A thin diamond electron beam amplifier. The illumination side of a thin diamond is illuminated by a seed electron beam creating electron-hole pairs in the diamond. A voltage potential provides an electric field between the illumination side of the diamond and an acceleration grid opposite the emission side of the diamond. Electrons released in the diamond are accelerated through the emission side of the diamond toward the acceleration grid creating an amplified electron beam. Preferred embodiments of the present invention are useful to provide flat panel displays and replacements for thermionic cathodes, cathode ray tubes, fast photodetectors and image intensifiers.