LED with improved injection efficiency
View Patent ↗A light emitting device and method for making the same is disclosed. The light-emitting device includes an active layer sandwiched between a p-type semiconductor layer and an n-type semiconductor layer. The active layer emits lights when holes from the p-type semiconductor layer combine with electrons from the n-type semiconductor layer therein. The active layer includes a number of sub-layers and has a plurality of pits in which the side surfaces of a plurality of the sub-layers are in contact with the p-type semiconductor material such that holes from the p-type semiconductor material are injected into those sub-layers through the exposed side surfaces without passing through another sub-layer. The pits can be formed by utilizing dislocations in the n-type semiconductor layer and etching the active layer using an etching atmosphere in the same chamber used to deposit the semiconductor layers without removing the partially fabricated device.
1. A light emitting device comprising: a p-type semiconductor layer comprising a p-type semiconductor material; an n-type semiconductor layer comprising an n-type semiconductor material; and an active layer sandwiched between said p-type and n-type semiconductor layers,
said active layer emitting light when holes from said p-type semiconductor layer combine with electrons from said n-type semiconductor layer therein, said active layer comprising a plurality of sub-layers, each of said plurality of sub-layers comprising a side surface and a top surface, said active layer having a plurality of pits in which side surfaces of said plurality of said sub-layers are in contact with said p-type semiconductor material such that holes from said p-type semiconductor material are injected into those sub-layers through said exposed side surfaces without passing through another sub-layer, and wherein the active layer is configured such that at least 10 percent of said holes are injected into said active layer through said side surfaces of said plurality of said sub-layers, wherein said pits are located on random dislocations in said n-type semiconductor material.
2. The light emitting device of claim 1 wherein said pits are characterized by a pit density, said pit density being between 10 7 cm −2 and 10 10 cm 2 .
3. The light emitting device of claim 1 wherein said p-type and n-type semiconductor layers comprise GaN family materials.