Wavelength shift of gallium nitride light emitting diode with p-down structure

Both the p-gallium nitride (GaN) on an n-light-emitting diode (LED) structure and the n-GaN on p-LED structure were fabricated by metal-organic vapor phase epitaxy on c axis sapphire substrate. The output spectra with different applied bias voltages were studied on these structures. The small amount of the wavelength shift under a forward bias condition in the proposed p-down LED structure was observed but not in the n-down LED structure. This phenomenon was characterized by the effective electric field in the well created from the built-in electric field and the applied electric field. This proposed p-down LED shows an opportunity in the application of wavelength shift-free optoelectronic devices.