Light extraction from a semiconductor light-emitting device via chip shaping
AssigneeLumileds Lighting U.S., LLC
InventorsMichael R Krames, Fred A Kish, Jr., Tun S Tan
Life of this patent
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Abstract
The invention is a method for designing semiconductor light emitting devices such that the side surfaces (surfaces not parallel to the epitaxial layers) are formed at preferred angles relative to vertical (normal to the plane of the light-emitting active layer) to improve light extraction efficiency and increase total light output efficiency. Device designs are chosen to improve efficiency without resorting to excessive active area-yield loss due to shaping. As such, these designs are suitable for low-cost, high-volume manufacturing of semiconductor light-emitting devices with improved characteristics.
Claims18
A semiconductor light-emitting device with improved side light extraction efficiency comprising:
- a multi-layered heterostructure having a first side;
- a p-n junction, within the multi-layered heterostructure, that defines an active device area;
- ohmic contracts electrically connecting to the p-n junction;
- a primary transparent window, abutting the first side, having a top device area and a frustum, wherein at least ≧50% of the frustum is at an oblique angle with respect to the multi-layered heterostructure, wherein the top device area is greater than the active device area;
- and
- wherein the oblique angle is selected to increase the light escaping through the frustum.
A semiconductor light-emitting device with improved side light extraction efficiency comprising:
- a multi-layered heterostructure having a first side;
- a p-n junction, within the multi-layered heterostructure, that defines an active device area;
- ohmic contacts electrically connecting to the p-n junction;
- a primary transport window, abutting the first side, having a top device area and a frustum, wherein at least ≧50% of the frustum is at an oblique angle with respect to the multi-layered heterostructure, wherein the top device area is greater than the active device area;
- an area yield, wherein area yield is defined as the ratio of the active device area to the top device area;
- and
- wherein the oblique angle is selected to increase the light escaping through the frustum.
Dependencies are inferred from the claim text.