Influence of anodization conditions of porous silicon on its morphology and emission characteristics

The porous silicon electron emitter was fabricated with a structure of metal/porous silicon/metal by electrochemical anodization, rapid thermal oxidation, and magnetron sputtering, for the field emission display applications. The impacts of the fabrication conditions, such as the anodization current density and time, oxidation temperature and time, etc., on the microstructures and the electron emission characteristics were evaluated with scanning electron microscopy (SEM). The results show that the anodization current density and time significantly affect the emission characteristics and microstructures of the porous silicon emitters. For instance, as the anodization current density increased, the thickness of the porous Si layer increased; and the longer the anodization time, the thicker the porous layers. Thicker porous Si layers resulted in a higher threshold voltage of the emitter, Vth. The emitter, made of porous Si with a pore diameter of 6~16 nm, a layer thickness of 11.06 μm, and biased at 30 V, has the maximum emission efficiency, η, of 7.5‰.