Xu Yiqin

Performance improvement of blue InGaN light-emitting diodes with a specially designed n-AlGaN hole blocking layer

Blue InGaN light-emitting diodes (LEDs) with a conventional electron blocking layer (EBL), a common n-AlGaN hole blocking layer (HBL), and an n-AlGaN HBL with gradual Al composition are investigated numerically, which involves analyses of the carrier concentration in the active region, energy band diagram, electrostatic field, and internal quantum efficiency (IQE). The results indicate that LEDs with an n-AlGaN HBL with gradual Al composition exhibit better hole injection efficiency, lower electron leakage, and a smaller electrostatic field in the active region than LEDs with a conventional p-AlGaN EBL or a common n-AlGaN HBL. Meanwhile, the efficiency droop is alleviated when an n-AlGaN HBL with gradual Al composition is used.

The influence of AlGaN/GaN superlattices as electron blocking layers on the performance of blue InGaN light-emitting diodes

P-AlGaN/P-GaN superlattices are investigated in blue InGaN light-emitting diodes as electron blocking layers. The simulation results show that efficiency droop is markedly improved due to two reasons: (i) enhanced hole concentration and hole carrier transport efficiency in AlGaN/GaN superlattices, and (ii) enhanced blocking of electron overflow between multiple quantum-wells and AlGaN/GaN superlattices.

Performance enhancement of an InGaN light-emitting diode with an AlGaN/InGaN superlattice electron-blocking layer

The efficiency enhancement of an InGaN light-emitting diode (LED) with an AlGaN/InGaN superlattice (SL) electron-blocking layer (EBL) is studied numerically, which involves the light-current performance curve, internal quantum efficiency electrostatic field band wavefunction, energy band diagram carrier concentration, electron current density, and radiative recombination rate. The simulation results indicate that the LED with an AlGaN/InGaN SL EBL has better optical performance than the LED with a conventional rectangular AlGaN EBL or a normal AlGaN/GaN SL EBL because of the appropriately modified energy band diagram, which is favorable for the injection of holes and confinement of electrons. Additionally, the efficiency droop of the LED with an AlGaN/InGaN SL EBL is markedly improved by reducing the polarization field in the active region.