Polarization-matched GaInN∕AlGaInN multi-quantum-well light-emitting diodes with reduced efficiency droop

Abstract

Efficiency droop in InSb/AlInSb quantum-well light-emitting diodes Appl. Phys. Lett. 102, 011127 (2013); 10.1063/1.4773182Reduction in efficiency droop, forward voltage, ideality factor, and wavelength shift in polarization-matched GaInN/GaInN multi-quantum-well light-emitting diodes Blue multi-quantum-well light-emitting diodes ͑LEDs͒ with GaInN quantum wells and polarization-matched AlGaInN barriers are grown by metal-organic chemical vapor deposition. The use of quaternary alloys enables an independent control over interface polarization charges and bandgap and has been suggested as a method to reduce electron leakage from the active region, a carrier loss mechanism that can reduce efficiency at high injection currents-an effect known as the efficiency droop. The GaInN / AlGaInN LEDs show reduced forward voltage, reduced efficiency droop, and improved light-output power at large currents compared to conventional GaInN / GaN LEDs.

Influence of electron distribution on efficiency droop for GaN-based light emitting diodes

“…But for these applications, LEDs need to be operated at a current density below 10 A/cm 2 because of droop effect, which is still a key problem obstructing the development of high-power lighting-emitting diodes. Till now, lots of mechanisms have already been suggested to explain the "efficiency droop", such as polarization effect [1,2], electron leakage out of the active region [3,4], carrier delocalization [5], carrier injection efficiency [6], Auger recombination [7] and defects [5]. But the physical mechanisms of the droop effect aren't entirely clear and there is still a debate between them.…”

Solid-State Lighting Based on Light Emitting Diode Technology

“…high polarisation fields caused by the increasing strain with higher InN mole fractions. Possible mechanisms of 'efficiency droop' that have been proposed include Auger recombination [52,56], high defect density [54,58], carrier leakage [59], polarisation-induced built-in electric fields at hetero-interfaces [60,61], poor p-type conductivity [62,63] and carrier delocalisation at high current densities [64]. In order to reduce the current density and thus the efficiency droop, a thicker single quantum well has been proposed to replace thin multiple quantum wells as the active region [12].…”

Identification of nnp and npp Auger recombination as significant contributor to the efficiency droop in (GaIn)N quantum wells by visualization of hot carriers in photoluminescence

“…6,11 Nevertheless, the origin of the droop is still debated controversially. Other possible explanations, like recombination at dislocations 12 or electron leakage enhanced by high internal piezoelectric fields, [13][14][15][16] have also been suggested as the root cause for the drop in high current efficiency. Only recently, Iveland et al were able to provide evidence for Auger recombination in an electrically driven (GaIn)N based LED by detecting hot electrons.…”