The ultraviolet radiation detectors based on wide-bandgap Schottky barrier structures

Recently, much attention has been given to measure and control ultraviolet radiation (UVR) from the Sun and artificial sources. We present photodetectors based on different wide-bandgap surface-barrier structures, which exhibit linear photocurrent-radiant flux characteristics in the range 10(-2) -10(3)W/m(2) and can register different types of UVR. The use of light filter UFS-6 with GaP photodetector results in a spectral photosensitivity range corresponding to the Sun UV radiation if observed on Earth. The spectral sensitivity range of the photodetectors based on 4H-SiC is near the spectrum of relative effectiveness of various wavelengths in bactericidal UVR. The photosensitivity of the surface-barrier photodetectors based on wide-bandgap semiconductors exhibits the essential decline in the short-wavelength UVR region (5-6 eV), which is the region of intrinsic absorption of the semiconductor. We propose a hot exciton model, according to which the hot excitons can form in the process of the photoelectroconversion in the short-wavelength UVR region because of Brillouin zone structure peculiarities. Thus, photocarriers, forming hot excitons, do not take part in the next photoelectric conversion process and the quantum efficiency decreases. (C) 2002 Elsevier Science B.V. All rights reserved.