In this work, a new simulation approach of transient analysis on single cavity dielectric-modulated (DM) p-type of tunnel field-effect transistor (TFET) is examined for biosensing applications. The device operation and performance are investigated using the 2D device simulator and results are well-calibrated with experimental data. In this work, we have examined DC transfer characteristics, the transient response of drain current, drain current sensitivity (S), and selectivity (Δ S). Focussing more on the transient results, we have obtained maximum sensitivity of orders greater than 108 for APTES biomolecule with respect to air and a significant selectivity value in orders of 103 for APTES with respect to Biotin biomolecule. The performance of the device in terms of selectivity can be further improved (104) by optimizing the back-gate bias, and therefore, the impact of back-gate bias has been analysed. The results for charged biomolecules and partially filled cavity are further investigated highlighted. The DM p-TFET biosensor shows a significant improvement in the results with the transient response for biosensing applications with the feasibility of operating at low voltages (gate voltage of-2.0 V, drain voltage of-0.5 V and back gate voltage 0 to 0.5 V). © 2001-2012 IEEE.