在本論文中，我們研究高穩定性的凹槽閘極之氮化鋁銦/氮化鎵金屬-絕緣體-半導體(金絕半)高電子遷移率電晶體。
首先，我們採用了凹槽閘極結構的設計，於閘極下方透過部分蝕刻，從而實現增強式元件。且因閘極下方部分蝕刻，閘極金屬距離二維電子氣通道更近，能夠有效地提高閘極的控制能力。
為了追求元件的高穩定性，我們使用氮化矽當作鈍化層，可以減少表面缺陷，有效抑制在電晶體表面的電流崩潰。而在閘極介電層的部分，則是採用氧化鋁加氮化矽的雙層結構，在氧化鋁下方添加一層薄薄的氮化矽，能夠修補電晶體表面的氮缺陷，且因氮化矽很薄，能夠降低氮化矽本身低介電常數的影響，使雙層閘極介電層仍具有高介電常數，有良好的閘極控制能力。閘極下方因不同厚度的氮化矽形成場板，達到分散電場的作用，並且上述所提到的氮化矽鈍化層能夠減少表面缺陷，因此元件能夠有效地提高崩潰電壓。
在本論文中，為了研究雙層閘極介電層的化學元素組成、表面特性、厚度，進行了一系列的材料分析。例如：X射線光電子能譜、X射線繞射、原子力顯微鏡、穿透式電子顯微鏡。為了探討元件穩定性，也進行了一系列的量測分析，例如：磁滯曲線、電流崩潰、低頻雜訊。該元件的臨界電壓為0.8 V，開關電流比為3.35×10^9，次臨界擺幅為89 mV/decade，最大汲極電流為388 mA / mm，崩潰電壓為330 V，與傳統的增強式元件相比，所有的特性都得到了改善。

In this work, we demonstrate a high stability recessed-gate InAlN/GaN metal-insulator-semiconductor high electron mobility transistors (MISHEMTs).
First, we exploit a recessed-gate design. It was partially recessed under the gate to realize an enhancement-mode device. Moreover, due to the partial recessed-gate, the gate electrode is closer to the two-dimensional electron gas channel, which can effectively improve the control ability of the gate.
To pursue the high stability of the device, we use SiN as a passivation layer, which can reduce surface defects and effectively suppress the current collapse on the surface of the transistor. For the gate dielectric layer, we use Al2O3 and SiN as the dual dielectric layers. A thin film of SiN is deposited under Al2O3 to repair the nitrogen vacancies on the surface of the device. The SiN under Al2O3 is very thin, which can reduce the influence of the low dielectric constant, so that the dual dielectric layers still have a high dielectric constant and have a good control ability of the gate. A field-plate with different thicknesses of SiN is used under the gate to distribute the electric field, and the above-mentioned SiN passivation layer can reduce surface defects, so this device can effectively improve the breakdown voltage.
In this work, to study the chemical element composition, surface characteristics, and thickness of the dual dielectric layers, a series of material analyses were carried out, such as X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), atomic force microscope (AFM), and transmission electron microscope (TEM). To explore the stability of the device, a series of measurement and analyses were also carried out, such as hysteresis curve, break-down voltage, low-frequency noise. Therefore, the device exhibits excellent characteristics, including a positive threshold voltage (VTH) of 0.8 V, on-state current/off-state current (Ion/Ioff) ratio of 3.35×10^9, subthreshold swing (SS) of 89 mV/decade, the maximum drain current (ID,max) of 388 mA/mm, and the breakdown voltage (VBD) of 330 V.

[1] T. P. Chow and R. Tyagi, “Wide bandgap compound semiconductors for superior high-voltage unipolar power devices,” IEEE Trans. Electron Devices, vol. 41, no. 8, pp. 1481–1483, Aug. 1994.
[2] U. K. Mishra, P. Parikh, and Y.-F. Wu, “AlGaN/GaN HEMTs-an overview of device operation and applications,” Proc. IEEE, vol. 90, no. 6, pp. 1022–1031, Jun. 2002.
[3] 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, “Two dimensional electron gases induced by spontaneous and piezoelectric polarization in undoped and doped AlGaN/GaN heterostructures,” J. Appl. Phys., vol. 87, no. 1, pp. 334–344, Jan. 2000.
[4] R. Wang, P. Saunier, X. Xing, C. Lian, X. Gao, S. Guo, G. Snider, P. Fay, D. Jena, and H. Xing, “Gate-recessed enhancement-mode InAlN/AlN/GaN HEMTs with 1.9-A/mm drain current density and 800-mS/mm transconductance,” IEEE Electron Device Lett., vol. 31, no. 12, pp. 1383–1385, Dec. 2010.
[5] L.-Y. Su, F. Lee, and J. J. Huang, “Enhancement-mode GaN-based high-electron mobility transistors on the Si substrate with a p-type GaN cap layer,” IEEE Trans. Electron Devices, vol. 61, no. 2, pp. 460–465, Feb. 2014.
[6] Y. Cai, Y. Zhou, K. M. Lau, and K. J. Chen, “Control of threshold voltage of AlGaN/GaN HEMTs by fluoride-based plasma treatment: from depletion mode to enhancement mode,” IEEE Trans. Electron Devices, vol. 53, no. 9, pp. 2207–2215, Sep. 2006.
[7] H. Zhou, X. Lou, S. B. Kim, K. D. Chabak, R. G. Gordon, and P. D. Ye, “Enhancement-mode AlGaN/GaN fin-MOSHEMTs on Si substrate with atomic layer epitaxy MgCaO,” IEEE Electron Device Lett., vol. 38, no. 9, pp. 1294–1297, Sep. 2017.
[8] J. Kuzmik, “Power electronics on InAlN/(In) GaN: prospect for a record performance,” IEEE Electron Device Lett., vol. 22, no. 11, pp. 510–513, Nov. 2001.
[9] F. Medjdoub, J.-F. Carlin, M. Gonschorek, E. Feltin, M. A. Py, D. Ducatteau, C. Gaquiere, N. Grandjean, and E. Kohn, “Can InAlN/GaN be an alternative to high power/high temperature AlGaN/GaN devices?” IEDM Tech. Dig., pp. 1–4, Dec. 2006.
[10] J. Kuzmik, G. Pozzovivo, C. Ostermaier, G. Strasser, D. Pogany, E. Gornik, J.-F. Carlin, M. Gonschorek, E. Feltin, and N. Grandjean, “Analysis of degradation mechanisms in lattice-matched InAlN/GaN high-electron-mobility transistors,” J. Appl. Phys., vol. 106, no. 12, Dec. 2009.
[11] K.-W. Kim, S.-D. Jung, D.-S. Kim, H.-S. Kang, K.-S. Im, J.-J. Oh, J.-B. Ha, J.-K. Shin, and J.-H. Lee, “Effects of TMAH treatment on device performance of normally off Al2O3/GaN MOSFET,” IEEE Electron Device Lett., vol. 32, no. 10, pp. 1376–1378, Oct. 2011.
[12] B. Luo, J. W. Johnson, J. Kim, R. M. Mehandru, F. Ren, B. P. Gila, A. H. Onstine, C. R. Abernathy, S. J. Pearton, A. G. Baca, R. D. Briggs, R. J. Shul, C. Monier, and J. Han, “Influence of MgO and Sc2O3 passivation on AlGaN/GaN high-electron-mobility transistors,” Appl. Phys. Lett., vol. 80, no. 9, pp. 1661–1663, Mar. 2002.
[13] S. Sugiura, S. Kishimoto, T. Mizutani, M. Kuroda, T. Ueda, and T. Tanaka, “Normally-off AlGaN/GaN MOSHFETs with HfO2 gate oxide,” Phys. Stat. Sol. (c), vol. 5, no. 6, pp. 1923–1925, May 2008.
[14] S. Yagi, M. Shimizu, H. Okumura, H. Ohashi, Y. Yano, and N. Akutsu, “High breakdown voltage AlGaN/GaN metal–insulator–semiconductor high-electron-mobility transistor with TiO2/SiN gate insulator,” Jpn. J. Appl. Phys., vol. 46, no. 4S, Apr. 2007.
[15] B.-Y. Chou, H.-Y. Liu, W.-C. Hsu, C.-S. Lee, Y.-S. Wu, W.-C. Sun, S.-Y. Wei, and S.-M. Yu, “Al2O3-passivated AlGaN/GaN HEMTs by using nonvacuum ultrasonic spray pyrolysis deposition technique,” IEEE Electron Device Lett., vol. 35, no. 9, pp. 903–905, Sep. 2014.
[16] X. Qin, H. Dong, B. Brennan, A. Azacatl, J. Kim, and R. M. Wallace, “Impact of N2 and forming gas plasma exposure on the growth and interfacial characteristics of Al2O3 on AlGaN”, Appl. Phys. Lett., vol. 103, no. 22, Nov. 2013.
[17] S. Yang, Z. Tang, K.-Y. Wong, Y.-S. Lin, C. Liu, Y. Lu, S. Huang, and K. J. Chen, “High-quality interface in Al2O3/GaN/GaN/AlGaN/GaN MIS structures with in situ pre-gate plasma nitridation,” IEEE Electron Device Lett., vol. 34, no. 12, pp. 1497–1499, Dec. 2013.
[18] B. M. Green, K. K. Chu, E. M. Chumbes, J. A. Smart, J. R. Shealy, and L. F. Eastman, “The effect of surface passivation on the microwave characteristics of undoped AlGaN/GaN HEMTs,” IEEE Electron Device Lett., vol. 21, no. 6, pp. 268–270, Jun. 2000.
[19] E. H. Hall, “On a new action of the magnet on electric currents,” American Journal of Mathematics., vol. 2, no. 3, pp. 287–292, Sep. 1879.
[20] G. Binnig, C. F. Quate, and C. Gerber, “Atomic force mircoscope,” Phys. Rev. Lett., vol. 56, no. 9, pp. 930-933, Mar. 1986.
[21] E. Ruska, “The early development of electron lenses and electron microscopy,” Microsc Acta Suppl., pp. 1‐140, Nov. 1980.
[22] E. H. Nicollian and J. R. Brews, “MOS (metal oxide semiconductor) physics and technology,” New York: Wiley., 1982.
[23] S.-J. Chang and J.-G. Hwu, “Comprehensive study on negative capacitance effect observed in MOS(n) capacitors with ultrathin gate oxides,” IEEE Trans. Electron Devices, vol. 58, no. 3, pp. 684–690, Mar. 2011.
[24] Y. He, M. Mi, C. Wang, X. Zheng, M. Zhang, H. Zhang, J. Wu, L. Yang, P. Zhang, X. Ma, and Y. Hao, “Enhancement-mode AlGaN/GaN nanowire channel high electron mobility transistor with fluorine plasma treatment by ICP,” IEEE Electron Device Lett., vol. 38, no. 10, pp. 1421–1424, Oct. 2017.
[25] F. N. Hooge, T. G. M. Kleinpenning, and L. K. J. Vandamme, “Experiment studies on1/f noise,” Rep. Prog. Phys., vol. 44, no. 5, pp. 479–532, 1981.
[26] J. Sikula and M. Levinshtein, “Advanced experimental methods for noise research in nanoscale electronics devices,” Springer Science., vol. 151, 2005.
[27] R. Coffie, “Analytical field plate model for field effect transistors,” IEEE Trans. Electron Devices, vol. 61, no. 3, pp. 878–883, Mar. 2014.
[28] R. Coffie, “Slant field plate model for field-effect transistors,” IEEE Trans. Electron Devices, vol. 61, no. 8, pp. 2867–2872, Aug. 2014.
[29] J. T. Asubar, S. Kawabata, H. Tokuda, A. Yamamoto, and M. Kuzuhara, “Enhancement-mode AlGaN/GaN MIS-HEMTs with high VTH and high ID,max using recessed-structure with regrown AlGaN barrier,” IEEE Electron Device Lett., vol. 41, no. 5, pp. 693–696, May 2020.
[30] M. Blaho, D. Gregusova, S. Hascik, M. Tapajna, K. Frohlich, A. Satka, and J. Kuzmik, “Annealing, temperature, and bias-induced threshold voltage instabilities in integrated E/D-mode InAlN/GaN MOS HEMTs,” Appl. Phys. Lett., vol. 111, no. 3, Jul. 2017.
[31] S. L. Zhao, J. S. Xue, P. Zhang, B. Hou, J. Luo, X. J. Fan, J. C. Zhang, X. H. Ma, and Y. Hao, “Enhancement-mode Al2O3/InAlN/AlN/GaN metal-insulator-semiconductor high-electron-mobility transistor with enhanced breakdown voltage using fluoride-based plasma treatment,” Appl. Phys. Express, vol. 7, no. 7, Jun. 2014.
[32] Y.-P. Huang, W.-C. Hsu, H.-Y. Liu, and C.-S. Lee, “Enhancement-mode tri-gate nanowire InAlN/GaN MOSHEMT for power applications,” IEEE Electron Device Lett., vol. 40, no. 6, pp. 929–932, Jun. 2019.
[33] Y.-P. Huang, C.-C. Huang, C.-S. Lee, and W.-C. Hsu, “High-performance normally-off AlGaN/GaN fin-MISHEMT on silicon with low work function metal-source contact ledge,” IEEE Trans. Electron Devices, vol. 67, no. 12, pp. 5434–5440, Dec. 2020.