Abstract: A monolithic, multi-color semiconductor light emitting diode (LED) is formed with a multi-bandgap, multi-quantum well (MQW) active light emitting region which emits light at spaced-apart wavelength bands or regions ranging from UV to red. The MQW active light emitting region comprises a MQW layer stack including n quantum barriers which space apart n?1 quantum wells. Embodiments include those wherein the MQW layer stack includes quantum wells of at least two different bandgaps for emitting light of two different wavelengths, e.g., in the blue or green regions and in at least one other region, and the intensities of the emissions are adjusted to provide a preselected color of combined light emission, preferably white light.

Abstract: In one embodiment, a method of forming a multijunction solar cell having lattice mismatched layers and lattice-matched layers comprises growing a top subcell having a first band gap over a growth semiconductor substrate. A middle subcell having a second band gap is grown over the top subcell, and a lower subcell having a third band gap is grown over the middle subcell. The lower subcell is substantially lattice-mismatched with respect to the growth semiconductor substrate. The first band gap of the top subcell is larger than the second band gap of the middle subcell. The second band gap of the middle subcell is larger than the third band gap of the lower subcell. A support substrate is formed over the lower subcell, and the growth semiconductor substrate is removed. In various embodiments, the multijunction solar cell may further comprise additional lower subcells. A parting layer may also be provided between the growth substrate and the top subcell in certain embodiments.