Temperature dependence of the quantum efficiency of 4H-SiC-based Schottky photodiodes

Abstract

Using metal-semiconductor structures based on a pure epitaxial layer of n-4H-SiC (N _d− N _a=4×10¹⁵ cm⁻³), UV photodetectors were created with a maximum photosensitivity at 4.9 eV and a quantum efficiency up to 0.3 el/ph. The photosensitivity spectrum of the base structure is close to the spectrum of bactericidal action of the UV radiation. For photon energies in the 3.4–4.7 eV range, the quantum efficiency of the photoelectric conversion exhibits rapid growth with the temperature above 300 K, which is explained by the participation of photons in indirect interband transitions. This growth is not manifested when the photon energy is close to the threshold energy of direct optical transitions in the nondirect-bandgap semiconductor, which allows the threshold energy to be evaluated (∼4.9 eV).