PURPOSE: To largely improve energy resolution by disposing a carrier multiplication layer obtained by epitaxial growth and a breakdown voltage control layer of dopant concentration higher than the former on a semiconductor element opposite to a photocathode.
CONSTITUTION: A photocathode 40 for producing photoelectrons due to photons, a semiconductor element 66 for multiplying photoelectrons, opposite to it, and electron lenses 80 converging photoelectrons are disposed in a high-vacuum vessel comprising an enclosure 20, a light incident window 30 and a stem 50. In a photomultiplier tube 10, as above, a carrier multiplication layer 62 with dopant obtained by epitaxial growth being uniformly distributed is disposed on a semiconductor substrate 61 of a semiconductor element 60. A breakdown voltage control layer 64 of dopant concentration higher than the former is disposed on the layer. A photoelectron receiving portions 65 is partly exposed by means of an insulating layer 67 and an ohmic electrode layer 68. Accordingly, uniformity in avalanche multiplication gain for photoelectrons is attached and energy resolution is largely raised, so that high sensitive and quantitative measurement of-faint light becomes possible.
MURAMATSU MASAHARU
OISHI MAKOTO
ISHIKAWA YOSHITAKA
YAMAMOTO AKINAGA
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