Optimization of the permittivity-based BE SOI biosensor

This paper explores for the first time how the electrical characteristic of the BE (Back Enhanced) SOL MOSFETs (n- and p-type) is affected by the introduction of materials with different permittivities, aiming the biological sensing application. The BE SOL MOSFET is a planar undoped SOI device whose working principle is based on the electrical field interaction between the substrate and the front gate. The biomaterial is deposited on the underlap region between source/drain and gate to be sensed. Simulations of the BE SOL were performed using the experimental data. In the dimensions studied range, the best biosensor sensitivities as a function of the relative permittivity are obtained for the thinnest silicon film (5nm) and shortest underlap length (100nm). Other parameters influence on sensitivities like front and back gate oxide thicknesses and transistor channel dimensions are negligible.