A principle of planar-type visible light emission is presented using ballistic electrons as excitation source. The device is composed of a semitransparent top electrode, a thin film of fluorescent material, a nanocrystalline porous silicon (nc-PS) layer, an n-type silicon wafer, and an ohmic back contact. When a positive dc voltage is applied to the top electrode with respect to the substrate, electrons injected into the nc-PS layer are accelerated via multiple-tunneling through interconnected silicon nanocrystallites, and reach the outer surface as energetic hot or quasiballistic electrons. They directly excite the fluorescent film, and then induce uniform visible luminescence. This solid-state light-emitting device, regarded as a “vacuum-less cathode-ray tube,” has many technological advantages over the conventional luminescent devices. It may lead to big innovations in the development of large-area thin flat-panel display and other electronic devices. © 2002 American Institute of Physics.