Modeling the electrical characteristics of InGaN/GaN LED structures based on experimentally-measured defect characteristics

Roccato, Nicola; Piva, Francesco; Santi, Carlo De; Brescancin, Riccardo; Mukherjee, Kalparupa; Buffolo, Matteo; Haller, Camille; Carlin, J.-F.; Grandjean, N.; Vallone, Marco; Tibaldi, Alberto; Bertazzi, Francesco; Goano, Michele; Verzellesi, Giovanni; Meneghesso, Gaudenzio; Zanoni, Enrico; Meneghini, Matteo

doi:10.1088/1361-6463/ac16fd

Cited by 24 publications

(12 citation statements)

References 41 publications

(85 reference statements)

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“…These results suggested that the identified defects derive from the interaction between dislocations, or other point defects, and the TDs generating NRRCs. Similar results have been reported also in previous studies [ 17,74,75 ] where the same midgap level has been measured. It is worth noticing that the presence of In‐related defects does not influence negatively the emission only through the increase in SRH recombination, whose effects are more evident not only at low current injection levels, [ 76 ] but also through other processes that are more relevant in high current regime, like the defect‐assisted Auger recombination process that will be described in Section 4.2.…”

Section: Defects In Gan Ledssupporting

confidence: 92%

“…To mitigate this issue, a particular structure composed of an AlInN/GaN SL UL with very thin layers (e.g., 2.1/1.75 nm) has been proposed. [49,74,83] This structure grants a greater improvement in the efficiency, but a critical issue still remains because a considerable spontaneous polarization mismatch at the AlInN/GaN interfaces is generated. This leads to a negative fixed charge density which creates a barrier for electrons.…”

Section: Mitigation Strategiesmentioning

confidence: 99%

“…(Right) PCS measurement and relative fit to extract the optical activation energies of the traps in InGaN single quantum well (SQW) LEDs. Reproduced with permission [74]. Copyright 2021, IOP Publishing.…”

mentioning

confidence: 99%

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Defects and Reliability of GaN‐Based LEDs: Review and Perspectives

Buffolo

Caria

Piva

et al. 2022

Physica Status Solidi (a)

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Herein, the main factors and mechanisms that limit the reliability of gallium nitride (GaN)-based light-emitting diodes (LEDs) are reviewed. An overview of the defects characterization techniques most relevant for wide-bandgap diodes is provided first. Then, by introducing a catalogue of traps and deep levels in GaN and computer-aided simulations, it is shown which types of defects are more detrimental for the radiative efficiency of the devices. Gradual degradation mechanisms are analyzed in terms of their specific driving force: a separate analysis of recombination-enhanced processes, driven by nonradiative recombination and/or temperature-assisted processes, such as defects or impurity diffusion, is presented. The most common lifetime estimation methods and standards adopted for solid-state luminaires are also reported on. Finally, the paper concludes by examining which are the typical degradation and failure mechanisms exhibited by LEDs submitted to electrical overstress.

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Section: Defects In Gan Ledssupporting

confidence: 92%

Section: Mitigation Strategiesmentioning

confidence: 99%

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Defects and Reliability of GaN‐Based LEDs: Review and Perspectives

Buffolo

Caria

Piva

et al. 2022

Physica Status Solidi (a)

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“…In the non-illuminated current-voltage characteristic presented in Figure 3 (a), a significant increase in the forward current below the main diode turn-on is observed. The current increase in this voltage range confirms the increase in the amount of traps in the active region [11][12][13][14] : in particular considering the time dependence of the current at 1.25 V, presented in Figure 3 (b), the leakage current increased by two order of magnitude with respect to the initial value, and could be fitted with a power law with exponent ~ 0.494. This result suggests the presence of a 1D diffusion process, since diffusion mechanism presents a square-root dependence on time.…”

Section: Constant Optical Power Stresssupporting

confidence: 75%

Degradation of GaN-based InGaN-GaN MQWs solar cells caused by thermally-activated diffusion

Nicoletto

Caria²,

Santi

et al. 2023

Gallium Nitride Materials and Devices XVIII

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We investigate the degradation of high-periodicity GaN-based InGaN-GaN multiple quantum wells (MQWs) solar cells submitted to stress under high excitation intensity and high temperature; stress conditions are chosen to investigate cell behavior in a harsh scenario, such as wireless power transfer systems, space applications and concentrator harvesting systems. By examining the decrease in the short-circuit current and electroluminescence of these devices and the increase in the forward current at low bias, we suggest the presence of a thermally-activated diffusion process of impurities from the p-side of the device toward the active region. This process favors the increase in the Shockley-Read-Hall (SRH) recombination rate. By employing the van Opdorp and t'Hooft model, we analyzed the time-variation of non-radiative Shockley-Read-Hall lifetime during aging, extracting the diffusion coefficient of the defect involved in the degradation; we also extracted the related activation energy by an appropriate fitting of the degradation kinetics according to Fick's second law of diffusion. The obtained values suggest that degradation originates from the diffusion of hydrogen, whose severity depends also on the thickness of the p-GaN layer of these devices. The proposed analysis methods and the obtained results are useful for understanding the physics of multiple quantum wells (MQWs) solar cells during degradation. The results can be used to increase the performance and reliability in novel applications where these devices are proposed, such us additional layer in multi-junction (MJ) solar cells, and the application in harsh environments.

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“…Gallium nitride (GaN) is a fundamental semiconductor material that has been applied to light emitting diodes (LEDs), [1] laser diodes (LDs), [2] as well as high electron mobility transistors (HEMTs), [3] etc. Normally, GaN has a crystal structure of wurtzite, with C-plane (0001) as basal plane.…”

Section: Introductionmentioning

confidence: 99%

Characterization of the N-polar GaN film grown on C-plane sapphire and misoriented C-plane sapphire substrates by MOCVD

Hu¹,

Song²,

Su³

et al. 2022

Chinese Phys. B

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Gallium nitride (GaN) thin film of the nitrogen polarity (N-polar) was grown on C-plane sapphire and misoriented C-plane sapphire substrates respectively by metal-organic chemical vapor deposition (MOCVD). The misorientation angle is off-axis from C-plane toward M-plane of the substrates, and the angle is 2° and 4° respectively. The nitrogen polarity was confirmed by examining the images of the scanning electron microscope before and after the wet etching in potassium hydroxide (KOH) solution. The morphology was studied by the optical microscope and atomic force microscope. The crystalline quality was characterized by the X-ray diffraction. The lateral coherence length, the tilt angle, the vertical coherence length, and the vertical lattice-strain were acquired using the pseudo-Voigt function to fit the X-ray diffraction curves and then calculating with four empirical formulae. The lateral coherence length increases with the misorientation angle, because higher step density and shorter distance between adjacent steps can lead to larger lateral coherence length. The tilt angle increases with the misorientation angle, which means that the misoriented substrate can degrade the identity of crystal orientation of the N-polar GaN film. The vertical lattice-strain decreases with the misorientation angle. The vertical coherence length does not change a lot as the misorientation angle increases and this value of all samples is near to the nominal thickness of the N-polar GaN layer. This study helps to understand the influence of the misorientation angle of misoriented C-plane sapphire on the morphology, the crystalline quality, and the microstructure of N-polar GaN films.

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Modeling the electrical characteristics of InGaN/GaN LED structures based on experimentally-measured defect characteristics

Cited by 24 publications

References 41 publications

Defects and Reliability of GaN‐Based LEDs: Review and Perspectives

Defects and Reliability of GaN‐Based LEDs: Review and Perspectives

Degradation of GaN-based InGaN-GaN MQWs solar cells caused by thermally-activated diffusion

Characterization of the N-polar GaN film grown on C-plane sapphire and misoriented C-plane sapphire substrates by MOCVD

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