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Adsorption behavior of molecules on 2 - dimensional materials such as graphene are a key factor influencing its potential for sensing application. This study reported the interaction of humidity molecules H$_2$O at different adsorption position on graphene/hexagonal boron nitride (hBN) that has been patterned with constriction simulated through Density Functional Theory (DFT). Three possible adsorption sites including those near to the constriction region was simulated and analyzed to evaluate its effect on the energy band gap variation, projected density of states (PDOS), adsorption energy, recovery time, charge transfer and current – voltage (I – V) characteristics. This was evaluated for both narrow and wide constriction in Graphene/hBN geometry. The simulation results indicate the electronic properties such as the energy and PDOS exhibit a minimal effect for all adsorption sites. However, the adsorption energy and charge transfer are found to be dependent on the adsorption sites particularly stable adsorption was achieved at both NC and WC edges. Although different adsorption sites exhibit noticeable variations in adsorption energy and charge transfer, they have only a minimal impact on the current response in the I–V characteristics. These findings demonstrate that the sensing layer geometry plays a significant role in tuning the sensitivity of Graphene/hBN-based devices.
