Field electron emitters are made from these materials: 3D materials, like in metals e.g. W, Mo and in metal compounds HfC3, W/C4, Co/C5, are applied as electron sources in transmission electron microscopes TEM, scanning electron microscopes SEM, and signal amplifier tubes. Technical applications longed for long lasting emitters, which are found using a 2D emitter Zr-O-W. Other 2D emitters are searched for field emitter flat panel screens, like coralline carbon, and sheet shaped C emitters. 1D emitters are found in carbon nanotubes, and in diamond with strings of conducting sp2 material in the sp3 matrix, and are employed in power tubes, or in SiO2 with nano-granular Si crystals. Also edge emitters are investigated as FED sources for FED-pixels. Electron beam induced deposition EBID, is a way to produce 0D electron gas materials as nano-granular compound materials. Experimental results with these materials are gained from field emission I/V-curves and electron conduction measurements e.g. Poole Frenkel-curves at varying temperature. Here characteristic energies for variable range hopping are obtained for Au/C material and for Pt/C material. The brightness beta of such sources is beta > 2 109 A/cm2 sr. An explanation for the extraordinary capability of several EBID materials is brought forward by arguing the geometry quantisation of electron energy levels in 0D-quantum dots. This is revealed from high voltage high resolution TEM images of free standing tips. Small crystal electron modes is described as paths of standing electron waves.