Group III nitride LED with undoped cladding layer

A semiconductor structure for light emitting devices that can emit in the red to ultraviolet portion of the electromagnetic spectrum, said structure comprising:

• a first n-type layer of AlxInyGa1-x-yN, where 0≦x≦1 and 0≦y<1 and (x+y)≦1;
• a second n-type layer of AlxInyGa1-x-yN, where 0≦x<1 and 0≦y <1 and (x+y)≦1, wherein said second n-type layer is an undoped layer having a first surface and a second surface;
• an active layer of AlxInyGa1-x-yN, where 0≦x<1 and 0≦y≦1 and (x+y)≦1, wherein said active layer is n-type and is positioned between said first n-type layer and the first surface of said second n-type layer;
• and
• a p-type layer of a Group III nitride, wherein said second n-type layer is positioned between said p-type layer and said active layer;
• wherein said first and second n-type layers have respective bandgaps that are each larger than the bandgap of said active layer;
• and wherein at least one of said first layer and said second n-type layer is compositionally graded in steps from said first surface to said second surface.

A semiconductor structure for light emitting devices that can emit in the red to ultraviolet portion of the electromagnetic spectrum, said structure comprising:

• a first n-type layer of AlxInyGa1-x-yN, where 0≦x≦1 and 0≦y<1 and (x+y)≦1;
• a second n-type layer of AlxInyGa1-x-yN, where 0≦x≦1 and 0≦y<1 and (x+y)≦1, wherein said second n-type layer is undoped;
• an active layer of AlxInyGa1-x-yN, where 0≦x<1 and 0≦y≦1 and (x+y)≦1, wherein said active layer is n-type and is positioned between said first n-type layer and said second n-type layer;
• and
• a p-type superlattice formed of layers of Group III nitrides, wherein said second n-type layer is positioned between said p-type superlattice and said active layer.

A semiconductor structure for a light emitting device, comprising:

• a first Group III nitride layer comprising n-type AlxInyGa1-x-yN wherein 0≦x≦1 and 0≦y<1 and (x+y)≦1;
• a Group III nitride based active layer comprising a quantum well on the first Group III nitride layer;
• a second Group III nitride layer on the active layer opposite the first Group III nitride layer, the second Group III nitride layer comprising n-type AlxInyGa1-x-yN wherein 0≦x≦1 and 0≦y<1 and (x+y)≦1;
• and
• a third Group III nitride layer on the second Group III nitride layer opposite the active layer, the third Group III nitride layer comprising n-type AlxInyGa1-x-yN wherein 0≦x≦1 and 0≦y<1 and (x+y)≦1,
• wherein at least one of the first and second Group III nitride layers comprises aluminum.

A semiconductor structure for a light emitting device, comprising:

• a first Group III nitride layer comprising AlxInyGa1-x-yN wherein 0≦x≦1 and 0≦y<1 and (x+y)≦1;
• a Group III nitride based active layer comprising a quantum well on the first Group III nitride layer;
• a second Group III nitride layer comprising AlxInyGa1-x-yN wherein 0≦x≦1 and 0≦y<1 and (x+y)≦1 on the active layer opposite the first Group III nitride layer;
• a third Group III nitride layer comprising n-type AlxInyGa1-x-yN wherein 0≦x≦1 and 0≦y<1 and (x+y)≦1 on the second Group III nitride layer opposite the active layer;
• and
• a fourth Group III nitride layer comprising AlxInyGa1-x-yN wherein 0≦x≦1 and 0≦y<1 and (x+y)≦1 on the third Group III nitride layer opposite the second Group III nitride layer,
• wherein at least one of the first and second Group III nitride layers comprises aluminum, and wherein at least one of the second, third, and fourth Group III nitride layers is undoped.