Abstract: A photocathode includes a first layer having a first energy band gap for providing absorption of light of wavelengths shorter than or equal to a first wavelength, a second layer having a second energy band gap for providing transmission of light of wavelengths longer than the first wavelength, and a third layer having a third energy band gap for providing absorption of light of wavelengths between the first wavelength and a second wavelength. The first wavelength is shorter than the second wavelength. The first, second and third layers are positioned in sequence between input and output sides of the photocathode.

Abstract: A photocathode includes a first layer having a first energy band gap for providing absorption of light of wavelengths shorter than or equal to a first wavelength, a second layer having a second energy band gap for providing transmission of light of wavelengths longer than the first wavelength, and a third layer having a third energy band gap for providing absorption of light of wavelengths between the first wavelength and a second wavelength. The first wavelength is shorter than the second wavelength. The first, second and third layers are positioned in sequence between input and output sides of the photocathode.

Abstract: A method of manufacturing a photocathode includes forming a seed layer with a single crystal structure on a faceplate; forming a window layer over the seed layer; and forming an active layer over the window layer. The method can also include the step of cleaning the faceplate before the seed layer is formed. The steps of cleaning the faceplate, forming the seed layer, forming the window layer and forming the active layer are performed in an organometallic chemical vapor deposition reactor system. The seed layer is formed by depositing a buffer layer on the faceplate and annealing the buffer layer to form the seed layer having. The atmosphere during the annealing of the buffer layer includes hydrogen, arsine, trimethylaluminum, and trimethylgallium. A photocathode formed from the method is also disclosed.

Abstract: A gas collector is disclosed for use with epitaxial reactors. The gas collector is in the form of a base and top portion that are interconnected by means of a sealing arrangement. The top portion is configured to cover the base and define a conduit therebetween. Inlets and outlets are provided to direct chemical vapors from a reaction chamber of the epitaxial reactor into the conduit and further into an exhaust pipe of the epitaxial reactor. The gas collector is capable of forming a hermetic seal with the lid of the reaction chamber in order to prevent escape of chemical vapors.

Abstract: A fixture for centering and holding an elastomeric O-ring in position between vacuum sealing flanges during assembly and use thereof, having an annular body defining an outer surface and O-ring holding flange disposed on the outer surface for holding an elastomeric O-ring. The outer surface of the annular body defines a pair of beveled surfaces which enable the fixture to be inserted between the vacuum sealing flanges during assembly thereof without any substantial binding. The annular body of the fixture also defines a cylindrical inner surface having a diameter which is substantially identical to the diameter of the cylindrical inner surfaces of the sealing flanges to substantially prevent turbulent gas flow effects.

Abstract: A gas collector is disclosed for use with epitaxial reactors. The gas collector is in the form of a base and top portion that are interconnected by means of a sealing arrangement. The top portion is configured to cover the base and define a conduit therebetween. Inlets and outlets are provided to direct chemical vapors from a reaction chamber of the epitaxial reactor into the conduit and further into an exhaust pipe of the epitaxial reactor. The gas collector is capable of forming a hermetic seal with the lid of the reaction chamber in order to prevent escape of chemical vapors.