Atomic-Scale Origins of Oxidation Resistance in Amorphous Boron Nitride

TL;DR

This work addresses the atomistic origins of oxidation resistance in amorphous BN by linking synthesis-driven morphology to oxidative stability. It combines a Gaussian Approximation Potential–driven MD framework with melt–quench protocols and oxidation cycles and validates the predictions with angle-resolved XPS on CVD-grown films. The results show that dense, B–N–rich networks resist oxidation and confine oxygen to near the surface, while defect-rich, B–B/N–N-rich networks enable deeper oxygen penetration and bulk degradation; higher-temperature growth yields more ordered, near-stoichiometric B/N environments and enhanced surface protection. Together, these findings demonstrate that oxidation resistance in α‑BN can be tuned via synthesis parameters, offering a framework for designing chemically robust ultrathin dielectric barriers for next-generation nanoelectronics.

Abstract

Amorphous boron nitride (\textrm{$α$}-BN) is a promising ultrathin barrier for nanoelectronics, yet the atomistic mechanisms governing its chemical stability remain poorly understood. Here, we investigate the structure-property relationship that dictates the oxidation of \textrm{$α$}-BN using a combination of machine-learning molecular dynamics simulations and angle-resolved X-ray photoelectron spectroscopy. The simulations reveal that the film structure, controlled by synthesis conditions, is the critical factor determining oxidation resistance. Dense, chemically ordered networks with a high fraction of B-N bonds effectively resist oxidation by confining it to the surface, whereas porous, defect-rich structures with abundant homonuclear B-B and N-N bonds permit oxygen penetration and undergo extensive bulk degradation. These computational findings are consistent with experimental trends observed in \textrm{$α$}-BN films grown by chemical vapour deposition. XPS analysis shows that a film grown at a higher temperature develops a more ordered structure with a B/N ratio nearer to stoichiometric and exhibits superior resistance to surface oxidation compared to its more defective, lower-temperature counterpart. Together, these results demonstrate that the oxidation resistance of \textrm{$α$}-BN is a tunable property directly linked to its atomic-scale morphology, providing a clear framework for engineering chemically robust dielectric barriers for future nanoelectronic applications.

Figures (8)

• Figure 1: Impact of quenching rate on the initial structure of $\alpha$-BN films. (a) Fraction of atoms in $sp$, $sp^2$, and $sp^3$ hybridization states. (b) Percentage of B–N, B–B, and N–N bonds. (c) B/N atomic ratio. (d) Mass density (g cm$^{-3}$).
• Figure 2: Simulation cell used to model oxidation of $\alpha$-BN. B, N, and O atoms are shown in green, white, and red, respectively. The 5 nm-thick $\alpha$-BN film is supported by a frozen BN layer (omitted for clarity), and a 5 nm vacuum region above the film contains randomly distributed atomic oxygen to simulate an oxidative environment. Visualized using VESTA vesta.
• Figure 3: (a) Fraction of B–B bonds, (b) B–O bonds, (c) N–N bonds, and (d) N–O bonds as a function of temperature during oxidation of $\alpha$-BN films generated at different quench rates.
• Figure 4: Evaluation of hybridization states during oxidation for $\alpha$-BN films prepared at different quench rates. (a) $sp$ fraction. (b) $sp^2$ and $sp^3$ fractions.
• Figure 5: B/N atomic ratio versus temperature during oxidation for $\alpha$-BN films prepared at different quench rates.