| 摘要 |
PURPOSE:To enable stable measurement of a quantity of electron beams supplied for a long period of time or in a large quantity, by contacting closely the periphery of an aperture of a metallic case with the peripheral edge of a metallic electrode surrounding the electrode on an active region of a semiconductor substrate while causing them to have electric conductivity with each other. CONSTITUTION:An insulator layer 7 is provided on the surface of a semiconductor substrate 3 provided with a P-N junction diode such that the layer 7 surrounds an active region A. Metallic electrodes 8 each consisting of 8-a-8-c are formed to cover the surface of the layer 7 and the region A, while a biasing electrode 10 is formed on the underside of the substrate 3. This substrate 3 is bonded to a ceramic plate 4 and these are covered witn a metallic case 6 having a thickness sufficient to transmit electronic beams and provided, above the region A, with an aperture having an area equal to or slightly smaller than the region A. The peripheral lower face of the aperture 13 and the metallic electrode 8-a on the surface of the layer 7 are caused to have conductivity therebetween and contacted closely without any gap. Thereby, electrons dispersed backward in the region A are prevented from reaching the exposed surface of the layer 7 from between the electrode 8-a and the case 6. Accordingly, increase of leak current or the like is eliminated. |
