We have successfully implemented green and red light-emitting diodes (LEDs) based on InGaN/GaN quantum dots (QDs) grown by controlling the process of the growth interruption method using metal organic vapor phase epitaxy (MOVPE). It is found that the three-step growth interruption method and the underlying InGaN/GaN superlattice structure are beneficial for achieving greater indium incorporation in InGaN QDs. As a result, green and red LEDs with electroluminescence (EL) peak energies of 2.28 eV at 20 mA and 1.70 eV at 80 mA, respectively, are demonstrated. The EL emission energy blue shift of the green QD LEDs is 140 meV as injection current increases from 5 to 50 mA, while that of the red LED is 70 meV as injection current increases from 75 to 100 mA.
InGaN/GaN multilayer quantum dot (QD) structure is a potential type of active regions for yellow-green light-emitting diodes (LEDs). The surface morphologies and crystalline quality of GaN barriers are critical to the uniformity of InGaN QD layers. While GaN barriers were grown in multi-QD layers, we used improved growth parameters by increasing the growth temperature and switching the carrier gas from N2 to H2 in the metal organic vapor phase epitaxy. As a result, a 10-layer InGaN/GaN QD LED is demonstrated successfully. The transmission electron microscopy image shows the uniform multilayer InGaN QDs clearly. As the injection current increases from 5 to 50 mA, the electroluminescence peak wavelength shifts from 574 to 537 nm.
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 88 A/cm2, 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.
High-indium-composition InGaN quantum dots (QDs) have been grown using a growth interruption method by metal organic vapor phase epitaxy. Effects of V/III ratio and temperature on the density, size, and formation mechanism of InGaN QDs by this method are investigated by atomic force microscopy and photoluminescence measurements. At a V/III ratio of 16600 and a temperature of 650 C, adatoms can migrate on the surface and combine with each other to form QDs to relax stress when growth is interrupted. A lower V/III ratio of 8300 can increase the migration capability of adatoms, and stress is relaxed by formation of dots when the first nominal InGaN layer is grown, which results in the lower density and higher indium composition of QDs after the second InGaN layer growth. Three-dimensional growth can be enhanced and the density of QDs increases at a temperature of 600 C. #
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.