Abstract: The present invention relates to an electron tube having a configuration which can maintain its operating stability for a long period of time. The electron tube comprises, at least, a field emitter which is made of diamond or a material mainly composed of diamond and has a surface terminated with hydrogen, and a sealed envelope for accommodating the diamond field emitter. Due to the hydrogen termination, the electron affinity of the diamond field emitter is set to a negative state. Also, hydrogen is enclosed within the sealed envelope. Due to this configuration, the hydrogen-terminated state of the diamond field emitter surface is stabilized, and the electron affinity of the diamond emitter is restrained from changing for a long period of time.

Abstract: Formed on a semiconductor substrate (10) is a first semiconductor layer (20; light absorbing layer) of p-type which has a first dopant concentration and generates an electron in response to light incident. Formed on the first semiconductor layer (20) is a second semiconductor layer (30; electron transfer layer) of p-type having a second dopant concentration lower than the first dopant concentration. A contact layer (50) forms a pn junction with the p-type second semiconductor layer (30). A surface electrode (80) is formed on and in ohmic contact with the contact layer (50). A third semiconductor layer (40; activation layer) is formed within an opening of the contact layer (50) on the surface of the second semiconductor layer (30). Embedded in the second semiconductor layer (30) is a semiconductor section (60; channel grid) having a third dopant concentration.

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: A photoelectric emission surface which is excellent in stability and reproducibility of photoelectric conversion characteristics and has a structure capable of obtaining a high photosensitivity is provided. A predetermined voltage is applied between an upper surface electrode and a lower surface electrode by a battery. Upon application of this voltage, a p-n junction formed between a contact layer and an electron emission layer is reversely biased. A depletion layer extends from the p-n junction into the photoelectric emission surface, and an electric field is formed in the electron emission layer and a light absorbing layer in a direction for accelerating photoelectrons. When incident light is absorbed in the light absorbing layer to excite photoelectrons, the photoelectrons are accelerated by the electric field toward the emission surface.

Abstract: A photoelectric emission surface which is excellent in stability and reproducibility of photoelectric conversion characteristics and has a structure capable of obtaining a high photosensitivity is provided. A predetermined voltage is applied between an upper surface electrode and a lower surface electrode by a battery. Upon application of this voltage, a p-n junction formed between a contact layer and an electron emission layer is reversely biased. A depletion layer extends from the p-n junction into the photoelectric emission surface, and an electric field is formed in the electron emission layer and a light absorbing layer in a direction for accelerating photoelectrons. When incident light is absorbed in the light absorbing layer to excite photoelectrons, the photoelectrons are accelerated by the electric field toward the emission surface.

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: A junction, such as a Schottky junction, is formed between a conductive electrode and a semiconductor. A bias voltage is applied between the conductive electrode and an outward-emission-side electrode formed on the semiconductor at the side opposite to the junction. Upon illumination, photoelectrons are internally emitted in the conductive electrode into the semiconductor, transported through the semiconductor, and emitted outward from the semiconductor surface, which has been so treated as to reduce the surface barrier height. The semiconductor is semi-insulating, or a p-n junction is formed therein.

Abstract: Disclosed is a new type of transparent GaAs photo electric layer formed on an optical window made of a GaP single crystal substrate via an Al.sub.x Ga.sub.(1-x) As buffer layer, in which a gradual-lattice-constant layer of quadruple Al.sub.x Ga.sub.(1-x) PyAs.sub.(1-y) compound crystal is formed between the GaP single crystal substrate and the Al.sub.x Ga.sub.(1-x) As buffer layer. The y content in the gradual-lattice-constant layer of quadruple Al.sub.x Ga.sub.(1-x) PyAs.sub.(1-y) compound crystal changes from 1 to 0 as deposition of the gradual-lattice-constant layer of quadruple Al.sub.x Ga.sub.(1-x) PyAs.sub.(1-y) compound crystal goes on while the x content can arbitrarily be selected in the range of 0 to 1.