Multi-Junction LED
A light source and method for making the same are disclosed. The light source includes a substrate and a light emitting structure that is deposited on the substrate. A barrier divides the light emitting structure into first and second segments that are electrically isolated from one another. A serial connection electrode connects the first segment in series with the second segment. A first blocking diode between the light emitting structure and the substrate prevents current from flowing between the light emitting structure and the substrate when the light emitting structure is emitting light. The barrier extends through the light emitting structure into the first blocking diode.
1 . A method for fabricating a light source, said method comprising
depositing a transition layer comprising a semiconductor material of a first conductivity type on a substrate;
depositing a blocking diode layer of an opposite conductivity type on said transition layer;
depositing a light emitting structure on said blocking diode layer
generating a barrier that divides said light emitting structure into first and second segments; and
depositing a serial connection electrode that connects said first and second substrates in series, wherein said barrier extends through said light emitting structure into said first blocking diode layer, said blocking diode layer preventing current from flowing from said light emitting structure to said substrate when said light emitting structure is generating light.
2 . The method of claim 1 wherein said barrier is generated by etching a trench extending through said light emitting structure to said transition layer, but not to said substrate.
3 . The method of claim 2 wherein depositing said serial connection electrode comprises depositing an insulating layer in said trench, and depositing a layer of electrically conducting material in said trench over said insulating layer, said insulating layer preventing said layer of electrically conducting material from making direct contact with walls of said light emitting structure that are exposed in said trench.
4 . The method of claim 2 wherein said insulating layer underlies a portion of said serial connection electrode that overlies said light emitting structure.
5 . The method of claim 1 wherein said substrate semiconductor layer comprises a plurality of layers of said opposite conductivity type arranged such that said plurality of layers comprise a plurality of serially connected reverse-biased diodes when said light emitting structure generates light.