LED sidewall processing to mitigate non-radiative recombination
LEDs and methods of forming LEDs with various structural configurations to mitigate non-radiative recombination at the LED sidewalls are described. The various configurations described include combinations of LED sidewall surface diffusion with pillar structure, modulated doping profiles to form an n-p superlattice along the LED sidewalls, and selectively etched cladding layers to create entry points for shallow doping or regrowth layers.
1. A light emitting structure comprising:
a body including:
a first cladding layer doped with a first dopant type;
a barrier layer; and
an active layer between the first cladding layer and the barrier layer;
a pillar structure that protrudes from a first surface of the body, wherein the pillar structure includes a second cladding layer doped with a second dopant type opposite the first dopant type; and
a confinement region including a dopant concentration spanning sidewalls of the body and the first surface of the body, wherein the dopant concentration is formed of the second dopant type and encroaches from the sidewalls of the body toward a center vertical axis of the light emitting structure and from the first surface of the body toward the active layer, and the dopant concentration laterally encroaches toward a center vertical axis of the light emitting structure within the body past sidewalls of the pillar structure.
2. The light emitting structure of claim 1 , wherein the pillar structure protrudes from a surface of the barrier layer, the confinement region dopant concentration spans the surface of the barrier layer, and the dopant concentration encroaches laterally toward the center vertical axis within the barrier layer past the sidewalls of the pillar structure.
3. The light emitting structure of claim 1 , wherein the first dopant type is n-type, the second dopant type is p-type, and the dopant concentration is formed of a dopant selected from the group consisting of Mg and Zn.
4. The light emitting structure of claim 1 , further comprising:
a conformal passivation layer formed on and spanning the sidewalls of the body, the sidewalls of the pillar structure, and a surface of the pillar structure opposite the body;
an opening in the conformal passivation layer on the surface of the pillar structure; and
a conductive contact formed on the surface of the pillar structure and within the opening of the conformal passivation layer.
5. The light emitting structure of claim 1 , wherein the dopant concentration encroaches further toward the center vertical axis within the barrier layer than within the active layer and the first cladding layer.
6. The light emitting structure of claim 5 , further comprising a base including a first surface, wherein the body protrudes from the first surface of the base, and the first surface of the base is wider than the body.
7. The light emitting structure of claim 6 , wherein the dopant concentration spans the first surface of the base, and encroaches toward a second surface of the base opposite the first surface of the base.
8. The light emitting structure of claim 7 , further comprising a second conductive contact on the second surface of the base.
9. The light emitting structure of claim 8 , wherein the conductive contact is bonded to a contact pad on a display substrate with a solder material.
10. The light emitting structure of claim 1 , wherein the dopant concentration encroaches further toward the center vertical axis within the barrier layer and the active layer than within the first cladding layer.
11. The light emitting structure of claim 10 , further comprising a base including a first surface, wherein the body protrudes from the first surface of the base, and the first surface of the base is wider than the body.
12. The light emitting structure of claim 11 , wherein the dopant concentration spans the first surface of the base, and encroaches toward a second surface of the base opposite the first surface of the base.
13. The light emitting structure of claim 12 , further comprising a second conductive contact on the second surface of the base.
14. The light emitting structure of claim 13 , wherein the conductive contact is bonded to a contact pad on a display substrate with a solder material.