A phototube suitable for detecting a photon, comprising: an electron ejector configured for emitting electrons in response to an incident photon; a detector configured for collecting the electrons and providing an output signal representative of the incident photon; an electrode configured for applying a voltage to drive the electrons to the detector; and one or more sidewalls forming an envelope of a hole between the electrode and the detector, wherein the electron ejector is inside the hole and bonded to the electrode.