具共平面波導設計之場效應控制電子轉移元件之研究

Abstract

為促進單晶微波積體電路之發展，本文提出一具有共平面波導設計之場效 應控制電子轉移元件之研究。此元件包括共平面波導之設計、歐姆性陰極 接觸及蕭特基閘極和陽極接觸。並藉由縮短陰極與閘極的距離，改善輸出 功率。在設計方面，我們考慮基座的有效介質常數、閘極金屬條的寬度及 兩金屬條之間的距離，設計了一具有五十歐姆特性阻抗、並可和外部電路 匹配使其能量損失最小化之元件。再依製程技術製造此元件。最後，我們 測量在不同的閘極到陽極距離的直流特性，並討論之。結果顯示，具蕭特 基陽極接觸的元件，將出現負電阻的特性。而且，如果半絕緣砷化鎵基座 上有二層主動磊晶層時，我們觀察到電流電壓特性曲線將變成二個負電阻 區域。 For advancing the development of monolithic microwave integrated circuits (MMICs), field effect controlled transferred electron devices(FECTEDs) combined with the design of coplanar waveguide have been proposed in this paper. This device includes the design of coplanar waveguide, ohmic cathode contact, Schottky gate and anode contact. In addition to these structures, we can improve the output power by reducing the distance between the cathode and the gate. In the concept of design, we considered the effective dielectric constant (ε_re) on the substrate, the width of gate strip, and the distance between strips. We designed a coplanar waveguide with 50 Ω characteristic impedance which can match the external circuits and minimize the energy loss. Than we use the process technology to fabricate a FECTED. The I-V curve characteristics under different distance between gate and anode are measured and discussed carefully. The results show that the device with the Schottky anode contact will have the phenomenon of negative resistance in the I-V curve. It is observed that the I-V curve will have two negative resistance portions if the active layer of the GaAs wafer consists two epitaxial layers(n+/n) on the semi-insulating substrate.