Laser Writing of Hexagonal Boron Nitride Patterns with Low Global Thermal Budget.

Direct integration of hexagonal boron nitride with temperature-sensitive substrates is constrained by the high global temperatures used in conventional growth. Here, we combine low-temperature deposition of an ammonia-borane-derived precursor on SiO2/Si (substrate temperature ≈ 70 °C) with spatially confined conversion by a focused 532-nm continuous-wave laser under ambient surroundings. Laser-written regions develop a persistent Raman band near 1370 cm-1 with a full width at half-maximum of 56.41 cm-1, and hyperspectral Raman imaging localizes this response to the irradiated sites. X-ray photoelectron spectroscopy shows dominant B-N bonding and a B/N atomic ratio of 1.24 after conversion. High-resolution transmission electron microscopy reveals short, curved layered fringes with a median spacing of 0.349 nm, while scanning transmission electron microscopy-energy-dispersive X-ray spectroscopy establish nanocrystalline order and spatially colocated B and N within an oxygen-bearing, heterogeneous material. This approach enables low-temperature integration of hexagonal boron nitride with temperature-sensitive electronic and photonic platforms.