1：Experimental Design and Method Selection:

The study used radio frequency (r.f.) magnetron sputtering to deposit oBN thin films on graphite substrates, chosen for its ability to produce films with unique morphology under specific conditions. The method was selected based on previous work to achieve high-quality oBN films with reduced energy ion bombardment.

2：Sample Selection and Data Sources:

The sample was a graphite foil substrate, mechanically polished before deposition. Data were obtained from the deposited oBN films through various characterization techniques.

3：List of Experimental Equipment and Materials:

Equipment included an r.f. magnetron sputtering system (frequency 13.6 MHz, power 120 W), a hBN disk target (99.9% pure, diameter 60 mm), graphite substrate, vacuum chamber for deposition and FE measurements, SEM, AFM, TEM, XRD, and FTIR spectrometers. Materials included argon and nitrogen gases.

4：6 MHz, power 120 W), a hBN disk target (9% pure, diameter 60 mm), graphite substrate, vacuum chamber for deposition and FE measurements, SEM, AFM, TEM, XRD, and FTIR spectrometers. Materials included argon and nitrogen gases. Experimental Procedures and Operational Workflow:

4. Experimental Procedures and Operational Workflow: The deposition was carried out with a base pressure below 3 × 10?? Pa, substrate temperature of 450 °C, working pressure of 1.8 Pa, deposition time of 15 minutes, and gas mixture of 85% argon and 15% nitrogen. FE measurements were performed in a vacuum chamber at 2 × 10?? Pa using a diode configuration with a 150 μm gap between cathode (oBN film) and anode (conductive glass), with a sample area of 1 cm2.

5：8 Pa, deposition time of 15 minutes, and gas mixture of 85% argon and 15% nitrogen. FE measurements were performed in a vacuum chamber at 2 × 10?? Pa using a diode configuration with a 150 μm gap between cathode (oBN film) and anode (conductive glass), with a sample area of 1 cm2. Data Analysis Methods:

5. Data Analysis Methods: Data were analyzed using XRD for phase identification, FTIR for bonding analysis, SEM and AFM for morphology and roughness, TEM for internal structure, and J-E curves for FE properties with Fowler-Nordheim plots to interpret emission mechanisms.