COLD ELECTRON-EMISSION FROM ELECTROLUMINESCENT POROUS SILICON DIODES

It is demonstrated that electroluminescent porous silicon(PS) diodes operate as surface-emitting cold cathodes. The PS diode is composed of a semitransparent thin Au film, PS layer, n-type Si substrate and ohmic contact. When a sufficient positive bias voltage is applied to the Au contact in vacuum, the diode uniformly emits electrons as well as visible light. This cold emission is explained by the model that electrons are injected from the substrate, drifted by the field within the PS layer, and ejected as hot electrons through the thin Au film. This mode gives important insight for understanding the electroluminescence mechanism of PS, and shows the potential of PS devices not only for optoelectronic applications, but also for vacuum microelectronic ones.