  In this letter, we propose a dielectric-modulated Impact-Ionization MOS
(DIMOS) transistor based sensor for application in label-free detection of
biomolecules. Numerous reports exist on the experimental demonstration of
nanogap-embedded FET-based biosensors, but an I-MOS based biosensor has not
been reported previously. The concept of a dielectric-modulated I-MOS based
biosensor is presented in this letter based on TCAD simulation study. The
results indicate a high sensitivity to the presence of biomolecules even at
small channel lengths. In addition, a low variability of the sensitivity to the
charges on the biomolecule is observed. The high sensitivity, dominance of
dielectric-modulation effects and operation at even small channel lengths makes
the DIMOS biosensor a promising alternative for CMOS-based sensor applications.
