InGaN quantum dot green light-emitting diodes with negligible blue shift of electroluminescence peak wavelength

InGaN quantum dot (QD) light-emitting diodes (LEDs) were grown by metalorganic vapor phase epitaxy using an interruption method. As the injection current density increased from 2 to 88A/cm(2), the peak electroluminescence (EL) wavelength of the LED remained almost constant at around 527 nm. The negligible blue shift indicates that the quantum-confined Stark effect induced by piezoelectric polarization is suppressed well in InGaN QDs because of strain relaxation. Temperature-dependent EL spectra measurements indicate that the capture of electrons by QDs needs further improvement because of severe electron overflow to the p-type region. In addition, the peak EL wavelength is found to be abnormally longer than the photoluminescence wavelength. (C) 2014 The Japan Society of Applied Physics