Effects of quantum-well indium content on deep defects and reliability of InGaN/GaN light-emitting diodes with under layer

Abstract

We investigate the density of defects and the degradation rate in InGaN light-emitting diodes having identical dislocation density and epitaxial structure, but different indium content in the quantum well (QW; 12%, 16%, 20%). Our results, based on combined steady-state photocapacitance, light-capacitance voltage, and degradation measurements indicate that: (a) the density of defects in the superlattice underlayer is identical for the three wafers, indicating good and reproducible growth conditions; (b) the density of defects within the active region of the devices shows a monotonic dependence on the indium content in the QWs. These results, consistent with previous studies on the topic, prove unequivocally the important role of indium in favoring the incorporation of point defects, further clarifying the possible mechanisms of defect formation, and give a quantitative assessment of the related effect; (c) in step-stress experiments, the degradation rate was found to be much stronger for devices having high indium content in the QW. This result can be explained by considering a decrease in injection efficiency due to the generation or transport of defects, or an increment in defect-assisted Auger recombination terms due to the propagation of defects.

Optimizing performance and energy consumption in GaN(n)/In x Ga 1- x N/GaN/AlGaN/GaN(p) light emitting diodes by quantum-well number and mole fraction

“…As shown in Figure 10b, the spectral power vs the wavelength characteristics are significantly influenced by the number of added wells. With addition of each QW, the spectral power decreases within the wavelength range 380 to 480 nm, as described earlier [43]. With 1, 2 and 3 wells, additional peaks can be observed in the wavelength range 420 to 440 nm [43] corresponding to the violet range.…”

“…With addition of each QW, the spectral power decreases within the wavelength range 380 to 480 nm, as described earlier [43]. With 1, 2 and 3 wells, additional peaks can be observed in the wavelength range 420 to 440 nm [43] corresponding to the violet range. With more QWs, there is a longer wavelength shifting toward the blue color in the range 460 to 480 nm [79].…”

“…An active zone, containing 6 quantum wells of InGaN, at 16% indium and 3 nm thickness, separated by 15 nm thick intrinsic layer GaN(i) barriers, is used. The two-layered InGaN/GaN(i) LED was described earlier [43]. A 45 nm thick electron blocking layer (EBL) of AlGaN(p), doped with 15% aluminium, as described earlier [44], is used here.…”

Impact of Generation and Relocation of Defects on Optical Degradation of Multi-Quantum-Well InGaN/GaN-Based Light-Emitting Diode

“…In particular, the increment of traps causes a decrease in the optical power ratio (Figure 10) due to the optical power decay of 405 nm QW. This could be explained by an enhancement of defects that act as NRRCs [5,36]. Moreover, the optical power of the 495 nm QW is affected by the presence of traps in QB1 and the 405 nm QW only for high trap densities (N t_sim = 10 17 cm −3 ) [16,37].…”

Defects in III-N LEDs: experimental identification and impact on electro-optical characteristics

“…The experimental data clearly indicate that the OP decay rate at high measuring injection levels is strictly dependent on In concentration within the well. A first explanation for this behavior considers the role of charge/defects generation and/or propagation in the reduction of the injection efficiency of the device 24 . Specifically, charged defects located in proximity of the QW can act as scattering centers or form potential barriers that can ultimately lower the capture rate from the QW.…”