Photon recycling light emitting diode

Claim 2

A photon recycling light emitting diode comprising: a substrate made of a semiconductor material; a plurality of active layers located on the substrate, wherein said active layers are made of a semiconductive material; each successive active layer from said substrate having an increased bandgap energy over the bandgap energy of the preceding active layer; a plurality of barrier layers alternately interspersed between said active layers, wherein said barrier layers are made of a semiconductor material; each successive barrier layer from said substrate having a substantially higher bandgap energy than the bandgap energy of adjacent active layers; a window layer located on the active layer furthest from said substrate, wherein said window layer is made of a semiconductor material of opposite conductivity type than the active and barrier layers; and said window layer having a bandgap energy higher than the bandgap energy of any of the active layers.

Claim 3

A diode as claimed in claim 1 wherein the active layers, barrier layers, and window layer are formed from a direct bandgap semiconductor material.

Claim 4

A diode as claimed in claim 2 wherein the direct bandgap semiconductor material is a variable bandgap material.

Claim 5

A diode as claimed in claim 3 wherein said variable bandgap material is GaAlAs.

Claim 6

A diode as claimed in claim 3 wherein said increased bandgap energy in said active and said barrier layers is due to an increased content of Al in the GaAlAs.

Claim 7

A photon recycling light emitting diode comprising: a substrate made of a semiconductor material; a plurality of active layers located on the substrate, wherein said active layers are made of a semiconductor material; each successive active layer from said substrate having an increased bandgap energy over the bandgap energy of the preceding active layer; each of said active layers having an energy well that has a lower bandgap energy than the active layer in which it is located, said well in each active layer having a higher bandgap energy than the bandgap energy in the adjacent well and also in an absorbing active layer closer to the substrate; a plurality of barrier layers alternately interspersed between said active layers, wherein said barrier layers are made of a semiconductor material; each successive barrier layer from said substrate having a substantially higher bandgap energy than the bandgap energy of adjacent active layers and; a window layer located on the active layer furthest from said substrate, and having a bandgap energy higher than the bandgap energy of any of the active layers, wherein said window layer is made of a semiconductor material.

Claim 8

A photon recycling light emitting diode comprising: a substrate made of a semiconductor material; a plurality of active layers located on the substrate, wherein said active layers are made of a semiconductor material; each successive active layer from said substrate having an increased bandgap energy over the bandgap energy of the preceding active layer; each of said active layers having an energy well that has a lower bandgap energy than the active layer in which it is located, said well in each active layer having a higher bandgap energy than the bandgap energy in the adjacent well and also in an absorbing active layer closer to the substrate; a plurality of barrier layers alternately interspersed between said active layers, wherein said barrier layers are made of a semiconductor material; each successive barrier layer from said substrate having a substantially higher bandgap energy than the bandgap energy of adjacent active layers and; a window layer located on the active layer furthest from said substrate, and having a bandgap energy higher than the bandgap energy of any of the active layers, wherein said window layer is made of a semiconductor material.

Claim 9

A diode as claimed in claim 5 wherein the active layers, wells, window layer and barrier layers are formed from a direct bandgap semiconductor material.

Claim 10

A diode as claimed in claim 6 wherein said direct bandgap semiconductor material is a variable bandgap material.

Claim 11

A diode as claimed in claim 8 wherein said variable bandgap material is GaAlAs.

Claim 12

A diode as claimed in claim 7 wherein said increased bandgap energy in said active layers, wells, and barrier layers is due to an increased content of Al in the GaAlAs.