Effect of temperature on the characteristics of 4$H$-SiC UV photodetectors

The influence exerted by the carrier concentration in the range (1 – 50) $\times$ 10$^{14}$ cm$^{-3}$ in $n$-4$H$-SiC chemical-vapor deposited (CVD) epitaxial layers on the spectral characteristics of UV photodetectors with Cr Schottky barriers in the range of 200–400 nm is revealed and explained in terms of the photoconductivity theory. Schottky barriers with a Cr film thickness of 20 nm and diameter of 8 mm are formed by thermal evaporation in vacuum through masks. A noticeable effect of the carrier concentration in the CVD epitaxial layers on the spectral characteristics of photodetectors upon heating to 200$^{\circ}$C is also observed and accounted for by a difference between the generation-recombination processes. The irradiation of photodetectors with 15-MeV protons at a fluence of 4 $\times$ 10$^{12}$ cm$^{-2}$ and a temperature of 200$^{\circ}$C leads to an increase in the quantum efficiency as compared to samples irradiated in similar modes at 25$^{\circ}$C. This is indicative of an increase in the radiation hardness and service life of 4$H$-SiC devices at elevated temperatures.