Integrated MOS Chemical Sensors Utilizing Inorganic Insertion Compounds
Project Title:Integrated MOS Chemical Sensors Utilizing Inorganic Insertion Compounds
Company:EIC Laboratories, Inc.
Norwood, MA 02062
Principal Investigator:Rauh, R. David
Solid state chemical sensors based on chemically active thin films incorporated as
gate metals in field effect transistors would be useful as gas analyzers for robotic
planetary explorers and cabin/station atmospheres. These devices can be subject
to micromineaturization, and integrated into circuits containing, on a single chip,
all calibration, analysis and readout functions. The problem with present sensors
of configuration CATALYTIC METAL/SiO2/Si is their lack of specificity and long term
instability. We propose to inestigate new structures where an insertion compound
is interposed between the metal and the SiO2. The insertion compound is chosen to
be selective of molecule or atom size or structure. The insertion layers of interest
also undergo a change in electrical conductivity on insertion of the species to be
sensed or its biproduct into its crystalline lattice. These reactions are highly
reversible. The result is a change in the capacitance of the metal-insulator-semiconductor
structure, which is ultimately realized as a change in source-drain current in a
field effect transistor. In Phase I, it is proposed to survey a variety of catalytic
metal/insertion compound bilayers in simple MIS diode structures for chemical sensitivity
with improved selectivity, reversibility and stability compared to present technology.
Phase II will be employed to study the fabrication of diode arrays and the use of
pattern recognition logic to interpret array response for analysis of gaseous mixtures.