The density functional techniques (DFT) were put into practice to study the nature of the intermolecular interactions between Dichlorosilane (H2SiCl2) gas molecule with single-walled pristine, Al and Ga-doped boron nitride nanosheets (BNNS, BNAlNS, and BNGaNS, respectively). For performing optimization process, various functionals including PBE0, M06-2X, ωB97XD, and B3LYP-D3 were applied on both of the isolated and complex structures. All of the functionals were used together with split-valence triple-zeta basis sets with d-type Cartesian-Gaussian polarization functions (6-311G(d)). To consider the electronic structure, total density of state (DOS) analysis were employed. Natural bond orbital (NBO), quantum theory of atoms in molecules (QTAIM), and non-covalent interaction (NCI) analyses were also taken on board to discover the nature of intermolecular interactions between gas and nanosheets. The results of electronic structure calculations as well as population analyses has been carefully tabulated and partially depicted. The HOMO-LUMO energy gaps (HLG) were dramatically changed when the dopant atom added to the BNNS. It means the impurity can improve the sensivity and reactivity of the pristine nanosheet; therefore, by absorbing the H2SiCl2 onto the surface of the titled nanosheets, a salient signal can produce in a typical electronic circuit. Among all of the absorbents, BNGaNT shows the most favorable material to design a nanosensor for the studied gas molecule.