在此論文中，以Ga2O3(Gd2O3)為閘極，我們設計了二種結構，分別是GaAs和InGaAs/GaAs通道的空乏型砷化鎵金氧半導體場效電晶體。我們藉由改變氧化層的厚度，同一摻雜濃度下，比較單一通道和考慮能隙差距組成的雙通道對元件是否有更好的特性，和更明確的方向和做法。
此外，我們也成功的製作出Ga2O3(Gd2O3)/GaAs和Ga2O3(Gd2O3)/ In0.15Ga0.85As/GaAs的空乏型金氧半導體場效電晶體，並量測其直流特性，並且發現最後的退火過程對元件有很大的影響性。
對於閘極寛度為100um，長度為1.6um的Ga2O3(Gd2O3)/GaAs電晶體，在閘極電壓為4V時，室溫下有很大的堆積(acculmulation)飽和汲極電流(Idss)為335mA/mm，最大轉導(transconductance)為130mS/mm在汲極等於3V時，元件的截止電壓為-3V，而元件的崩潰電壓為15V，而在用Forming Gas(氮氣85%和氫氣15%的混合物)退火三小時後，得到很低並且對稱的漏電流約10-6A。
另外在同一尺寸的Ga2O3(Gd2O3)/ In0.15Ga0.85As/GaAs電晶體，在閘極電壓為1V時，室溫下飽和汲極電流(Idss)為115mA/mm， 而加入遷移率較大的InGaAs得到較大的轉導(transconductance)為170mS/mm。而以上的元件在汲極電壓來回量測時，都顯示沒有汲極電流飄移的現象。

In this thesis, using Ga2O3(Gd2O3) as a gate dielectric, we have designed two different structures of depletion-mode(D-mode) GaAs MOSFET's, with GaAs and InGaAs/GaAs as channels. By changing the thickness of oxide, but retaining the same doping concentration, the effects of different channel design on device performance were investigated. Future work is being planned to to improve it.
We have sucessfully fabricated D-mode Ga2O3(Gd2O3)/GaAs and Ga2O3(Gd2O3)/ In0.15Ga0.85As /GaAs MOSFET's. In addition, we have found out that a great improvement on device characteristics was achieved with a final annealing.
D-mode GaAs MOSFET’s with Ga2O3(Gd2O3) as a gate dielectric, a dimension of 1.6 um x 100 um, have shown high accumulation currents of 335 mA/mm at a gate bias of VG = 4V, transconductance of over 130 mS/mm when Vd=3V, pinch-off voltage of -3V, and the device breakdown voltage of over 15V. Also, gate leakage current versus biasing voltage of the fabricated device shows a symmetrical behavior in 10-6A range after forming gas annealing for 3 hours.
Ga2O3(Gd2O3)/ In0.15Ga0.85As /GaAs MOSFET has drain saturated current of 115mA/mm, and a maxmimum transconductance of 171 mS/mm was achieved by inserting an In0.15Ga0.85As channel layer between oxide and the GaAs channel with the same device dimension.
In this work, we report the first achievement of a strong accumulation current at Vg larger than 3 V in a D-mode GaAs MOSFET and both devices have shown no hysteresis in drain currents.

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3.“Demonstration of enhancement-mode p- and n-channel GaAs MOSFETs with Ga2O3(Gd2O3) as gate oxide”, F. Ren, M. Hong, W. S. Hobson, J. M. Kuo, J. R. Lothian, J. P. Mannaerts, J. Kwo, S. N. G. Chu, Y. K. Chen, and A. Y. Cho, Solid State Electronics, 41 (11), 1751, 1997.

4.“Advances in GaAs MOSFETs using Ga2O3(Gd2O3) as gate oxide”, Y. C. Wang, M. Hong, J. M. Kuo, J. P. Mannaerts, J. Kwo, H. S. Tsai, J. J. Krajewski, J. S. Weiner, Y. K. Chen, and A. Y. Cho, in “Compound semiconductor surface passivation and novel device processing”, Volume 573, 219-226, Ed. by H. Hasegawa, M. Hong, Z. H. Lu, and S. Pearton. An invited paper at Symposium Z of Materials Research Society 1999 Spring Meeting, April 5-7 at San Francisco, CA.

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6.“Demonstration of sub-micron depletion-mode GaAs MOSFET’s with negligible drain current drift and hysteresis”, Y. C. Wang, M. Hong, J. M. Kuo, J. P. Mannaerts, J. Kwo, H. S. Tsai, J. J. Krajewski, Y. K. Chen, and A. Y. Cho, IEEE Electron Device Letters, 20, 457-459, 1999.

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8.“Properties of Ga2O3(Gd2O3)/GaN MIS Diodes”, M. Hong, K. A. Anselm, J. P. Mannaerts, J. Kwo, A. Y. Cho, A. R. Kortan, C. M. Lee, J. I. Chyi, and T. S. Lay, J. Vac. Sci. Technol. B18, 1453, 2000. (presented at 18th NAMBE)

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14.“Novel Ga2O3(Gd2O3) passivation techniques to produce low Dit oxide-GaAs interfaces", M. Hong, J. P. Mannaerts, J. E. Bowers, J. Kwo, M. Passlack, W-Y. Hwang, and L. W. Tu, J. Crystal Growth, 175/176, 422-427, 1997.

15.“Structural properties of Ga2O3(Gd2O3)-GaAs interfaces”, M. Hong, J. P. Mannaerts, M. A. Marcus, J. Kwo, A. M. Sergent, L. J. Chou, K. C. Hsieh, and K. Y. Cheng, J. Vac. Sci. Technol. B16(3), 1395, 1998.

16.“Low Dit thermodynamically stable Ga2O3-GaAs interfaces: fabrication, characterization, and modeling”, M. Passlack, M. Hong, J. P. Mannaerts, J. Kwo, R. L. Opila, S. N. G. Chu, N. Moriya, and F. Ren, IEEE Transaction of Electron Devices, 44 No. 2, 214-225, 1997.

17.“Thermodynamic stability of Ga2O3.Gd2O3./GaAs interface”, Y. L. Huang, P. Chang, Z. K. Yang, and Y. J. Lee, H. Y. Lee and H. J. Liu, J. Kwo, J. P. Mannaerts and M. Hong, APL, (86), 191905, 2005

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19.“Quasi-static and high frequency capacitance-voltage characterizationof Ga2O3-GaAs structures fabricated by in-situ molecular beam epitaxy”, M. Passlack, M. Hong, and J. P. Mannaerts, Appl. Phys. Lett. 68(8), 1099, 1996.

20.“Passivation of GaAs using (Ga2O3)1-x(Gd2O3)x (x=0 – 1.0) films”, J. Kwo, D. W. Murphy, M. Hong, R. L. Opila, J. P. Mannaerts, R. L. Masaitis, and A. M. Sergent, Appl. Phys. Lett., 75, p.1116, 1999.

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22.“Structure of epitaxial Gd2O3 films and their registry on GaAs (100) substrates”, B. Bolliger, M. Erbudak, M. Hong, J. Kwo, A. R. Kortan, and J. P. Mannaerts, Surface and Interface Analysis, 30, 514, 2000. (The paper was presented at the 8th European Conf. Proc. On Application of Surface and Interface Analysis, Oct. 4-8, Svelle, Spain, 1999.)

23.“Initial growth of Ga2O3(Gd2O3) on GaAs – key to the attainment of a low Interfacial density of states” M. Hong, Z. H. Lu, J. Kwo, A. R. Kortan, J. P. Mannaerts, J. J. Krajewski, K. C. Hsieh, L. J. Chou, and K. Y. Cheng, Appl. Phys. Lett. 76 (3), 312, 2000.

24.“Energy-band parameters at the GaAs- and GaN-Ga2O3(Gd2O3) interfaces”, T. S. Lay, M. Hong, J. Kwo, J. P. Mannaerts, W. H. Hung, and D. J. Huang, Solid State Electronics, 2001.

25.“Growth of Ga2O3(Gd2O3) using molecular beam epitaxy techniques - Key to first demonstration of GaAs MOSFETs", M. Hong, F. Ren, W. S. Hobson, J. M. Kuo, J. Kwo, J. P. Mannaerts, J. R. Lothian, M. A. Marcus, C. T. Liu, A. M. Sergent, T. S. Lay, and Y. K. Chen, Invited paper at 24th IEEE International Symposium on Compound Semiconductors, IOP series 97TH8272, Bristol and Philadelphia, 1997, 319-324.

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32.“Optimization of AuGe/Ni/Au ohmic contacts for GaAs MOSFETs”, H. C. Lin, S. Senanayake, and K. Y. Cheng, M. Hong, J. Kwo, B. Yang, and J. P. Mannaerts, accepted for publication in IEEE Trans. Electron Dev., January, 2003.

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