Abstract: A UV sensor 1 comprises a container 5 in which the upper end opening of a metal side tube 2 is sealed with a front plate 3 composed of Kovar glass as an incident light window and the lower end opening is sealed with a base plate 4. The front plate 3 serving as an incident light window constitutes part of the wall of container 5 by sealing the upper end opening of the metal side tube 2. A pin-type photodiode 6 is disposed inside the container 5. The pin-type photodiode 6 comprises a photoabsorption layer 9 formed from InxGa(1-x)N (0<x<1) between an n-type contact layer 8 and a p-type contact layer 10.

Abstract: The present invention relates to an illuminant, etc., having a high response speed and a high luminous intensity. The illuminant comprises a substrate and a nitride semiconductor layer provided on one surface of the substrate. The nitride semiconductor layer emits fluorescence in response to incidence of electrons. At least part of the emitted fluorescence passes through the substrate, and then exits from the other surface of the substrate. Generation of the fluorescence is caused by incidence of electrons onto a quantum well structure of the nitride semiconductor layer and recombination of pairs of electrons and holes generated due to electron incidence, and the response speed of fluorescence generation is on the order of nanoseconds or less. Also, the luminous intensity of the fluorescence becomes equivalent to that of a conventional P47 fluorescent substance.

Abstract: Ultraviolet light incident from the side of a surface layer 5 passes through the surface layer 5 to reach an optical absorption layer 4. Light which reaches the optical absorption layer 4 is absorbed within the optical absorption layer 4, and photoelectrons are generated within the optical absorption layer 4. Photoelectrons diffuse within the optical absorption layer 4, and reach the interface between the optical absorption layer 4 and the surface layer 5. Because the energy band is curved in the vicinity of the interface between the optical absorption layer 4 and surface layer 5, the energy of the photoelectrons is larger than the electron affinity in the surface layer 5, and so photoelectrons are easily ejected to the outside. Here, the optical absorption layer 4 is formed from an Al0.3Ga0.