For next generation spaceborne solar ultraviolet radiometers, innovative metal–semiconductor–metal (MSM) detectors based on wurtzite aluminum nitride (AlN) are being developed and characterized. A set of measurement campaigns and proton irradiation damage tests were carried out to obtain their ultraviolet-to-visible characterization and degradation mechanisms.
Our MSM is essentially two back-to-back Schottky barrier diodes with a single layer of undoped AlN grown on c-plane sapphire substrate (430 µm thick) from DOWA Electronics Materials Co. (Japan). The active area of the MSM detector has an inner diameter ranging from 1.1 to 4.3 mm on a 5 x 5 mm AlN.
In the wavelength range of interest, those detectors are reasonably sensitive and stable under brief irradiation with a negligible low dark current (3–6 pA/cm2). No significant degradation of the detector performance was observed after exposure to protons of 14.4 MeV energy, showing a good radiation tolerance up to fluences of 1E11 protons/cm2.
- MSM AlN, area = 1.1 mm (x6) diameter
- MSM AlN, area = 2 mm (x2) diameter
- MSM AlN, area = 3 mm diameter
- MSM AlN, area = 4.3 mm diameter