Abstract: The present invention relates to a photocathode having a structure for improving the quantum efficiency and sharpening the absorption edge characteristic on the long wavelength side within the wavelength range of incident light to improve the photosensitivity, and an electron tube having the same. The photocathode according to the present invention comprises at least a p-type GaAlN layer for absorbing incident light to excite photoelectrons, a p-type GaN layer which covers the second major surface of the p-type GaAlN layer, the second major surface opposing a first major surface that faces a substrate, and a surface layer provided to sandwich the p-type GaN layer with the p-type GaAlN layer and mainly containing an alkali metal or an alkali metal oxide.

Abstract: The present invention provides a photoemission device excellent in quantum efficiency of photoelectric conversion, a high-sensitive electron tube employing it, and a high-sensitive photodetecting apparatus. A photoemission device of the present invention is arranged to have a photon absorbing layer for absorbing incident photons to excite photoelectrons, an insulator layer layered on one surface of the photon absorbing layer, a lead electrode layered on the insulator layer, and a contact formed on the other surface of the photon absorbing layer to apply a predetermined polarity voltage between the lead electrode and the other surface of the photon absorbing layer, whereby the photoelectrons excited by the incident photons entering the photon absorbing layer and moving toward the one side are made to be emitted by an electric field formed between the lead electrode and the one surface by the predetermined polarity voltage.

Abstract: The present invention provides a photoemission device excellent in quantum efficiency of photoelectric conversion, a high-sensitive electron tube employing it, and a high-sensitive photodetecting apparatus. A photoemission device of the present invention is arranged to have a photon absorbing layer for absorbing incident photons to excite photoelectrons, an insulator layer layered on one surface of the photon absorbing layer, a lead electrode layered on the insulator layer, and a contact formed on the other surface of the photon absorbing layer to apply a predetermined polarity voltage between the lead electrode and the other surface of the photon absorbing layer, whereby the photoelectrons excited by the incident photons entering the photon absorbing layer and moving toward the one side are made to be emitted by an electric field formed between the lead electrode and the one surface by the predetermined polarity voltage.

Abstract: There is disclosed a photocathode comprising:a photoelectric conversion layer for internally exciting photoelectrons in response to incident photons; a semiconductor layer having a photoelectron emission surface for emitting the photoelectrons generated and accelerated in the photoelectric conversion layer from the photoelectron emission surface; an upper surface electrode formed on the photoelectron emission surface of the semiconductor layer; and a lower surface electrode formed on the semiconductor layer so that the lower surface electrode is opposite to the upper surface electrode through the semiconductor layer, the upper surface electrode being divided so as to provide a plurality of pixel electrodes which are electrically insulated from each other, the plurality of pixel electrodes being respectively connected to a plurarity of bias application wires.

Abstract: This invention relates to a semiconductor photo-electron-emitting device for emitting photoelectrons excited from the valence band to the conduction band by incident photons on a semiconductor layer. The device includes a Schottky electrode formed on the emitting surface on a surface of the semiconductor layer, and a conductor layer formed on a surface opposite to the emitting surface. A set bias voltage is applied between the Schottky electrode and the conductor layer to accelerate photoelectrons generated by the excitation of incident photons to the emitting surface and to transfer the accelerated photoelectrons from an energy band of a smaller effective mass to an energy band of a larger effective mass.