Operation of electroluminescent porous silicon diodes as surface-emitting cold cathodes

Cold electron emission properties of porous silicon (PS) electroluminescent diodes have been investigated as a function of the top metal electrode thickness, surface work function, and the thickness of PS layer. It is shown that the best thicknesses for Pt and Au electrodes are 50∼80 Å. The emission is enhanced by introducing an Al–Mg alloy electrode with a relatively low work function. Although the emission efficiency and the threshold voltage show definite dependencies on the thickness of PS layer, the Fowler–Nordheim plots show a linear behavior in every case. The maximum emission current density and efficiency obtained in this study are 10 μA cm −2 and 10 −3, respectively.