暫態能譜觀察到飄移區有缺陷的存在。
碳化矽元件應調整閾值電壓的數值及設計較薄的氧化層使元件對伽瑪射線有抵抗力。碳化矽元件應把濃度較淡的區域調高其濃度來抵抗中子輻射。

This thesis investigates the effects of gamma ray and neutron radiation in 4H-SiC devices. It is commonly accepted that gamma ray leads to ionization effect, and neutron radiation causes displacement damage to destroy the crystal structure on semiconductor material.
Even though silicon carbide has good radiation resistance, but devices might suffer from different mechanisms can behave differently. In this study we measure 4H-SiC Schottky diodes, MOSFETs and capacitors to investigate their variation. It is observed that gamma ray introduces oxide trapped charge at the SiC/SiO2 interface to change the threshold voltage and increase the density of interface traps. Neutron radiation brings the overall displacement damages to the bulk of the devices. When the neutron flux is 5×1014 n/cm2, 2.75×1015cm-3 to 3.91×1015cm-3 of the doping concentration in the n-type drift layer is compensated and causes catastrophic damage to the devices. The defects in the drift region has also been observed by deep level transient spectroscopy.
It is recommended that 4H-SiC devices should adjust the threshold voltage value and consist a thin gate oxide layer to be gamma ray resistant. 4H-SiC devices should increase the doping concentration in order to be robust against the neutron irradiation

[1] J. A. Cooper, M. R. Melloch, R. Singh, A. Agarwal, J. W. Palmour, “Status and prospects for SiC power MOSFETs,” IEEE Transactions on Electron Devices, vol. 49, no. 4, pp. 658–664, August 2002.

[2] B. J. Baliga, Silicon Carbide Power Devices, World Scientific Publishing Co. Pte. Ltd. 2005.

[3] C. Claeys, E. Simoen, Radiation Effects in Advanced Semiconductor Materials and Devices, Springer-Verlag Berlin Heidelberg, 2002.

[4] J.F. Ziegler, “Terrestrial Cosmic Rays”, IBM Journal of Research and Development, Vol. 40, no. 1, pp.19-39, January 1996.

[5] J. M. McGarrity, F. B. McLean, W.M. DeLancey, J. Palmour, C. Carter, J. Edmond, R.E. Oakley, “Silicon Carbide JFET Radiation Response,” IEEE Transactions on Nuclear Science, vol. 39, no. 6, pp. 1974-1981, December 1992.

[6] D.C. Sheridan, G. Chung, S. Clark, J.D. Cressler, “The Effects of High-Dose Gamma Irradiation on High-Voltage 4H-SiC Schottky Diodes and the SiC-SiO2 Interface,” IEEE Transactions on Nuclear Science, vol. 48, no. 6, pp. 2229-2232, December 2001.

[7] A. Akturk, J. M. McGarrity, S. Potbhare, N. Goldsman, “Radiation Effects in Commercial 1200 V 24 A Silicon Carbide Power MOSFETs,” IEEE Transactions on Nuclear Science, vol. 59, no. 6, pp. 3258-3264, December 2012.

[8] R.A. Wullaert, J.F. Kircher, R.E. Bowman, Effects of Radiation on Materials and Components, Reinhold Publishing Corp, 1964.

[9] G. Davydov, V. Luchinin, A. Nikiforov, “Effect of Irradiation with Fast Neutrons on Electrical Characteristics of Devices Based on CVD 4H-SiC Epitaxial Layers,” Semiconductors, vol. 37, no. 10, pp. 1229-1233, October 2003.
[10] K. Rashed, R. Wilkins, A. Akturk, R. C. Dwivedi, B. B. Gersey, “Terrestrial Neutron Induced Failure in Silicon Carbide Power MOSFETs,” IEEE Radiation Effects Data Workshop, July 2014.

[11] M. C. Tarplee, V. P. Madangarli, and Q. Zhang, “Design rules for field plate edge termination in SiC Schottky diodes,” IEEE Transactions on Electron Devices, vol. 48, no. 12, pp. 2659-2664, Dec. 2001.

[12] K. Ueno, T. Urushidani ; K. Hashimoto ; Y. Seki, “The guard-ring termination for the high-voltage SiC Schottky barrier diodes,” IEEE Electron Device Letters, vol. 16, no. 7, pp. 331-332, July 1995.

[13] T. Hiyoshi, T. Hori, J. Suda, T. Kimoto, “Simulation and experimental study on the junction termination structure for high-voltage 4H-SiC PiN diodes,” IEEE Transactions on Electron Devices, vol. 55, no. 8, pp. 1841–1846, July 2008.

[14] S. Harada, M. Kato, T. Kojima, K. Ariyoshi, Y. Tanaka, H. Okumura, “Determination of optimum structure of 4H-SiC Trench MOSFET,” 24th International Symposium on Power Semiconductor Devices and ICs, June 2012.

[15] A. Akturk, R. Wilkins, J. McGarrity, “Terrestrial Neutron Induced Failures in Commercial SiC Power MOSFETs at 27℃ and 150℃,” IEEE Radiation Effects Data Workshop, July 2005.

[16] D. Lang, “Deep‐ level transient spectroscopy: A new method to characterize traps in semiconductors,” Journal of Applied Physics, vol. 45, p. 3023, 1974.

[17] U. S. Qurashi, “study of defect characteristics in some technologically important compound semiconductors,” Quaid-i-Azam University, Islamabad, pp.56-57, Jane 1996.

[18] H. F. Li, S. Dimitrijev, D. Sweatman, and H. B. Harrison, “Effect of NO annealing conditions on electrical characteristics of n-type 4H-SiC MOS capacitors,” Journal of Electronic Materials, vol. 29, p. 1027-1032, January 2000
[19] J. Rozen, S. Dhar, M. E. Zvanut, J. R. Williams, L. C. Feldman, “Density of interface states, electron traps, and hole traps as a function
of the nitrogen density in SiO2 on SiC,” Journal of Applied Physics, vol. 105, no. 12, June 2009.

[20] J. R. Schwank, M. R. Shaneyfelt, D. M. Fleetwood, J. A. Felix, P. E.
Dodd, P. Paillet, V. Ferlet-Cavrois, “Radiation effects in MOS oxides,” IEEE Transactions on Nuclear Science, vol. 55, no. 4, pp. 1833-1853, August 2008.

[21] C. X. Zhang, E. X. Zhang, D. M. Fleetwood, R. D. Schrimpf, S. Dhar, S. H. Ryu, X. Shen, S. T. Pantelides, “Effects of Bias on the Irradiation and Annealing Responses of 4H-SiC MOS Devices,” IEEE Transactions on Nuclear Science, vol. 58, no. 6, pp. 2925-2929, October 2011.

[22] E. X. Zhang, C. X. Zhang, D. M. Fleetwood, S. T. Pantelides, “Bias-temperature instabilities and radiation effects on SiC MOSFETs,” ECS Transactions, pp. 369-380, January 2011

[23] Z. Li, C. J. Li, E. Verbitskaya, V. Eremin “Temperature stimulated reverse annealing of neutron induced damage in high resistivity silicon detectors,” IEEE Nuclear Science Symposium and Medical Imaging Conference Record, October 1995

[24] H. M. Ayedh, M. Puzzanghera, B. G. Svensson, R. Nipoti “DLTS study on Al+ ion implanted and 1950°C annealed p-i-n 4H-SiC vertical diodes,” European Conference on Silicon Carbide & Related Materials, September 2016