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Investigation of Nanometric Thin-Film Bismuth Piezoresistors Deposited on Silicon Substrates

Published online by Cambridge University Press:  03 January 2013

Horacio V. Estrada
Horacio V. Estrada*
Affiliation:
Centro Nacional de Metrología (CENAM), Querétaro, QRO 76246, MEXICO.
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Abstract

Thin film bismuth piezoresistors, defined on oxidized silicon wafers, are investigated as a function of their orientation for their eventual integration on micro-electro-mechanical (MEMS) microsensors. Bismuth’s piezoresistance (or elasto-resistance) is experimentally investigated to accurately determine its longitudinal and transverse strain sensitivities. Whisker-shaped resistive elements defined on different orientations (from 0o, the beam’s main strain axis, to 90o, perpendicular to that axis) undergo changes of resistance (ΔR), associated with the induced strains on silicon cantilevers beam’s surface when these are mechanically loaded under pure bending stress conditions. For Bi-resistors, the traditional gage factor concept, (ΔR/Ro)/εl, is found to be equal to +16 and +33, for elements oriented along 0 and 90o, respectively, considerably larger than those for metals or metal alloys. These high sensitivity values and the “unusual” positive, higher value for the 90o (perpendicular) resistors can be of considerable interest for microsensors applications. The results of this study enable us to precisely determine the bismuth’s longitudinal and transverse strain sensitivities that are calculated to be equal to +26 and +40.5 respectively. This experimental study is extended to explore the Bi-films’ response to bi-axial strain fields.

Keywords

piezoresponsesensorBi
Type
Articles
Information
MRS Online Proceedings Library (OPL) , Volume 1477: Symposium S1A – Low-Dimensional Bismuth-based Materials , 2012 , imrc12-1477-s1a-o037
Copyright
Copyright © Materials Research Society 2012 

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References

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