TITLE

Magnetoresistance method to determine GaAs and AlxGa1-xAs mobilities in AlxGa1-xAs/GaAs modulation-doped field-effect transistor structures

AUTHOR(S)
Look, D. C.; Norris, George B.; Kopp, W.; Henderson, T.; Morkoç, H.
PUB. DATE
August 1985
SOURCE
Applied Physics Letters;8/1/1985, Vol. 47 Issue 3, p267
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
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 Al[sub 0.3] Ga[sub 0.7] As/GaAs modulation-doped FET (MODFET). By analyzing the results at different magnetic fields, we can separate the contributions of the various GaAs subbands and the Al[sub 0.3] Ga[sub 0.7] As conduction band. In the particular MODFET structure studied here, the lowest GaAs subband mobility ranges from 5.7 × 10³ cm²/Vs at threshold to 6.9 × 10³ cm²/Vs at saturation, while the Al[sub 0.3]Ga[sub 0.7]As mobility is about 5 × 10² cm²/Vs. This is the first time that the various mobilities in MODFET structures have been separately measured.
ACCESSION #
9817866

 

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