Monolithic GaP green-emitting LED matrix-addressable arrays

The fabrication and performance of matrix-addressable green-emitting monolithic light-emitting diode (LED) alphanumeric displays are described. Matrix addressability is achieved by p-n junction electrical isolation of n-type stripes of GaP in vapor-phase epitaxial n-epi/p-epi/n-substrate structures by a masked Zn diffusion. Each n-type stripe serves as the common cathode for the LED's in a given column, and with the assistance of a distributed ohmic contact, forms the column address. Light-emitting p-n junctions are formed in the isolated n-type stripes by a second masked Zn diffusion. Rows of LED anodes are electrically connected by thin-film metallization through vias in a glass insulating layer. This truly planar fabrication process potentially offers a marked reduction in the cost of matrix-addressable LED arrays. The transparency of nitrogen-free GaP to light generated at p-n junctions localized in a nitrogen-doped epitaxial layer permits displays of this type to be flip-chip bonded and viewed through the substrate.