Electron tube

An electron tube, comprising:

• a side tube;
• a faceplate provided at one end of the side tube and having a photocathode that emits electrons in response to incident light;
• a stem provided at the other end of the side tube, the stem and the faceplate defining a vacuum region, the stem having a bump connection portion on its surface;
• and
• a semiconductor device fixed to the stem at its vacuum side, the semiconductor device having a front surface positioned on the stem side and a back surface positioned of the faceplate side, the semiconductor device including an electron incidence part, for receiving electrons emitted from the photocathode, and a periphery part provided at an outer periphery of the electron incidence part, the electron incidence part having a thin plate shape whose thickness is smaller than that of the periphery part, the periphery part having a bump which protrudes from the front surface thereof, the bump being fixed to the bump connection portion, the bump forming a space between the front surface of the semiconductor device and the surface of the stem, a filling material with insulation property being filled partially in the space at the periphery part, thereby partially closing the space at the periphery part.