Schottky barrier detectors on GaN for visible–blind ultraviolet detection

We report on the fabrication and characterization of vertical geometry transparent Schottky barrier ultraviolet detectors based on n−/n+-GaN structures grown over sapphire substrates. Spectral responsivity measurements were made using illumination through the UV transparent Schottky barrier metal. A responsitivity as high as 0.18 A/W was measured for wavelengths shorter than the absorption edge of GaN. The detector speed was RC limited and the fall time was 118 ns. The 1/f noise is identified to be the main noise contribution. At 300 Hz, we measure the noise equivalent power at less than 4×10−9 W.