Inverted LED structure with improved light extraction
View Patent ↗A light source and method for fabricating the same are disclosed. The light source includes a substrate and a light emitting structure. The substrate has a first surface and a second surface, the second surface including a curved, convex surface with respect to the first surface of the substrate. The light emitting structure includes a first layer of a material of a first conductivity type overlying the first surface, an active layer overlying the first layer, the active layer generating light when holes and electrons recombine therein, and a second layer includes a material of a second conductivity type overlying the active layer and a second surface opposite to the first surface. A mirror layer overlies the light emitting structure.
1. A device comprising:
a substrate having a first surface and a second surface, said second surface comprising a curved, convex surface with respect to said first surface of said substrate;
a first layer overlying said first surface, said first layer comprising a material of a first conductivity type;
an active layer overlying said first layer, said active layer generating light when holes and electrons recombine therein; and
a second layer comprising a material of a second conductivity type, said second layer having a first surface overlying said active layer and a second surface opposite to said first surface, said substrate being transparent to light generated by said active layer.
2. The device of claim 1 wherein said first layer, said second layer, and said active layer comprise materials from the GaN family of materials.
3. The device of claim 1 wherein said substrate comprises sapphire.
4. The device of claim 1 wherein said curved convex surface is chosen such that a light ray generated in said active layer that is initially reflected from said surface due to internal reflection subsequently strikes said surface at an angle that is less than the critical angle to said surface at that point on said surface.
5. The device of claim 1 wherein said curved convex surface is non-spherical.
6. The device of claim 1 wherein said curved convex surface is substantially parabolic.