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Charge carrier mobilities are conveniently measured in simple, homostructure field-effect transistors (FET's) by means of the geometric magnetoresistance (GMR) technique. Heterostructure FET's, however, are more complicated because of multiple conducting regions, as well as multiple conducting bands within a given region. We apply a multilayer GMR mobility model to a frequently used heterostructure FET design, namely, the Al0.3Ga0.7As conduction band. In the particular MODFET structure studied here, the lowest GaAs subband mobility ranges from 5.7X103 cm2/Vs at threshold to 6.9X103 cm2/Vs at saturation while Al0.3Ga0.7As mobility is about 5X102 cm2/Vs. This is the first time that the various mobilities in MODFET structures have been separately measured.


Copyright © 1985, American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Applied Physics Letters 47.3, and may be found at



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