Schottky barrier detectors on GaN for visible–blind ultraviolet detection

Abstract

We report on the fabrication and characterization of vertical geometry transparent Schottky barrier ultraviolet detectors based on $n^{-}{\mathrm{/n}}^{+}$ -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 $\text{1/f}$ noise is identified to be the main noise contribution. At 300 Hz, we measure the noise equivalent power at less than ${\text{4×10}}^{\text{−9}}$ W.