Optimization for growth condition of ultrathin hexagonal boron nitride on dielectric substrates via LPCVD method

In this study, the direct and transfer-free synthesis of ultrathin hexagonal Boron Nitride (h BN) films on non-catalytic quartz substrates was investigated using the Low-Pressure Chemical Vapor Deposition (LPCVD) method. The effects of key growth parameters, including growth duration (15-90 min), precursor amount (50-200 mg), and precursor decomposition temperature (80-100°C), were systematically investigated to achieve high quality film growth. Spectroscopic characterization confirmed the formation of the h-BN phase, with Raman spectra exhibiting the characteristic E2g vibrational mode and FT-IR analysis showing the distinct B-N stretching and B-N-B bending bonds at 1370 and 800 cm-1, respectively. UV-Vis spectroscopy revealed high optical transparency (>95%) in the visible region, and Tauc plot analysis yielded an optical bandgap of 5.68 eV. This widening of the bandgap relative to bulk h-BN (~5.2 eV) provides quantitative evidence of the few-layer nature of the films due to the quantum confinement effect. The results demonstrate that the optimized LPCVD process allows for the precise control of h-BN synthesis on dielectric surfaces, eliminating the need for metal catalysts and complex transfer processes for optoelectronic applications.