Epitaxial-transparent-substrate light emitting diodes with a primary emission peak at 590nm and a secondary peak at 560nm have been fabricated in the indium aluminum gallium phosphide (InAlGaP) system. The active layer consists of an undoped, compressively strained indium gallium phosphide (InGaP) quantum well on a transparent In0.22(Al0.2Ga0.8)0.78P/ ∇x[Inx(Al0.2Ga0.8)1-xP]/GaP virtual substrate. Theoretical modeling of this structure predicts an accessible wavelength range of approximately 540nm to 590nm (green to amber). Emission with a peak wavelength of 570nm has been observed via cathodoluminescence studies of undoped structures with a quantum well composition of In0.35Ga0.65P. Light emitting diodes have been fabricated utilizing simple top and bottom contacts. The highest LED power of 0.18µW per facet at 20mA was observed for a quantum well composition of In0.32Ga0.68P and a bulk threading dislocation density on the order of 7x10 6 cm -2 . The spectrum of this device was composed of two peaks: a weak peak at the predicted 560nm wavelength and a stronger peak at 590nm. Based upon superspots present in electron diffraction from the quantum well region, we believe that the observed spectrum is the result of emission from ordered and disordered domains in the active region. The same device structure grown with a bulk threading dislocation density on the order of 5x10 7 cm -2 exhibited an identical spectral shape with a reduced power of 0.08µW per facet at 20mA. For a quantum well composition of In0.37Ga0.63P and an overall threading dislocation density on the order of 5x10 7 cm -2 , a single peak wavelength of 588nm with a power of 0.06µW per facet at 20mA was observed. BACKGROUND Light emitting diode (LED) devices are a natural replacement for common incandescent lights and indicators. LEDs are efficient, intense, long-lived, and produce little heat. However, the ultimate goal of red-green-blue LED mixing for full-color and white applications has been hindered by the lack of an appropriate green light source. While intense red and blue LEDs are available, various materials issues have prevented the development of a similarly intense green source 1 . The same materials issues limit even more strongly the production of solid-state lasers at these wavelengths. We present a possible solution, based on the InAlGaP system, for laser and high-brightness LED devices operating in the wavelength range of 540nm to 590nm.
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