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ISSN Online: 2377-424X

ISBN Print: 0-85295-345-3

International Heat Transfer Conference 10
August, 14-18, 1994, Brighton, UK

EFFECT OF GATE VOLTAGE ON SHORT TIME AND LENGTH SCALE THERMAL PHENOMENA IN GaAs MESFETs

Get access (open in a dialog) DOI: 10.1615/IHTC10.4310
pages 315-320

Abstract

Metal-semiconductor field effect transistors (MESFETs) made of gallium arsenide (GaAs) are used in microwave devices, logic circuits and signal processing chips. The transistor operates by changing the gate voltage in the range 0 to -2 Volts which dramatically alters the source-to-drain electrical resistance. This paper studies the mechanisms of non-equilibrium Joule heating and heat flow in a GaAs MESFET with a gate length of 0.2 µm. Under a sourcc-to-drain bias of 3 Volts, the maximum electron temperature rise in this device is higher than 1000 K whereas the lattice temperature rise is of the order of 10 K, thereby exhibiting non-equilibrium characteristics. The high electron temperatures can reduce the current by 15 percent and must be included in the analysis. As the gate voltage is decreased from 0 to -2 Volts the maximum electron temperature increases due to generation of higher electric fields whereas the. maximum lattice temperature reduces due to lower power dissipation. More importantly, it is found that the electron temperature rise is nearly independent of the thermal package conductance whereas the lattice temperature rise depends strongly on it. In addition, an increase of lattice temperature by 100 K can reduce the drain current by 25 percent.