Performance assessment of cavity on source dual material split gate GaAs/InAs/Ge junctionless TFET for label-free detection of biomolecules

This article proposes and investigates a cavity on source dual-material split gate GaAs/InAs/Ge Junctionless tunnel field-effect transistor (CS-DMSG-GaAs/InAs/Ge-JLTFET) biosensor for label-free detection of biomolecules using technology computer-aided design (TCAD) simulations. This device employs an InAs pocket at the source-channel interface to create a narrow tunneling barrier. A nanocavity has been created on the source side within the dielectric oxide of the polarity gate (p-gate) by etching some portion of the oxide at the tunneling junction interface to improve the sensitivity of the proposed biosensor. The gate region is split into two parts named the fixed gate (f-gate) and the control gate (c-gate), the work function variation between the f-gate and the c-gate causes band structure modification to improve sub-threshold swing (SS) and band-to-band (BTBT) tunneling current. The f-gate causes a local dip at the edge of the conduction band, resulting in sharp band bending near the InAs/GaAs interface. The simulation results demonstrate that the proposed device offers lower SS and lower threshold voltage (V-T). The work function engineering concept has been used for the formation of P+ and N+ regions (source and drain) in the proposed device. The high-k dielectric oxide (HfO2) is used at the p-gate to attain higher ON-current (I-ON) and improve the sensitivity of the proposed biosensor. The sensing performance of the proposed biosensor has been analyzed in terms of drain current, SS, and I-ON/I-OFF ratio. One of the practical challenges of biosensors, such as partially filled cavities, is also analyzed. Different types of neutral biomolecules, such as uriease (k = 1.64), streptavidin (k = 2.1), biotin (k = 2.63), ferrocytochrome c (k = 4.7), bacteriophage T7 (k = 6.3), keratin (k = 8) and gelatin (k = 12) and charged biomolecules with positive and negative charges, are considered to analyze the performance of the proposed biosensor. Simulation results indicate that the proposed biosensor can be a potential candidate for low-power high-performance sensing devices.