隨著功率元件的需求提高，氮化鎵成為被廣泛應用的材料，因為和傳統的矽材料相比，而且氮化鎵有寬能隙、高崩潰電壓、熱穩定性佳、高峰電子速率等優點。氮化鎵和氮化鋁鎵接觸所形成的異質接面時，導致壓電極化效應及自發性極化效應的產生，使電子注入導電帶不連續所形成的三角形位能井，電子侷限在其中，形成二維電子氣，具有高電流及高電子遷移率的特性。因此能使氮化鎵應用在高功率元件上。
本論文透過MEDICI元件特性模擬軟體來做元件的設計及分析，改善傳統高電子遷移率電晶體(HEMT)的特性，得到高崩潰特性HEMT元件，藉由在增強型HEMT加上底層場板的結構，來降低漂移區中靠近閘極端的電場，能大幅增強崩潰特性，有更優異表現。

As the demand for power devices increases, gallium nitride(GaN) has become a widely used material. Compared with the traditional silicon materials, gallium nitride has wide bandgap, high breakdown voltage, good thermal stability, peak electronic velocity, and so on. When gallium nitride and aluminum gallium nitride(AlGaN) contact formed heterogeneous junction, it will induce piezoelectric polarization effect and spontaneous polarization effect. Electrons are trapped in the triangular wells formed by the discontinuous conduction band, which induces a two-dimensional electron gas (2DEG) with high current and high electron mobility characteristics. Therefore, gallium nitride can be applied to high power device.
We use MEDICI device simulation software to carry out design and analysis of HEMT device. The enhanced-mode HEMT with underlayer field-plate can greatly enhance the breakdown characteristics and has more excellent performance, by reducing the electric field near the gate edge in the drift region.

[1] M.Benny Sathish, A.S. Augustine Fletcher, “Design and modeling of HEMT using field plate technique,” International Conference on Innovations in Electrical, Electronics, Instrumentation and Media Technology (ICEEIMT), pp.157–159, February 2017.

[2] G. Xie, E. Xu, J. Lee, N. Hashemi, “Breakdown voltage enhancement for power AlGaN/GaN HEMTs with air-bridge field plate,” Proceedings of the 24th International Symposium on Power Semiconductor Devices and ICs(ISPSD), pp.337–340, June 2012.

[3] A. Chitransh, S. Moonka, A. Priya, “Analysis of breakdown voltage of a field plated high electron mobility transistor,” Devices for Integrated Circuit (DevIC), pp.167–169, March 2017.

[4] N. Kurbanova, O. Demchenko, “Field-plate design optimization for high-power GaN high electron mobility transistors,” International Siberian Conference on Control and Communications (SIBCON), pp.1–4, June 2017.

[5] T. Nanjo, A. Imai, Y. Suzuki, “AlGaN channel HEMT with extremely high breakdown voltage,” IEEE transactions on electron devices, vol. 60, no. 3, pp.1046–1053, March 2013.

[6] S. Kumar, V. Kumar, A. Islam, “Characterisation of field plated high electron mobility transistor,” International Conference on Microelectronics, Computing and Communications (MicroCom), pp.1–3, January 2016.

[7] W. Saito, M. Kuraguchi, Y. Takada, “Influence of surface defect charge at AlGaN–GaN-HEMT upon schottky gate leakage current and breakdown voltage,” IEEE transactions on electron devices, vol. 52, no. 2, pp.159–164, February 2005.

[8] F. Sacconi, A. Di Carlo, P. Lugli, H. Morkoç, “Spontaneous and piezoelectric polarization effects on the output characteristics of AlGaN/GaN hetero-junction modulation doped FETs,” IEEE transactions on electron devices, vol. 48, no. 3, pp. 450–457, March 2001.

[9] G. Longobardi, F. Udrea, S. Sque, “Modelling 2DEG charges in AlGaN/GaN hetero-structures,” International Semiconductor Conference (CAS), pp.363–366, October 2012.

[10] B. Tierney, S. Choi, “Evaluation of a “Field Cage” for electric field control in GaN-based HEMTs that extends the scalability of breakdown into the kv regime,” IEEE transactions on electron devices, vol. 64, no. 9, pp.3740–3747, September 2017.

[11] U. Mishra, P. Parikh, Y. Wu, “AlGaN/GaN HEMTs—an overview of device operation and applications,” Proceedings of the IEEE, vol. 90,
no. 6, pp. 1022–1031, June 2002.

[12] W. Fu, B. Yan, Y. Xu, Y. Guo, “Simulation of microwave power characteristics of AlGaN/AlN/GaN HEMT,” 2nd International Conference on Consumer Electronics, Communications and Networks (CECNet), pp.564–566, April 2012.

[13] Y. Pei, R. Chu, L. Shen, N. Fichtenbaum, “Effect of Al composition
and Gate recess on power performance of AlGaN/GaN high-electron mobility transistors,” IEEE electron device letters, vol. 29, no. 4,
pp.300–302, April 2008.

[14] W. Saito, T. Nitta, Y. Kakiuchi, “Suppression of dynamic on-resistance increase and Gate charge measurements in high-voltage GaN-HEMTs with optimized field-plate structure,” IEEE transactions on electron devices,
vol. 54, no. 8, pp.1825–1830, August 2007.

[15] W. Huang, S. Zhang, J. Xu, “High-breakdown voltage field-plated normally-off AlGaN/GaN HEMTs for power management,” 10th IEEE international conference on solid-state and integrated circuit technology, pp.1335 – 1337, November 2010.

[16] H. Onodera, K. Horio, “Physics-based simulation of field-plate effects on breakdown characteristics in AlGaN/GaN HEMTs,” Proceedings of the 7th European Microwave Integrated Circuits Conference (EUMIC), pp.401 – 404, October 2012.

[17] G. Xie, B. Zhang, F. Fu, “Breakdown voltage enhancement for GaN high electron mobility transistors,” Proceedings of the 22nd International Symposium on Power Semiconductor Devices and ICs (ISPSD),
pp.237 – 240, June 2010.

[18] T. Asano, N. Yamada, T. Saito, “Breakdown characteristics in AlGaN/GaN HEMTs with multi-field-plate structure,” IEEE International Meeting for Future of Electron Devices, Kansai (IMFEDK), pp.1 – 2, May 2012.

[19] Y. Ando, W. Contrata, N. Samoto, “Gate length scaling for Al Ga N/GaN HJFETs: Two-dimensional full band Monte Carlo simulation including polarization effect,” IEEE trans. electron devices, vol. 47, no. 11, pp. 1965–1972, November 2000.

[20] C. Suh, Y. Dora, N. Fichtenbaum, “High-breakdown enhancement-mode AlGaN/GaN HEMTs with integrated slant field-plate,” International
Electron Devices Meeting (IEDM), pp.1 – 3, December 2006.

[21] K. Cen, Z. Jianjun, K. Yuechan, “Enhancement-mode GaN HEMT power electronic device with low specific on resistance,” 14th China International Solid State Lighting: International Forum on Wide Bandgap Semiconductors China (SSLChina: IFWS), pp.183 – 185, November 2017.

[22] H. Chiu, Y. Chang, B. Li, “High-performance normally off p-GaN gate HEMT with composite AlN/Al_0.17 Ga_0.83 〖N/Al〗_0.3 Ga_0.7 N barrier layers design,” IEEE journal of the electron devices society, vol. 6,
pp.201 – 206, January 2018.