In ultraviolet calibration applications

specific broadband detectors capable of covering the UVA

UVB

and UVC bands are essential to achieve full-spectrum response without the need for filter changes

thereby providing critical support for establishing a unified

traceable ultraviolet radiation calibration system. This paper reports on a GaN broadband Schottky ultraviolet detector based on a vertical "NiAu/i-GaN/n-GaN/sapphire" structure. An independent microcontroller-based calibration system for the ultraviolet detector was developed. The detector exhibits dual-peak responsivity at 250 nm and 365 nm

with a peak responsivity of 0.12 A/W. The device demonstrates a dark current density of only 0.35 µA/cm² at 0 V bias and shows no hard breakdown even at -5 V

indicating effective surface passivation and isolation from the substrate. Under zero-bias operation

thermal noise dominates

yielding a measured R₀A product of 2.6×10² Ω·cm²

corresponding to a relative detection efficiency (D*) of approximately 1.5×10¹⁰ cm ·Hz

0.5

/W. This structure enables simultaneous monitoring of the solar-blind and UVA bands without requiring visible light filtering

making it suitable for applications such as broad-spectrum UV index monitoring

curing light feedback

and flame detection.