Date of Award

Fall 1997

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Electrical Engineering - (Ph.D.)

Department

Electrical and Computer Engineering

First Advisor

Ken K. Chin

Second Advisor

William N. Carr

Third Advisor

Haim Grebel

Fourth Advisor

Edip Niver

Fifth Advisor

Marek Sosnowski

Sixth Advisor

Jenn-Ming Kuo

Seventh Advisor

Erhard Kohn

Abstract

Improving performance and suppressing short channel effects are two of the most important issues in present field effect transistors development. Hence, high performance and long channel like behaviors are essential requirements for short channel FETs. This dissertation focuses on new ways to achieve these significant goals. A new field effect transistor - dual material gate FET (DMG-FET) - is presented for the first time. The unique feature of the DMG-FET is its gate which consists of two laterally contacting gate materials with different work functions. This novel gate structure takes advantage of material work function difference in such a way that charge carriers are accelerated more rapidly in the channel and the channel potential near the source is screened from the drain bias after saturation. Using HFET as a vehicle, it is shown that the drive current and transconductance in DMG-FET are therefore substantially enhanced as compared to conventional FET. Moreover, it is observed that the short channel effects such as channel length modulation, DIBL and hot-carrier effect are significantly suppressed. Numerical simulations are employed to investigate the new device structure and related phenomenon. A simple and practical DMG-HFET fabrication process has been developed. The proposed DMG-HFET is thus realized for the first time. Experimental results exhibit improved characteristics as the simulation results predicted.

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