According to a disclosed embodiment, an etch stop layer is fabricated on top of a base. An amorphous layer is then formed on top of the etch stop layer. An opening is then etched in the amorphous layer and the etch stop layer. The opening is etched with an opening width substantially equal to a critical dimension. The opening with opening width substantially equal to a critical dimension is then filled with a polycrystalline emitter. The resulting polycrystalline emitter has an emitter width substantially equal to the critical dimension. Moreover, a polycrystalline emitter structure can be fabricated, in which the critical dimension, i.e. the emitter width, is precisely controlled. The result is a polycrystalline emitter structure which is substantially as small as the resolution that the photolithography process would allow.