本論文中為致力於利用液相氧化法成長於砷化鎵及磷化銦鎵上，作為閘極介電層並應用於磷化銦鎵/砷化銦鎵假晶高電子移動率電晶體之研究。相較於其他的氧化系統而言，液相氧化法是一種不需要額外電壓或能量輔助、簡易、低成本及低溫成長(30-70°C)的氧化法。
本論文研製之高電子移動率電晶體其閘極面積為1×100 (μm2)。針對直流特性而言，相較於傳統高電子移動率電晶體，應用磷化銦鎵氧化層作為閘極介電層於金氧半高電子移動率電晶體上，當最大閘極操作偏壓為2V時，可得最大汲極飽和電流為126 mA/mm(提升50 %)，最大轉導為118 mS/mm(提升32 %)。正向導通電壓為1.05V，逆向崩潰電壓可達-23.65 V，而傳統高電子移動率電晶體逆向崩潰電壓僅為-7.8V，於此偏壓下，閘極漏電流有效改善1640倍。
應用砷化鎵氧化層作為閘極介電層於金氧半高電子移動率電晶體上，當最大閘極操作偏壓為2V時，可得最大汲極飽和電流為310 mA/mm(提升269 %)，最大轉導可提升至186mS/mm (提升108 %)，次臨限擺幅為106mV/decade(改善58%)。正向導通電壓為0.9V逆向崩潰電壓可達-29.3 V，閘極漏電流於閘極偏壓-7.8V時，有效改善781倍。
此外，元件閘極下方表面粗糙度將直接對元件的直流以及高頻的特性產生影響。針對直流特性而言，越粗糙的表面，將造成崩潰電壓下降，閘極漏電流上升，進而影響整個直流特性。針對高頻特性而言，越粗糙的表面，將造成閘極電阻增加。此外，閘極漏電流上升，將造成雜訊的增加。這些效應將於內文討論。
針對高頻特性而言，相較傳統假晶高電子移動率電晶體，砷化鎵氧化層金氧半高電子移動率電晶體，其截止頻率為45.7 GHz(提升27 %)，最大震盪頻率為20.3 GHz(提升81 %)，對於雜訊而言，金氧半假晶高電子移動率電晶體也有較好特性。

We demonstrate the use of native GaAs and InGaP oxides as gate insulators in the fabrication of InGaP/InGaAs pseudomorphic high electron mobility transistors (pHEMTs) that are characterized through the liquid phase oxidation (LPO) method. The liquid phase oxidation system is simple, low-cost, and near temperature (30-70℃); it also does not require the use of extra energy to form a native oxide layer in comparison with the other oxidation systems.
In this work, the high electron mobility transistors are fabricated with gate geometry 1×100 (μm)2. Compared with the conventional pHEMTs, InGaP oxide is used as the gate insulator for MOS-pHEMT applications in the DC measurements. The maximum drain current density is found to be 126 mA/mm at the gate-to-source voltage of 2 V, representing an improvement of about 50%. Meanwhile, the extrinsic transconductance is 118 mS/mm, representing an improvement of about 32%. The maximum turn-on voltage is 1.05 V, and the breakdown voltage is -23.65 V. The gate leakage current density can be improved about 1640 times at VGD=-7.8V.
GaAs oxide is used as the gate insulator for MOS-pHEMT applications. The maximum drain current density is at 310 mA/mm at the gate-to-source voltage of 2 V; this represents an improvement of about 269%. The extrinsic transconductance is 186 mS/mm, which represents an improvement of about 108%. The sub-threshold swing is 106 mV/decade, which improved by about 58%. The maximum turn-on voltage is 0.9 V, and the breakdown voltage is -29.3 V. The gate leakage current density can be improved by about 781 times at VGD=-7.8V.
The surface roughness of the gate interface influenced the DC and microwave performances. In the DC performances, the rougher surface caused a decrease in breakdown voltage and an increase in leakage current. Meanwhile, in the microwave performances, the rougher surface caused an increase in gate resistance.
The cut-off frequencies and the maximum oscillation frequencies of MOS-pHEMTs with GaAs oxide are 45.73 and 20.26 GHz, indicating an improvement of about 27% and 81%, respectively.

[1]J. Bardeen and W. H. Brattain, “The transistor, a semiconductor triode,” Phys. Rev.,vol. 74, pp. 230-231, 1948.
[2]D. Kahng and M. M. Atalla, “Silicon-silicon dioxide field induce surface devices”, IRE Solid-State Device Res. Conf., (Carnegie Institute of Technology, Pittsburgh, PA.),1960.
[3]F. Ali and A. Gupta, HEMTS and HBTS:Devices,Fabrication and Circuits, Boston London: Artech House, 1991.
[4]T. Mimura, S. Hiyamizu, T. Fujii and K. Nanbu, “A new field effect transistor with selectively doped GaAs/n-AlGaAs heterostructures,” Jpn. J. Appl. Phys., vol. 19, pp. L225-227, 1980.
[5]T. Henderson, M. Aksun, C. Peng, H. Morkoc, P.C. Chao, P.M. Smith, K.H.G. Duh, and L.F. Lester, “Microwave performance of a quarter-micrometer gate low-noise pseudomorphic InGaAs/AlGaAs MODFET,” IEEE Electron Device Lett., vol. EDL-7, pp. 645, 1986.
[6]H. L. Störmer, R. Dingle, A. C. Gossard, W. Wiegmann and M. D. Sturge,“Two dimensional electron gas at a semiconductor–semiconductor interface,” Solid-State Comm., vol. 29, pp. 705-709, 1979.
[7]D. Delagebeaudeuf, P. Delescluse, P. Etienne, M. Labnion, J. Chaplart and N.T. Linh, “Two dimensional elecron gas MESFET structure,” Electronics Letters, vol. 16, pp. 667-668, 1980.
[8]F. Schwierz and J J. Liou, Modern Microwave Transistors: Theory, Design, and Performance, USA, New Jersey, John Wiley & Sons, Inc, 2002.
[9]S. Subramanian, “Model for the temperature dependence of the threshold voltage of modulation-doped field-effect transistors,” IEEE Trans. Electron Devices, vol. 32, pp. 865-870, 1980.
[10]R. Menozzi, P. Cova, C. Canali and F.Fantini,
“Breakdown walkout in pseudormorphic HEMT’s,” IEEE Trans. Electron Dev., vol. 43, pp. 543-546, 1996.
[11]S. Fujita, T. Noda, A. Wagai, C. Noxaki and Y.Ashizawa,
“Novel HEMT structure using a strained InGaP Schottky layer,” in 5th Proc. of Indium Phosphide and Relsted Materials, pp. 497-500, 1993.
[12]H. K. Huang, C. S. Wang, Y. H. Wang, C. L. Wu and C. S. Chang, “Temperature effects of low noise InGaP/InGaAs/GaAs PHEMTs,” Solide-State Electron., vol. 47, pp. 1989-1994, 2003.
[13]Y. S. Lin, S. S. Lu and Y. J. Wang, “High-performance GaInP/GaAs airbridge gate MISFET’s grown by gas-source MBE,” IEEE Trans. Electron Dev., vol. 44, pp. 921-929, 1997.
[14]M. A. Rao, E. J. Caine, H. Kroemer, S. I. Long and D. I. Babic, “Determination of valence and conduction-band discontinuites at the (Ga,In)P/GaAs heterojunction by C-V profiling,” J. Appl. Phys., vol. 61, pp. 643-649, 1987.
[15]W. C. Liu, W. L. Chang, W. S. Lour, H. J. Pan, W. C. Wang, J. Y. Chen, K. H. Yu, and S. C. Feng, “High-performance InGaP/InxGa1-xAs HEMT with an inverted delta-doped V-shaped channel structure,” IEEE Electron Dev. Lett., vol. 20, p. 548, 1999.
[16]K. W. Lee, Y. J. Lin, N. Y. Yang, Y. C. Lee, P. W. Sze, Y. H. Wang and M. P. Houng, “InGaP/InGaAs/GaAs metal-oxide semiconductor pseudomorphic high electron mobility transistor with a liquid phase oxidized InGaP gate,” in proceedings of 7th IEEE International Conference on Solid-State and Integrated Circuits Technology (ICSICT), pp. 2301-2304, 2004.
[17]H. H. Wang, Y. H. Wang and M. P. Houng, “Near room temperature selective oxidation on GaAs using photoresist as a mask,” Jpn. J. Appl. Phys., vol. 37, pp. L988-990, 1998.
[18]H. H. Wang, Y. H. Wang and M. P. Houng, “Near room temperature selective oxidation on GaAs using photoresist as a mask,” Jpn. J. Appl. Phys., vol. 37, pp. L988-990, 1998.
[19]H. H. Wang, J. Y. Wu, Y. H. Wang and M. P. Houng, “Effect of PH values on the kinetics of liquid phase chemical enhanced oxidation of GaAs,” J. Electronchem. Soc., vol. 146, pp. 2328-2332, 1999.
[20]J. Y. Wu, H. H. Wang, Y. H. Wang and M. P. Houng, A GaAs MOSFET with a liquid phase oxidized gate,” IEEE Electron Dev. Lett., vol. 20, pp. 18-20, 1999.
[21]J. Y. Wu, H. H. Wang, Y. H. Wang and M. P. Houng, “GaAs MOSFET’s fabrication with a liquid phase oxidized gate,” IEEE Trans. Electron Dev., vol. 48, pp. 634-637, 2001.
[22]K. W. Lee, P. W. Sze, Y. H. Wang and M. P. Houng, “Liquid phase chemical enhanced oxidation on AlGaAs and its application,” Jpn. J. Appl. Phys., vol. 43, pp. 4087-4091, 2001.
[23]K. W. Lee, P. W. Sze, Y. H. Wang and M. P. Houng, “AlGaAs/InGaAs metal-oxide-semiconductor pseudomorphic high-electron–mobility transistor with a liquid phase oxidized AlGaAs as gate dielectric,” Solid-State Electron., vol. 49, pp. 213-217, 2005.
[24]K. W. Lee, K. L. Lee, H. C. Lin, C. H. Tu, C. C. Hu, and Y. H. Wang, “Near-room-temperature selective oxidation on InAlAs and application to In0.52Al0.48As/In0.53Ga0.47As metamorphic HEMTs,” J. Electrochem. Soc., vol. 154, no. 11, pp. H957-H961, 2007.
[25]K. W. Lee, N. Y. Yang, M. P. Houng and Y. H Wang, “Improved breakdown voltage and impact ionization in InAlAs/InGaAs metamorphic high-electron-mobility transistor with a liquid phase oxidized InGaAs gate,” Appl. Phys. Lett., vol. 87, pp. 263501-1-263501-3, 2005.
[26]K. W. Lee, P. W. Sze, Y. J. Lin, N. Y. Yang, M. P. Houng and Y. H. Wang, “InGaP/InGaAs metal-oxide semiconductor pseudomorphic high-electron-mobility transistor with a liquid-phase-oxidized InGaP as gate dielectric,” IEEE Electron Dev. Lett., vol. 26, pp. 864-866, 2005.
[27]H. C. Lin, K. W. Lee, C. H. Tu, P. W. Sze and Y. H. Wang, “InGaP/InGaAs MOS-pHEMT with a liquid phase oxidized InGaP gate insulator,” in IEEE Conf. on Electron Devices and Solid-State Circuits (EDSCC), pp.181-184 , 2007.
[28]S. K. Ghandhi, VLSIFabrication Principles: Silicon and GalliumArsennide, New York: John Wiley & Sons, Inc., 1994.
[29]D. J. Coleman, D. W. Shaw and R. D. Dobott, “On the mechannism of GaAs anodization,” J. Electrochem. Soc., vol. 124, pp. 239-241, 1977.
[30]E. Kohn, “A correlation between etch characteristics of GaAs etch solutions containing and surface film characteristics,” J. Electrochem. Soc., Vol. 127, No. 2, 1980.
[31]J. R. Meyer-Arendt, Introduction to Classical and Modern Optics, Englewood Cliffs, N. J.: Prentice-Hall Inc., 1971.
[32]T. Sugano, “Oxidation of GaAs1-xPx surface by oxygen plasma and properties of oxide film,” J. Electrochem. Soc., vol. 121, pp. 113-118, 1974.
[33]M. Sadaka, D.l Hill, F. Clayton, H. Henry, C. Rampley, J .Abrokwah, and R. Uscola, “Development of Motorola’s InGaP HBT process,” GaAsMANTECH, Inc., 2002.
[34]L. H. Chu, E. Y. Chang, L. Chang, Y. H. Wu, S. H. Chen, H. T. Hsu, T. L. Lee, Y. C. Lien, and C. Y. Chang, “Effect of gate sinking on the device performance of the InGaP/AlGaAs/InGaAs enhancement-mode PHEMT,” IEEE Electron Device Lett., vol. 28, pp. 82-85, 2007.
[35]H. Willemsen and D. Nicholson, “GaAs ICs in commercial OC-192 equipment,” IEEE GaAs IC Symp. Tech. Dig., pp. 262-265, 1996.
[36]Y. J. Chan, and D. Pavlidis, ”Trap studies in GaInP/GaAs and AlGaAs/GaAs HEMT’s by means of low-frequency noise and transconductance dispersion characterization,” IEEE Trans. Electron Devices, vol. 41, pp. 637-642, 1994.
[37]H. K. Huang, Y. H. Wang,C. L. Wu, C. Wang, C. S. Chang, ”Super low noise InGaP gated PHEMT,” IEEE Electron Dev. Lett, vol. 23, pp. 70-72, 2002.
[38]K. Inoue, J. C. Harmand and T. Matsumo, “High-qualityInxGa1-xAs/InAlAs modulation-doped heterostrctures grown lattice-mismatched on GaAs substrates,” J. Crystal Growth, vol. 111, pp. 313-317, 1992.
[39]Y.-P. Zhao, G.C. Wang and T.M. Lu, “Surface-roughness effect on capacitance and leakage current of an insulating film,” Physical review B 60, p. 2, 1999.
[40]D. A. Neamen, Semiconductor Physics And Devices, Chapter 12, McGraw-Hill, 2003.
[41]I. Thayne, “Advanced III-V HEMTs,” The advanced semiconductor magazine, vol.16, pp. 48-51, 2003.
[42]C. L. Lau, M. Feng, T. R. Lepkowski, G. W. Wang, Y. Chang and C. Ito, “Half-micrometer gate-length ion-implanted GaAs MESFET with 0.8-dB noise figure at 16 GHz,” IEEE Electron Device Letters, vol. 10, pp. 409-411, 1989.
[43]F. N. Hooge, T. G. M. Kleinpenning, and L. K. J. Vandamme, “Experimental studies on l/f noise,” Rep. Prog. Phys., vol. 44, pp .480-530,1981.
[44]G. P. Zhigal'ski, “Nonequilibrium 1/f γ noise in conducting films and contacts,” Physics –Uspekhi, vol. 46, pp .449-471, 2003.
[45]F. N. Hooge, “l/f Noise Sources,” IEEE Trans. Electron Dev., vol. 40, pp. 1926–1935, 1994.