Ultrafast Diamond Photodiodes for Vacuum Ultraviolet Imaging in Space-Based Applications

Abstract

Monitoring the vacuum ultraviolet (VUV) radiation from the Sun by spaceborne photodetectors is an indispensable and crucial approach in solar physics research and atmospheric photochemistry investigations. Diamond-based photodetectors are emerging as ideal candidates to replace traditional silicon-based detectors for high-selectivity and radiation hardness. Here, a vertical Schottky photodiode based on p-type high-quality single-crystal diamond is presented. By modulating the diamond surface band structure and band alignment, an ultra-short response time of only 15 ns, and a photo-to-dark current ratio greater than 10⁵ under the reverse bias are achieved. It is the first time to study the spectral response of the diamond photodiode in the range of 260 nm to as low as 120 nm under vacuum conditions, exhibiting an ideal selective responsivity and excellent imaging capability in the VUV range. This device holds promising prospects for coupling with optomechanical systems to enable a multidimensional detection of solar VUV radiation, including imaging and spectrum.