*Article* **Boron Impurity Deposition on a Si(100) Surface in a SiHCl3-BCl3-H<sup>2</sup> System for Electronic-Grade Polysilicon Production**

**Qinghong Yang 1,2,†, Fengyang Chen 1,2,†, Lin Tian <sup>3</sup> , Jianguo Wang 4,†, Ni Yang 1,3,\*, Yanqing Hou 1,\*, Lingyun Huang 1,\* and Gang Xie 2,3**


**Abstract:** A study of boron impurities deposited on a Si(100) surface in a SiHCl<sup>3</sup> -BCl<sup>3</sup> -H<sup>2</sup> system is reported in this paper, using periodic density functional theory with generalized gradient approximation (GGA). The results show that the discrete distances of BCl<sup>3</sup> and SiHCl<sup>3</sup> from the surface of the Si(100) unit cell are 1.873 Å and 2.340 Å, respectively, and the separation energies are −35.2549 kcal/mol and −10.64 kcal/mol, respectively. BCl<sup>3</sup> and SiHCl<sup>3</sup> are mainly adsorbed on the surface of the Si(100) unit cell in particular molecular orientations: the positive position and the hydrogen bottom-two-front position from the analysis of the bond length change and adsorption energy. The adsorption of SiHCl<sup>3</sup> and BCl<sup>3</sup> is accompanied by a charge transfer from the molecule to the surface of the unit cell of 0.24 and 0.29 eV, respectively. BCl<sup>3</sup> reacts more readily than SiHCl<sup>3</sup> with the Si(100) surface, resulting in the deposition of boron impurities on the polysilicon surface.

**Keywords:** electronic-grade polysilicon; boron impurities; chemical vapor deposition; density functional theory; differential charge density
