Optimisation of GaAs-based Power FETs with High Power Density and Power Efficiency


Keywords: FETs, microelectronics, surface passivation, low temperature growth

Start Date: 1 January 95 / Status: finished / Duration: 24 months

[ participants / contact]

Objectivies and Approach

The objective of this project is the implementation of novel low temperature grown materials into GaAs based microwave FETs (field effect transistors). Such device configurations have been shown to have a high potential for extremely high power densities. The material used is a low temperature molecular beam epitaxy grown GaAs or AlGaAs, displaying unique materials properties. This material is highly suitable as a surface passivation for GaAs based devices because it eliminates surface states related instabilities. The materials system and the technology are compatible with existing MMIC technologies but a fully satisfying surface passivation is still missing; however, a new perspective is given by this work.

European links: ESPRIT BRA project TAMPFETS (6849).

Progress and Results

A record 2.7 W/mm output power density has been demonstrated by low temperature GaAs dielectric FETs at 1MHz. The power capability observed in the quasi static regime is above this of conventional GaAs FETs by a factor of three. At small signal operation, a maximum frequency of oscillation in the range of 80 GHz has been measured for 1 m gate length devices. Based on these results, the main topics of this work are:

Current work focuses on the specific materials configuration, the optimum device structure and the optimum microwave performance.


Dept. of Electron Devices and Circuits
University of Ulm
Albert-Einstein-Alle 45
D-89069 Ulm, D

EU Partners

University of Ulm, D
Université des Sciences & Technique Lille, IEMN, F
University of Wales, UWCC, Cardiff, UK

Non-EU Partners

University of California, Santa Barbara, (US coordinator), USA
Case Western Reserve University, Cleveland, OH, USA


Prof. Erhard Kohn
Tel: +49 731502 6150
Fax: +49 731502 6155
E-mail: dept-ebs@sunrise.e-technik.uni-ulm.de

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HIPOFETS - EC-US047, May 1997

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html version of synopsis by Nick Cook