Hamamatsu-photonics K.k.

Tomoko Mochizuki

Toru Hirohata

Minoru Niigaki

Masami Yamada

Hirofumi Kan

Kazutoshi Nakajima

Kuniyoshi Mori

A semiconductor photocathodeincludes: a transparent substrate; a first electrode, formed on the transparent substrateand enabling passage of light that has been transmitted through the transparent substrate; a window layer, formed on the first electrodeand formed of a semiconductor material with a thickness of no less than 10 nm and no more than 200 nm; a light absorbing layer, formed on the window layer, formed of a semiconductor material that is lattice matched to the window layer, is narrower in energy band gap than the window layer, and in which photoelectrons are excited in response to the incidence of light; an electron emission layer, formed on the light absorbing layer, formed of a semiconductor material that is lattice matched to the light absorbing layer, and emitting the photoelectrons excited in the light absorbing layerto the exterior from a surface; and a second electrode, formed on the electron emission layer.

Photocathode comprising a plurality of openings on an electron emission layer

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 &#x3bc;m or more but 2 &#x3bc;m or less.

Photocathode

Provided are a photocathode plate capable of stably achieving a high sensitive property, and an electron tube using such a photocathode plate. In a photomultiplier tube, an insulating layeris formed between a semiconductor electron emission layerin a photocathode plateA, and a first electrodeelectrically connected to an electron releasing portion. This insulating layerpermits the photocathode plateA to be cleaned by heat cleaning at a high temperature, in a stage before formation of an active layeron an exposed region of the semiconductor electron emission layerin the electron releasing portion. This makes it feasible to effectively clean the exposed region of the semiconductor electron emission layerin the electron releasing portionand to stabilize the physical properties of the exposed region. In consequence, a higher sensitive property can be stably achieved in the photocathode plateA and in the photomultiplier tubeusing the photocathode plateA.

Photocathode plate and electron tube

This photocathode comprises: InP substrate ; InAs P (0<x2<1) buffer layer ; In Ga As (1>x1>0.53) light-absorbing layer ; InAs P (0<x3<1) electron-emitting layer ; InAs P contact layer formed on the electron-emitting layer ; active layer of an alkali metal or its oxide or fluoride formed on the exposed surface of electron-emitting layer ; and electrodes and

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Hamamatsu, Japan

Tomoko Mochizuki