Phosphor-free white-light light-emitting diode of weakly carrier-density-dependent spectrum with prestrained growth of InGaN/GaN quantum wells

The authors grew a white-light InGaN/GaN quantum-well (QW) light-emitting diode epitaxial structure with its electroluminescence spectrum close to the ideal condition in the Commission International de l'Eclairage chromaticity based on the prestrained metal-organic chemical vapor deposition technique. The prestrained growth leads to the efficient yellow emission from three InGaN/GaN QWs of increased indium incorporation. The color mixing for white light is implemented by adding a blue-emitting QW at the top of the yellow-emitting QWs. The blueshifts of the blue and yellow spectral peaks of the generated electroluminescence spectra are only 1.67 and 8 nm, respectively, when the injection current increases from 10 to 70 mA. Such small blueshifts imply that the piezoelectric fields in their QWs are significantly weaker than those previously reported. (c) 2007 American Institute of Physics.