Thermal simulation and characterization of GaAs micromachined power-sensor microsystems

Thermal characteristics of GaAs power-sensor microsystems based on a three-terminal thermoconversion principle are studied by simulation and experiment. The sensor consists of two MESFET heaters and a Schottky diode temperature detector placed on each of two identical micromachined cantilever beams. The sensor power-temperature dependences, cantilever-to-cantilever heat-transfer characteristics and thermal time constant are obtained from electrical and time-domain optical reflectivity measurements in different ambient atmospheres. A laser interferometric technique is used to evaluate the temperature in the cantilever active area via Fabry-Perot intensity changes. The spatial temperature distribution in the cantilever, thermal time constant, power-temperature dependences and mutual cantilever-to-cantilever transfer characteristics are calculated from the time-dependent solution of a two-dimensional heal-flow equation including the effect of different gaseous media. The experimental results are found to be in good agreement with the simulation. (C) 1998 Elsevier Science S.A. All rights reserved.