臺灣博碩士論文加值系統

在本論文中，我們研究以「金屬有機化學氣相沉積法」成長的高載子遷移率電晶體，它使用階梯狀結構的通道層，以改善電晶體的特性。
當我們使用階梯狀結構的通道層時，通道傳導帶將會形成V字型的谷，而通道中的大部分電子會聚集在V型的谷底，因此二維電子雲會較遠離AlGaAs/InGaAs的接面，庫侖散射（Coulomb scattering）會降低，而提高電子遷移率，所以可獲得高的電流密度和增益，同時階梯狀結構的通道層會增加閘極工作電壓擺幅（gate voltage swing）。
在室溫下，閘極的尺寸為1.2×100 ?m2時，元件的最大汲極飽和電流為385 mA/mm，最大轉導值為148 mS/mm，且可得閘極工作電壓擺幅?1.9伏特。另外閘極和汲極兩端的崩潰電壓為16伏特。我們也同時描述了元件的高頻特性，截止頻率為9.5GHz，最大振盪頻率為37GHz。
使用階梯狀結構的通道層結構的高載子遷移率電晶體顯示了良好的特性，使元件預期可以利用於高速和放大器的應用。

In this thesis, the high electron mobility transistors (HEMT’s) with step-composition channel grown by metalorganic chemical vapor deposition (MOCVD) have been studied. The improvement can be expected by using a novel channel structure.
By using the step graded channel the electrons in the channel will be confined well in the bottom of the V-shape conduction band. The electrons are also far away from the AlGaAs/InGaAs interface, thus Coulomb scattering is reduced. Consequently the electron mobility will increase. Then the high drain current density and large gate voltage swing can be obtained.
For a 1.2×100 μm2 gate dimension, the maximum saturation drain current density is 385 mA/mm and the maximum extrinsic transconductance is 148 mS/mm along with the gate voltage swing of 1.9V. Besides, the gate-to-drain breakdown voltage of 16 V is obtained.
The microwave performance of our structure is also described. The current gain cut-off frequency ( ) and maximum oscillation frequency ( ) are 9.5 GHz and 37 GHz, respectively.
These good performances show that the studied structure with step-composition channel HEMT has good potential for high speed and amplification capability.

Abstract (Chinese)
Abstract (English)
Figure Caption
Chapter 1 Introduction
Chapter 2 LP-MOCVD System
2-1 System Introduction
2-1-1 The Gas Handling System
2-1-2 The Bypass Pipe Line
2-1-3 The Reaction Chamber and Heating System
2-1-4 The Automatic Pressure Control (APC) System
2-1-5 The Gas Exhaust System
2-2 Epitaxy Growth
Chapter 3 Design of the Conventional InGaAs channel PHEMTs
3—1 Introduction to HEMTs
3—2 Design of PHEMT Layer
3—2—1 Undoped Buffer Layer
3—2—2 InGaAs Pseudomorphic Channel Layer
3—2—3 Undoped Spacer Layer
3—2—4 n+—Schottky Layer
3—2—5 n+—Capping Layer
3—3 Principles of PHEMTs
3—3—1 Charge Transfer
3—3—2 2DEG Charge Control
3—3—3 Mobility Determining Process
Chapter 4 Device Structures and Device Processes
4—1 Device Structures
4—2 The Improvements of Structures
4—2—1 Delta—Doped
4—2—2 Step-Composition Channel
4—2—3 AlGaAs/GaAs Buffer Layer
4—3 Devices Process
4—3—1 Sample Orienting
4—3—2 Mesa Isolation
4—3—3 Source and Drain Metallization
4—3—4 Form Gate Schottky Contact
4—4 Hall Measurement
Chapter 5 Experimental Results and Discussions
5—1 Sample A (without step-composition channel)
5—2 Sample B (with step-composition channel)
5—3 The Comparison with Samples
5—4 The Characteristic in Different Temperature
5—5 The RF Characteristic
Chapter 6 Conclusion
References
Figure

[1]R. Dingle, H. L. Stormer, A. C. Gossard, and W. Wiegmann, “Electron mobilities in modulation-doped semiconductor heterojuncyion superlattices”, Appl. Phys. Lett., vol. 33, pp. 665-667, 1978.
[2]W. C. Hsu, C. L. Wu, M. S. Tsai, C. Y. Chang, W. C. Liu, and H. M. Shieh. “Characterization of high performance inverted delta-modelation-doped (IDMD) GaAs/InGaAs pseudomorphic heterostructure FET’s”, IEEE Trans. Electron Devices vol. 42, pp. 804-809, 1995.
[3]Park, D.H., and Brennan, K. F., “Theory of electronic transport in two-dimensional Ga0.85In0.15As/Al0.15Ga0.85As pseudomorphic structure”, J. Appl. Phys., vol. 65 (4), pp.1615-1620, 1989.
[4]F. Ali and A. Gupta, “HEMTs and HBTs; Devices, Fabrication, and Circuits”, Artech House, Boston London, 1991.
[5]S. M. Sze, “Physics of semiconductor devices”, 2nd Edition, John Wiley & Sons, 1985.
[6]S. R. Bahl, W. J. Azzam, and J.A. del Alamo, “Stained-insulator InxAl1-xAs/n+-In0.53Ga0.47As heterostructure field effect transistor”, IEEE Trans. Electron Devices, vol. 41, pp. 2268-2275, 1994.
[7]L. J. Giling, “Gas flow patterns in horizontal epitaxial reactor cell observed by interference holography”, J. Electrochem. Soc., vol. 129, pp.634, 1982
[8]L. Stock and W. Richter, “Vertical versus horizontal reactor; an optical study of the gas phase in a MOCVD reactor”, J. Cryst. Growth, vol. 77, pp.144, 1986.
[9]R. Menozzi, M. Borgarino, P.Cova, Y. Baeyens, and F. Fantini, “The effect of hot electron stress on the Dc and microwave characteristics of AlGaAs/InGaAs/GaAs PHEMTs”, Microelectron. Reliab., vol. 36, pp. 1899-1902, 1996.
[10]C. Tedesco, E. Zanoni, C. Canali, S. Bigliardi, M. Manfredi, D. C. Streit, and W. T. Anderson, “Impact ionization and light emission in high-power pseudomorphic AlGaAs/InGaAs HEMT’s”, IEEE Trans. Electron Devices vol. 40, pp. 1211-1214, 1993.
[11]N. X. Nguyen, W. N. Jiang, K. A. Baumann, and U. K. Mishra, “High-breakdown AlGaAs/InGaAs/GaAs PHEMT with tellurium doping”, Electron. Lett., vol. 31, pp. 586-588, 1995.
[12]C. Y. Chang, and F. Kai, “GaAs high-speed devices”, John Wiley & Sons, 1994.
[13]Y. J. Jeon, Y. H. Jeong, B. Kim, Y. G. Kim, W. P. Hong, M. S. Lee, “DC and RF performance of LP-MOCVD grown Al0.25Ga0.75As/InxGa1-xAs (x=0.15-0.28) P-HEMT''s with Si-delta doped GaAs layer”, IEEE Electron Device Lett., vol. 16, pp. 563 -565 1995.
[14]Y. W. Chen, W. C. Hsu, H. M. Shieh, Y. J. Chen, Y. S. Lin, Y. J. Li, T. B. Wang, “High breakdown characteristic δ-doped InGaP/InGaAs/AlGaAs tunneling real-space transfer HEMT”, IEEE Electron Device Lett., vol. 49, pp. 221-225, 2002.
[15]W. C. Liu, W. L. Chang, W. S. Lou, H. J. Pan, W. C. Wang, J. Y. Chen, K. H. Yu, S. C. Feng, “High-performance InGaP/InxGa1-xAs HEMT with an inverted delta-doped V-shaped channel structure”, IEEE Electron Device Lett., vol. 20, pp.548-550, 1999.
[16]B. G. Streetman, and Y. C. shih, “Measurement of abrupt transition in III-V compounds and heterostructures”, J. Vac. Sci. Technol. B, vol. 10, pp. 296-301 1992.
[17]L. W. Laih, S. Y. Cheng, W. C. Wang, P. H. Lin, J. Y. Chen, W. C. Liu, and W. Lin, “High-performance InGaP/InGaAs/GaAs step-compositioned doped channel field-effect transistor (SCDCFET)”, Electron. Lett., vol. 33, (1) pp. 98-99, 1997.
[18]J. C. Liou, and K. M. Lau, “Temperature dependence and persistent conductivity of GaAs MESFET’s with superlattice Buffers”, IEEE Trans. Electron Devices vol. 35, pp. 14-17, 1988.
[19]W. C. Hsu, H. M. Shieh, M. J. Kao, R. T. Hsu, Y. H. Wu, “On the improvement of gate voltage swings in δ-doped GaAs/In xGa1-xAs/GaAs pseudomorphic heterostructures”, IEEE Trans. Electron Devices vol. 40, pp. 1630-1635, 1993.
[20]C. L. Wu, W. C. Hsu, H. M. Shieh, M. S. Tsai, “An improved inverted δ-doped GaAs/InGaAs pseudomorphic heterostructure grown by MOCVD”, IEEE Electron Device Lett., vol. 15, pp. 330-332, 1994.
[21]M. Feng, D. R. Scherrer, P. J. Apostolakis, J. W. Kruse, “Temperature dependent study of the microwave performance of 0.25 μm gate GaAs MESFETs and GaAs pseudomorphic HEMTs”, IEEE Trans. Electron Devices vol. 43, pp. 852, 1996.
[22]R. Menozzi, M. Borgarino, Y. Baeyens, M. Van Hove, F. Fantini, “On the effects of hot electrons on the DC and RF characteristics of lattice-matched InAlAs/InGaAs/InP HEMTs”, IEEE Microwave and Guided Wave Lett., vol. 7, pp. 3, 1997.