Segmented and quantum mechanically isolated active regions in light emitting diodes
LED devices and corresponding techniques for manufacturing LED devices are described. In some embodiments, an LED device includes a plurality of mesas, each mesa corresponding to a separate LED and including a layered semiconductor structure. The layered semiconductor structure includes an active region and a quantum barrier (QB) layer. The active region has a matrix of quantum well (QW) cells that are quantum mechanically isolated by the QB layer. In particular, the QB layer can include ridge-shaped structures that laterally separate adjacent QW cells. The matrix of QW cells can be arranged as a two-dimensional array. In some embodiments, the QW cells are epitaxially grown such that each QW cell is thicker along a central region and thinner along a peripheral region, with the peripheral region corresponding to where the QW cell meets a ridge-shaped structure of the QB layer.
1. A light emitting diode (LED) device comprising:
a plurality of mesas, each mesa of the plurality of mesas corresponding to a separate LED in the LED device and comprising a layered semiconductor structure that includes:
an active region including a two-dimensional (2D) array of quantum well (QW) cells, each QW cell including at least one quantum well configured to operate as a light-emitting region; and
a first quantum barrier (QB) layer that quantum mechanically isolates the QW cells of the 2D array from each other, wherein the first QB layer is continuous across both dimensions of the 2D array.
2. The LED device of claim 1 , wherein the LED device further comprises:
a p-contact; and
an n-contact, wherein the p-contact and the n-contact are shared by the QW cells in a first mesa of the plurality of mesas such that application of a voltage across the p-contact and the n-contact causes charge carriers to be injected into the QW cells in the first mesa concurrently.
3. The LED device of claim 1 , wherein the first QB layer comprises ridge-shaped nanostructures that separate adjacent QW cells in the 2D array.
4. The LED device of claim 3 , wherein:
the 2D array is epitaxially grown over the first QB layer; or
the first QB layer is epitaxially grown over the 2D array.
5. The LED device of claim 3 , wherein the nanostructures enclose a perimeter of each QW cell in the 2D array.
6. The LED device of claim 3 , wherein:
each QW cell comprises a central region and a peripheral region,
the peripheral region is adjacent to a nanostructure of the first QB layer, and
the peripheral region is thinner than the central region.
7. The LED device of claim 6 , wherein a bandgap of the at least one quantum well is wider along the peripheral region than along the central region.
8. The LED device of claim 3 , wherein each mesa further comprises a doped semiconductor layer formed on a surface of the first QB layer, the surface of the first QB layer being a substantially planar surface opposite to the active region.
9. The LED device of claim 8 , wherein the first QB layer comprises a material having a bandgap different from a bandgap of the doped semiconductor layer, and wherein the bandgap of the first QB layer is wider than a bandgap of the at least one quantum well.
10. The LED device of claim 1 , wherein each mesa further comprises a second QB layer formed on a surface of the active region opposite the first QB layer.
11. The LED device of claim 1 , wherein each QW cell comprises:
a first QW layer;
a second QW layer; and
a local QB layer between the first QW layer and the second QW layer.
12. The LED device of claim 11 , wherein the first QB layer is thicker than the local QB layer.