There is provided a biomolecule FET enhancing a sensitivity. The
biomolecule FET includes a substrate, first and second impurity regions
formed on both sides of the substrate, and doped with impurities of a
polarity opposite to that of the substrate, a gate formed on the
substrate and being in contact with the first and second impurity
regions, and a probe biomolecule attached to the gate. A region of the
gate adjacent to the first impurity region is wider than a region thereof
adjacent to the second impurity region. A density of the probe
biomolecule attached to the surface of the gate is increased, and when
detecting a level of hybridization of the probe biomolecule and the
target biomolecule, its sensitivity is improved.