Method of using photocathode and method of using electron tube

摘要

The present invention is to provide a method of using a photocathode including a laminated heterostructure of Group III - V semiconductors, which is ccnstituted by a p-type light-absorbing layer formed on a p-type substrate and a p-type electron-emitting layer formed on the light-absorbing layer, a first electrode formed to have a rectifying function with respect to the electron-emitting layer, and a second electrode formed in ohmic contact with the substrate, wherein a voltage necessary and sufficient to form a potential gradient throughout the light-absorbing layer is applied between the first electrode and the second electrode, thereby accelerating photoelectrons excited in the light-absorbing layer which absorbs external incident light on the basis of an electric field formed in the light-absorbing layer and the electron-emitting layer and emitting the photoelectrons from the electron-emitting layer. The accelerated electrons largely decrease differences in transit time until reaching the emission surface of the electron-emitting layer as compared to diffused electrons. Therefore, the response speed of the photocathode for detecting external incident light is increased. <IMAGE> <IMAGE>