First-Principles Dissociation Pathways of BCl₃ on the Si(100)-2 × 1 Surface

Journal Article · Sun Dec 07 00:00:00 EST 2025 · Journal of Physical Chemistry. C

DOI:https://doi.org/10.1021/acs.jpcc.5c07066· OSTI ID:3018790

Campbell, Quinn T. ^[1]; Misra, Shashank ^[1]; Ivie, Jeffrey Andrew ^[1]

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1. Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)

BCl₃ is a promising acceptor precursor for atomic-precision δ-doping of silicon, as it has been observed to rapidly dissociate into boron doped into the silicon surface and surface chlorine, which can be removed upon annealing. The chemical pathway and the resulting kinetics, through which BCl₃ adsorbs and dissociates on silicon, however, have only been partially explained. Here, in this work, we use density functional theory to expand the dissociation reactions of BCl₃ to include reactions that take place across multiple silicon dimer rows and reactions which end in a bare B atom either at the surface, substituted for a surface silicon, or in a subsurface position. We further simulate the resulting scanning tunneling microscopy images for each of these BCl_x dissociation fragments, demonstrating that they often display distinct features that may allow for relatively confident experimental identification. Finally, we input the full dissociation pathway for BCl₃ into a kinetic Monte Carlo model, which simulates realistic reaction pathways as a function of environmental conditions, such as the pressure and temperature of dosing. We find that BCl₂ is broadly dominant at low temperatures, while high temperatures and ample space on the silicon surface for dissociation encourage the formation of bridging BCl fragments and B substitutions on the surface. This work provides the chemical mechanisms for understanding atomic-precision doping of Si with B, enabling a number of relevant quantum applications, such as bipolar nanoelectronics, acceptor-based qubits, and superconducting Si.

• Research Organization: Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)
• Sponsoring Organization: USDOE Laboratory Directed Research and Development (LDRD) Program; USDOE National Nuclear Security Administration (NNSA); USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities (SUF)
• Grant/Contract Number: NA0003525
• Other Award/Contract Number: 229375
• OSTI ID: 3018790
• Report Number(s): SAND--2026-15919J; 1776795
• Journal Information: Journal of Physical Chemistry. C, Journal Name: Journal of Physical Chemistry. C Journal Issue: 50 Vol. 129; ISSN 1932-7455; ISSN 1932-7447
• Publisher: American Chemical Society
• Country of Publication: United States
• Language: English