Abstract: The invention relates to a photocathode having a structure that permits a decrease in the radiant sensitivity at low temperatures is suppressed so that the S/N ratio is improved. In the photocathode, a light absorbing layer is formed on the upper layer of a substrate. An electron emitting layer is formed on the upper layer of the light absorbing layer. A contact layer having a striped-shape is formed on the upper layer of the electron emitting layer. A surface electrode composed of metal is formed on the surface of the contact layer. The interval between bars in the contact layer is adjusted so as to become 0.2 ?m or more but 2 ?m or less.

Abstract: The transmission secondary electron emitter according to the present invention comprises a secondary electron emitting layer 1 made of diamond or a material containing diamond as a main component, a supporting frame 21 reinforcing the mechanical strength of the secondary electron emitting layer 1, a first electrode 31 formed on the surface of incidence of the secondary electron emitting layer 1, and a second electrode 32 formed on the surface of emission of the secondary electron emitting layer 1. A voltage is applied between the surfaces of the incidence and the emission of the secondary electron emitting layer 1 to form an electric field in the secondary electron emitting layer 1.

Abstract: A semiconductor light-receiving device has a substrate including upper, middle and lower regions in its front side. A p-type layer on the lower region has a top surface including a portion on a level with the middle region. An electrode covers at least part of the boundary between the portion of the p-type layer and the middle region. An n-type layer on the p-type layer has a top surface including a portion on a level with the upper region. Another electrode covers at least part of the boundary between the portion of the n-type layer and the upper region.

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 Al0.3Ga0.7N layer with an Mg content concentration of not less than 2×1019 cm?3 but not more than 1×1020 cm?3, so that a solar-blind type semiconductor photocathode 1 with high quantum efficiency is obtained.

Abstract: Multilayer films 2 to 7 containing a light absorption layer 4 are formed on a GaAs substrate. After laminating the GaAs substrate 1 and a glass substrate 8 so that an uppermost surface film 7 of the multilayer film and the glass substrate 8 may come into contact with each other, by pressurizing between the GaAs substrate 1 and the glass substrate 8 and heating them together, both substrates 1 and 8 are fusion-bonded. Next, the GaAs substrate 1 and the buffer layer 2 are first removed, and then the etch stop layer 3 is removed. Then, while coming into contact with the light absorption layer 4, comb-type Schottky electrodes 10 and 11, which are mutually apart, are formed.

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.

Abstract: The present invention relates to a semiconductor chip and the like provided with a structure, which is applicable to a terahertz electromagnetic-wave device and capable of further reducing the life of the carriers. The semiconductor chip comprises a single crystal semiconductor substrate and a Group III-V compound semiconductor layer. The Group III-V compound semiconductor layer is characterized in that, in the vicinity of the surface, the concentration of Group V atoms is higher than the concentration of Group III atoms, and in that oxygen is included therein. In the Group III-V compound semiconductor layer, many As-clusters are deposited. It is known that the As-clusters function as a main factor for capturing the carriers; particularly, it is known that As-clusters near the upper surface of the Group III-V compound semiconductor layer contribute to the capture of carriers. Also, the Group III-V compound semiconductor layer includes oxygen; and due to this oxygen, a deep level is formed.

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: The invention relates to a photocathode and the like having such structure for holding a photocathode plate on a light transparent member with good reliability and workability. In the photocathode, claw portions of a holding member fixed to the light transparent member is pressed against the lower surface of a supporting plate so that a photocathode plate is sandwiched between the light transparent member and the supporting plate. Thus, the supporting plate is pressed against the photocathode plate, so that the photocathode plate is pressed against the light transparent plate by the supporting plate. This allows the photocathode plate to be held reliably by the light transparent member. This simple configuration further provides good workability in assembling.

Abstract: The invention relates to a photocathode having a structure that permits a decrease in the radiant sensitivity at low temperatures is suppressed so that the S/N ratio is improved. In the photocathode, a light absorbing layer is formed on the upper layer of a substrate. An electron emitting layer is formed on the upper layer of the light absorbing layer. A contact layer having a striped-shape is formed on the upper layer of the electron emitting layer. A surface electrode composed of metal is formed on the surface of the contact layer. The interval between bars in the contact layer is adjusted so as to become 0.2 &mgr;m or more but 2 &mgr;m or less.

Abstract: A semiconductor photocathode comprises a p+-type semiconductor substrate of GaSb, and a p−-type light absorbing layer of InAsSb. A p+-type hole blocking layer is formed between the substrate and the light absorbing layer having wider energy band gap than that of the light absorbing layer, the blocking layer being made of AlGaSb.

Abstract: In the case of a thick light-absorbing layer 2, a phenomenon of a decrease in the time resolution occurs. However, when the thickness of the light-absorbing layer 2 is limited, a portion of low electron concentration in one electron group is cut out, and hence overlap regions of adjacent electron concentration distributions decrease. Therefore, by shortening the transit time necessary for the passage of electrons, regions of overlapping electron distributions due to diffusion can also be suppressed. Furthermore, the strength of an electric field within a light-absorbing layer can be increased by thinning the light-absorbing layer. Therefore, the time resolution of infrared rays can be remarkably improved by a synergistic action of these effects. If it is assumed that the time resolution is 40 ps (picoseconds), for example, when the thickness of a light-absorbing layer is 1.3 &mgr;m which is nearly equal to the wavelength of infrared, then a possible time resolution is 7.5 ps when this thickness is 0.

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.

Abstract: This photocathode comprises: InP substrate 1; InAsx2P1−x2(0<x2<1) buffer layer 2; Inx1Ga1−x1As (1>x1>0.53) light-absorbing layer 3; InAsx3P1−x3 (0<x3<1) electron-emitting layer 4; InAsx3P1−x3 contact layer 5 formed on the electron-emitting layer 4; active layer 8 of an alkali metal or its oxide or fluoride formed on the exposed surface of electron-emitting layer 4; and electrodes 6 and 7.

Abstract: In the polycrystal diamond thin film in accordance with the present invention, the average particle size is at least 1.5 &mgr;m and, in a Raman spectrum obtained by Raman spectroscopy, a peak intensity near a wave number of 1580 cm−1 has a ratio of 0.2 or less with respect to a peak intensity near a wave number of 1335 cm−1. The photocathode and electron tube in accordance with the present invention comprise the polycrystal diamond thin film as a light-absorbing layer.

Abstract: This photocathode comprises: InP substrate 1; InAsx2P1−x2(0<x2<1) buffer layer 2; Inx1Ga1−x1As (1>x1>0.53) light-absorbing layer 3; InAsx3P1−x3 (0<x3<1) electron-emitting layer 4; InAsx3P1−x3 contact layer 5 formed on the electron-emitting layer 4; active layer 8 of an alkali metal or its oxide or fluoride formed on the exposed surface of electron-emitting layer 4; and electrodes 6 and 7.

Abstract: The present invention is to provide a method of using a photocathode including a laminated heterostructure of Group III-V semiconductors, which is constituted by a p-type light-absorbing layer formed on a p-type substrate and a p-type electron-emitting layer formed on the light-absorbing layer, a first electrode formed to have a rectifying function with respect to the electron-emitting layer, and a second electrode formed in ohmic contact with the substrate, wherein a voltage necessary and sufficient to form a potential gradient throughout the light-absorbing layer is applied between the first electrode and the second electrode, thereby accelerating photoelectrons excited in the light-absorbing layer which absorbs external incident light on the basis of an electric field formed in the light-absorbing layer and the electron-emitting layer and emitting the photoelectrons from the electron-emitting layer.

Abstract: This invention relates to a transmission type electron multiplier having a high secondary electron generation efficiency and having the structure capable of detecting positions of incidence of detected light, and also to an electron tube provided therewith. The electron tube comprises a closed container, an electron source, housed in the closed container, for emitting electrons into the closed container, an anode disposed so as to face the electron source, and a transmission type electron multiplier disposed between the electron source and the anode. Particularly, the transmission type electron multiplier comprises a thin film of diamond or a material containing a principal component of diamond, and a reinforcing member for reinforcing the thin film, the reinforcing member having an aperture for exposing a part of the thin film.

Abstract: A photocathode includes a first layer of polycrystalline diamond or a material mainly composed of polycrystalline diamond. The first layer of polycrystalline diamond may be terminated with hydrogen, or oxygen, and a second layer of an alkali metal or compound of an alkali metal, may be provided on the first layer of polycrystalline diamond whose surface is terminated with hydrogen or oxygen. The photocathode can be use for both reflection and transmission electron tubes and can yield a quantum efficiency higher than that in a monocrystal diamond thin film.