Visible-blind ultraviolet photodetectors based on ZnMgBeSe Schottky barrier diodes

Planar geometry Schottky barrier photodiodes designed for visible-blind ultraviolet detection have been fabricated. They are based on ZnMgBeSe alloys grown by molecular-beam epitaxy. High crystalline quality is achieved, which leads to a high responsivity (0.17 A/W at 375 nm) and a sharp cutoff of more than three orders of magnitude. As attested by the linear variation of the photocurrent with the optical excitation, there is no internal gain mechanism. A detectivity of 2×1010 mHz1/2 W−1 is obtained showing that low-noise devices with high sensitivity have been fabricated.