Stacked split gate oxide DG P–I–N Hetero-Vertical TFET based gas sensor for sensing O2, H2 and NH3

Abstract

In this reported work, we have proposed doping less channel based Splitting gate oxide double Gate-Hetero V-TFET gas sensor and analyzed its different figures of merit by using the TCAD simulation tool. The incorporation of doping-less channel intended to provide high on-state current and improve the switching performance. Splitting gate oxide (oxide layer is sandwiched between two high-κ layers) used in this structure reduces power consumption, lowers interface state density and improves the surface passivation for the proficient tunnelling. When gas material is present, gas molecules dissociate and are absorbed into the catalytic gate metal of the device through the diffusion process. Vertical device structure takes lower chip area as compared to lateral device; thus, more devices can be accommodated in same chip area. Here, gate metal surface gas molecule adsorption impact on surface potential, electric field, threshold voltage, and energy band structure were explored. Cobalt (WF = 4.7eV), Silver (WF = 5.0eV) and Palladium (WF = 5.1eV) were used as gate metals for the sensing of Ammonia, Oxygen, and hydrogen gases respectively. Proposed gas sensor with gate metals as Cobalt, Silver, and Palladium under the unexposed condition has a high I_ON/I_OFF current ratio (∼9.46 × 10¹², 2.64 × 10¹², and 1.13 × 10¹²). While same device on gas exposure to above mentioned gases at gas concentration corresponding to 200 meV work function change shows a low I_ON/I_OFF current ratio (∼5.14 × 10¹², 4.00 × 10¹¹, and 1.06 × 10¹¹) with a decent SS (21.16 mV/dec). Thus, proposed gas sensor is highly sensitive and shows a distinguishable change in device current under exposed and unexposed condition.