InGaN laser diodes (LDs) with composition-graded (CG) quantum barriers (QBs) are proposed and our study of them described. In the CG QB LDs, the indium content x in the In x Ga 1-x N QB was increased gradually along the growth direction. Their laser power-current-voltage performance curves, carrier concentrations, energy band diagrams, current distributions, electrostatic fields, and stimulated recombination rate in the active region were studied. It is shown that the laser power increases from 59.8 mW to 106.9 mW at 120 mA and the slope efficiency increases from 0.76 W A −1 to 1.27 W A −1 , when the conventional GaN QBs are replaced by the proposed CG QBs. The simulation results indicate that LDs with CG QBs performed better than LDs with conventional GaN QBs and InGaN QBs because the suppression of electron leakage is more efficient, as is hole injection and carrier-stimulated recombination in multiple quantum wells through the appropriate formation of polarization energy band structures.

InGaN light-emitting diodes (LEDs) with InGaN/GaN/InGaN triangular (IGIT) barriers were designed and investigated on a theoretical basis. The carrier concentration and radiative recombination rate distribution in multiple quantum wells, energy band diagrams, light output power-current-voltage performance curves, and internal quantum efficiency of the LEDs with IGIT barriers were studied. The simulations showed that the InGaN LEDs with IGIT barriers have higher output light power, lower turn-on voltage, and less efficiency droop than that of LEDs with conventional GaN and InGaN barriers. These improvements originate from the appropriately designed energy band diagram of the LEDs with IGIT barriers, which improves injection efficiency of holes and confinement of electrons.