氮化鎵系列的高速電子遷移率電晶體(HEMTs)被認為是下一代傑出的功率開關元件之一，由於高濃度的二維電子氣通道(2DEG)和極大的崩潰電場強度(~3.5MV/cm)。
本論文利用數值模擬的方法研究三五氮化物高速電子遷移率電晶體(HEMTs)，利用氮化鋁鎵/氮化鎵/氮化鋁鎵 形成的量子井電子阻擋層(EBL)來增強元件的崩潰電壓，我們藉由模擬軟體器件APSYS完成此一任務。
此概念是基於量子井電子阻擋層提供通道中二維電子氣優越的侷限能力，使得突破性的改善崩潰電壓和顯著地抑制溢流電子，除此之外，促進通道中二維電子氣遷移率的傳輸特性。最後，關於元件量子井電子阻擋層裡井寬和成份對於崩潰電壓的影響我們系統地去計算和討論試著找出最佳化數值。本研究中，傳統HEMT結構、量子井電子阻擋層HEMT結構崩潰電壓分別為48V、285V，而量子井電子阻擋層HEMTs最高遷移率為940 cm2/Vs。
我們驗證此論文提出新穎的量子井電子阻擋層HEMTs結構比一般傳統HEMTs擁有諸多的優點，這些發現揭示出一項大有前途方法製作出快速切換的耐壓功率元件應用。

GaN-based high-electron-mobility transistors (HEMTs) are considered to be excellent candidate due to their high sheet-carrier density in the 2-D electron gas (2-DEG) channel and large breakdown field strength (~3.5MV/cm).

In this work , we numerically study the enhancement of breakdown voltage in III-nitride HEMTs by employing the AlGaN/GaN/AlGaN quantum-well (QW) electron-blocking-layer (EBL) by using APSYS. This concept is based on the superior confinement of two dimensional electron gas (2-DEG) provided by the QW EBL, which results in a significant improvement of breakdown voltage and a remarkable suppression of overflowing electrons, and promotes the mobility of transport electron.

The dependence of thickness and composition of QW on the device breakdown is systematically evaluated and discussed in detail for the device optimization. In the present study, the breakdown voltage identified for the conventional HEMT and optimized QW EBL HEMT are 48V and 285V,respectively. Additionally, the QW EBL HEMT structure exhibits the highest electron mobility of 940 cm2/Vs .

As a result, we validate the advantages of the proposed structure over the conventional AlGaN/GaN HEMT. We conclude the AlGaN/GaN/AlGaN QW EBL as a promising way to explore the AlGaN/GaN HEMTs in high-speed power-switching applications.

[1] B.J. Baliga, "Trends in power semiconductor devices," IEEE Transactions on Electron Devices, vol. 43, pp. 1717-1731,(1996).

[2] J.M. Barker, D. K. Ferry, S. M. Goodnick, D. D. Doleske, A. Allerman, and R. J. Shul, “Effects of surface treatment on the velocity-field characteristics of AlGaN/GaN heterostructures”, Semicond. Sci. Tech. 19, pp.478-480, 2004.

[3] M. A. Khan, and M. S. Shur, “GaN-Based Devices for Electronic Applications”, Vol.33, 2004.

[4] M. A. Khan, J. N. Kuznia, A. R. Bhattarai, and D. T. Oslon, “Metal semiconductor field effect transistor based on single crystal GaN”, Appl. Phys. Lett., Vol.62, pp.1786, 1993.

[5] L. F. Eastman, V. Tilak, J. Smart, B. M. Green, and J. R. Shealy, “Undoped AlGaN/GaN HEMTs for microwave power amplifiers”, IEEE Trans. Electron Devices, Vol.48, No.3, pp.479, 2001.

[6] V. Kumar, W. Lu, F.A. Khan, R. Schwindt, A. Kuliev, G. Simin, J. Yang, M. Asif Khan, and I. Adesida, “High performance 0.25 μm gate-length AlGaN/GaN HEMTs on sapphire with transconductance of over 400 mS/mm”, Electronics Lett., Vol.38, pp.252, 2002.

[7] M. A. Khan, A. Bhattarai, J. N. Kuznia, and D. T. Olson, “High electron mobility transistor based on a GaN-AlxGa1-xN heterojunction”, Appl. Phys. Lett., Vol.63, pp.1214, 1993.

[8] S. J. Cai, R. Li, Y. L. Chen, L. Wong, W. G. Wu, S. G. Thomas ,and K. L. Wang, “High performance AlGaN/GaN HEMT with improved ohmic contact”, Electronics Lett., Vol.34, pp.2354, 1998.

[9] B.J. Baliga, “Trends in power semiconductor devices,” IEEE Trans,Electron Device, vol. 43, pp. 1717-1713, Nov. 1996.

[10] N.-Q. Zhang, B. Moran, S. P. DenBaars, U. K. Mishra, X. W. Wang, andT. P. Ma, “Effects of surface traps on breakdown voltage and switching speed of GaN power switching HEMTs,” in IEDM Tech. Dig., 2001, pp. 25.5.1–25.5.4.

[11] W. Saito, I. Omura, T. Ogura, and H. Ohashi, “Theoretical limit estimation of lateral wide band-gap semiconductor power-switching device,” Solid State Electron., vol. 48, no. 9, pp. 1555–1562, Sep. 2004.

[12] N.Q. Zhnag, S. Keller, G. Parish, S. Heilman, S.P. DenBaars and U.K. Mishra, “High breakdown GaN HEMT with overlapping gate structure,”IEEE Electron Device Lett, vol. 21, pp. 421-423, 2000.

[13] Rajabi, S., Orouji, A.A. ; Moghadam, H.A. ; Mahabadi, S.E.J. ; Fathipour, M. Signal Processing, Communication, Computing and Networking Technologies (ICSCCN), 2011 International Conference Page(s): 675 - 678 .

[14] B.J. Baliga, “Trends in power semiconductor devices,” IEEE Trans,73 Electron Device, vol. 43, pp. 1717-1713, Nov. 1996.

[15] E. Bahat-Treidel, O. Hilt, F. Brunner, J. Wurfl" and G. Trankle, "Punchthrough-voltage enhancement of A1GaN/GaN HEMTs using A1GaN double-heterojunction confinement", IEEE Trans. Electron Devices, vol. 53, no. 2, pp. 3354-3359, Dec. 2008.

[16] D. Visalli, M. V. Hove, J. Derlyun, K. Cheng, S. Degroote, M. Leys, M. Germain, and G. Borghs, Phys. Status Solidi C 6, S988 (2009).

[17] W. Liu and A. A. Balandin, J. Appl. Phys. 97, 073710 (2005).

[18] P. B. Klein, S. C. Binari, K. Ikossi, A. E. Wickenden, D. D. Koleske, and R. L. Henry, Appl. Phys. Lett. 79, 3527 (2001).

[19] Y. C. Choi, M. Pophristic, B. Peres, H.-Y. Cha, M. G. Spencer, and L. F.Eastman, Semicond. Sci. Technol. 22, 517 (2007).

[20] Y. C. Choi, M. Pophristic, H.-Y. Cha, B. Peres, M. G. Spencer, and L.F.Eastman, IEEE Trans. Electron Devices 53, 2926 (2006).

[21] Saito, W. Takada, Y. ; Kuraguchi, M. ; Tsuda, K. ; Omura, I. ; Ogura, T. ; Ohashi, H. IEEE Transactions on Electron Devices, vol. 50, no. 12,(2003).

[22] http://www.ledinside.com.tw/knowledge/20120518-21167.html.

[23] http://www.moneydj.com/kmdj/wiki/wikiviewer.aspx?keyid=2c2ef994-4cac-4cd5-8637-818a058f4730.

[24] M.S. Shur and M.A. Kahn, “Wide Band Gap Semiconductors. Good Results and Great Expections”, in the Proceedings of 23d International Symposium on GaAs and Related Compounds, St. Petersburg, Russia, Sep. 22-28, 1996, Institute Phys. Conferrence Series, No.155, Chapter 2, pp. 25-32, M.S. Shur and R. Suris, Editors, IOP Publishing, London 1997.

[25] O. Ambacher, B. Foutz, J. Smart, J. R. Shealy, N. G. Weimann, K. Chu, M. Murphy, A. J. Sierakowski, W. J. Schaff, L. F. Eastman, R. Dimitrov, A. Mitchell, and M. Stutzmann J. Appl. Phys. 87, 334 (2000).

[26] O.Ambacher et al., ”Two-dimension electron gases induced by spontaneous and piezoelectric polarization charges in N- and Ga-face AlGaN/GaN heterostructures,” Jorunal of Applied Physics, Vol 85, Num 6,(3222), 1999.

[27] B. J. Baliga, "Semiconductors for high-voltage, vertical channel FET's,"J.Appl. Phys., vol. 53, pp. 1759-64, 1982.

[28] J. P. Ibbetson, P. T. Fini, K. D. Ness, S. P. DenBars, J. S. Speck, and U.K.Mishra, "Polarization effects, surface states, and the source of
electrons inAlGaN/GaN heterostructure field effect transistors," Applied Physics Letters,vol. 77, pp. 250-2, 2000.

[29] I. P. Smorchkova, C. R. Elsass, J. P. Ibbetson, R. Vetury, B. Heying, P. Fini, E. Haus, S. P. DenBaars, J. S. Speck, and U. K. Mishra, "Polarizationinduced charge and electron mobility in AlGaN/GaN heterostructures grown by plasma-assisted molecular-beam epitaxy," Journal of Applied Physics, vol. 86, pp. 4520-4526, 1999.

[30] I. P. Smorchkova, L. Chen, T. Mates, L. Shen, S. Heikman, B. Moran, S. Keller, S. P. DenBaars, J. S. Speck, and U. K. Mishra, "AlN/GaN and (Al,Ga)N/AlN/GaN two-dimensional electron gas structures grown by plasma-assisted molecular-beam epitaxy," Journal of Applied Physics, vol. 90, pp. 5196-201, 2001.

[31] KarimS. Boutros, Energytech, pp 1-4,29-31 May,2012.

[32] M. J. Ureh, K. J. Nash, R. S. Balmer, T. Martin, E. Morvan, N.Caillas, S. L. Delage, D. Ducatteau, B. Grimbert, and J. C. De Jaeger, "Punchthrough in short-channel A1GaN/GaN HFETs", IEEE Trans. Electron Devices, vol. 53, no. 2, pp. 395-398, Feb. 2006.

[33] P. Ellrodt, W. Brockerhoff, and F. J. Tegude, "Investigation of leakage current behaviour of schottky gates on InAlAs/InGaAs/InP HFET structures by a ID model", Solid State Electron. , vol. 38, no. 10, pp. 1775-1780, Oct. 1995.

[34] S. Takamiya, M. Harayama, T. Sugimura, T. Tsuzuku, T. Taya, K. Iiyama, and S. Hashimoto, "Reverse currents of schottky gates of III-V MESFET/HEMTs: Field emission and tunnel currents", Solid State Electron., vol. 42, no. 3, pp. 447-451, Mar. 1998.

[35] http://www.digitimes.com.tw/tw/dt/n/shwnws.asp?CnlID=13&id=0000324112_T8T01Z9F2FH5ZC1DWIF6D&ct=1.

[36] S. L. Chuang and C. S. Chang. k • p method for strained wurtzite semiconductors. Phys. Rev. B, 54(4):2491–2504, July 1996.

[37] S. M. Zse. Physics of semiconductor devices. John Wiley & Sons,2nd edition,1981. ISBN 978-0-471-67324-8.

[38] Fabio Della Sala, Aldo Di Carlo, Paolo Lugli, Fabio Bernardini, Vincenzo Fiorentini,Reinhard Scholz, and Jean-Marc Jancu
"Free-carrier screening of polarization fields in wurtzite GaN/InGaN laser structures" Appl. Phys. Lett. 74, 2002 (1999).

[39] D. M. Caughey and R. E. Thomas, Proc. IEEE 55, pp. 2192–2193 (1967).

[40] K. Kunihiro, K. Kasahara, Y. Takahashi, and Y. Ohno, IEEE Electron Dev. Lett. 20, pp. 608–10 (1999).

[41] D.M. Sathaiya and S. Karmalkar, ‘‘Edge Effects on Gate Tunneling Current in HEMTs’’, IEEE Transactions on Electron Devices, vol. 54, no 10, pp. 2614-2622, Oct. 2007.

[42] Maeda N.Saitoh T, Tsubaki K, Nishida T and Kobayashi N , ‘‘Two-dimensional electron gas transport properties in AlGaN/GaN single- and double-heterostructure field effect transistors’’, Materials Science and Engineering: B, Volume 82, Number 1, 22 May 2001 , pp. 232-237.

[43] Narihiko Maeda, Tadashi Saitoh, Kotaro Tsubaki, Toshio Nishida, and Naoki Kobayashi, ‘‘Enhanced effect of polarization on electron transport properties in AlGaN/GaN double-heterostructure field-effect transistors’’, Appl. Phys. Lett. 76, 3118 (2000).