FABRICATION OF A POROUS SILICON DIODE POSSESSING DISTINCT RED AND ORANGE ELECTROLUMINESCENT REGIONS

Porous silicon light emitting diodes with distinct red and orange elec troluminescent (EL) regions have been fabricated. Red luminescence is obtained by sonication of the as-formed orange-emitting porous silicon layers. While the red luminescence in the as-formed substrate is unst able in air or under irradiation, deposition of a thin layer of poly(9 -vinyl cabazole) (PVK) by spin-coating effectively circumvents the oxi dation process. The overall EL efficiency of the red and orange region s can be improved by depositing a thin film of a 1:1 (w/w) mixture of PVK and PBD [2-(4-biphenylyl)-5-(4-tert-butyl-phenyl)-1, 3, 4-oxadiazo le] on the porous Si surface.