Atomistic dynamics of early oxidation of Si upon ultra-short pulsed laser heating
Year: 2026
Type: preprint
Abstract: Reactive molecular dynamics simulations are used to investigate the early stages of silicon oxidation under short-pulsed heating. Particular attention is devoted to the temperature range surrounding the melting threshold of silicon, where oxidation mechanisms undergo a profound transition. The simulations reveal two distinct regimes governed by the maximum surface temperature. Below the melting point, oxidation remains extremely limited due to the low mobility of oxygen in crystalline silicon, the absence of liquid-phase transport, and the short duration of the thermal transient. As a result, only a negligible oxide layer is formed. Once melting occurs, oxygen transport is dramatically enhanced by the emergence of a liquid silicon layer, leading to a rapid increase in oxidation rate. The thickness of the oxide layer is found to correlate with the molten-layer depth, indicating that oxygen diffusion within liquid silicon controls the early stages of oxide growth. Additionally, a nonlinear dependence on oxygen concentration is also observed, revealing a transition from oxygen-limited to diffusion-limited oxidation. Complementary, High-Resolution Electron Microscopy (HR-TEM) and Electron Energy Loss Spectroscopy (STEM-EELS) characterizations validate the computational insights revealing the formation of a continuous 2.3~nm oxide layer atop an amorphous silicon region on the bulk substrate. These findings provide a physical explanation for numerous experimental observations and demonstrate that thermally activated diffusion in the transient molten phase is the dominant mechanism governing short-pulse-induced oxidation at temperatures below 3000 K.
Source: Research Square
Language: English
Subfield: Industrial and Manufacturing Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7204433403