Study of carrier dynamics and radiative efficiency in InGaN/GaN LEDs with Monte Carlo method

Lu, I-Lin; Wu, Yuh‐Renn; Singh, Jasprit

doi:10.1002/pssc.201001054

Cited by 6 publications

(3 citation statements)

References 20 publications

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“…112,120,121 The prime requisite for a better understanding of experimental information is probably an improved description of carrier transport across the active region. Promising efforts are represented by momentum-resolved models 23,122 and analytic-band Monte Carlo (MC) transport simulations, 123 but the need for a full-band MC approach (FBMC, possibly integrated with microscopic models of radiative and nonradiative recombination processes) is apparent, especially after the recent debate following the proposed identification of Auger recombination as the dominant mechanism in droop from electron emission spectroscopy experiments, 124 where FBMC analysis has suggested that the LED structure under investigation was probably unsuitable to recover an Auger signature. 125 …”

Section: Discussionmentioning

confidence: 99%

Correlating electroluminescence characterization and physics-based models of InGaN/GaN LEDs: Pitfalls and open issues

et al. 2014

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Electroluminescence (EL) characterization of InGaN/GaN light-emitting diodes (LEDs), coupled with numerical device models of different sophistication, is routinely adopted not only to establish correlations between device efficiency and structural features, but also to make inferences about the loss mechanisms responsible for LED efficiency droop at high driving currents. The limits of this investigative approach are discussed here in a case study based on a comprehensive set of currentand temperature-dependent EL data from blue LEDs with low and high densities of threading dislocations (TDs). First, the effects limiting the applicability of simpler (closed-form and/or one-dimensional) classes of models are addressed, like lateral current crowding, vertical carrier distribution nonuniformity, and interband transition broadening. Then, the major sources of uncertainty affecting state-of-the-art numerical device simulation are reviewed and discussed, including (i) the approximations in the transport description through the multi-quantum-well active region, (ii) the alternative valence band parametrizations proposed to calculate the spontaneous emission rate, (iii) the difficulties in defining the Auger coefficients due to inadequacies in the microscopic quantum well description and the possible presence of extra, non-Auger high-current-density recombination mechanisms and/or Auger-induced leakage. In the case of the present LED structures, the application of three-dimensional numerical-simulation-based analysis to the EL data leads to an explanation of efficiency droop in terms of TD-related and Auger-like nonradiative losses, with a C coefficient in the 10−30 cm6/s range at room temperature, close to the larger theoretical calculations reported so far. However, a study of the combined effects of structural and model uncertainties suggests that the C values thus determined could be overestimated by about an order of magnitude. This preliminary attempt at uncertainty quantification confirms, beyond the present case, the need for an improved description of carrier transport and microscopic radiative and nonradiative recombination mechanisms in device-level LED numerical models

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Section: Discussionmentioning

confidence: 99%

Correlating electroluminescence characterization and physics-based models of InGaN/GaN LEDs: Pitfalls and open issues

et al. 2014

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“…To create a conclusive and quantitative link between the droop, Auger recombination in the QWs and the hot electron emission at the semiconductor surface, one needs fully microscopic device-level simulations of non-equilibrium transport in realistic III-N LEDs, in addition to reliable models for Auger recombination and other scattering rates. With the exception of microscopic models restricted to carrier dynamics within the QWs, 6 earlier simulations have relied heavily on quasi-equilibrium models, e.g., the drift-diffusion (DD) model, 7-11 which do not account for hot electrons at high input powers. To describe hot electrons and to maintain computational feasibility, we have combined the MC and DD methods.…”

mentioning

confidence: 99%

On the correlation of the Auger generated hot electron emission and efficiency droop in III-N light-emitting diodes

Sadi

Kivisaari

Oksanen

et al. 2014

Applied Physics Letters

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Recent experiments presented in by Iveland et al. [Phys. Rev. Lett. 110, 177406 (2013)] demonstrated that hot electron emission from cesiated p-contacts of III-nitride quantum-well (QW) light-emitting diodes (LEDs) coincides with the onset of the efficiency droop. We have carried out Monte Carlo simulations of hot-electron transport in realistic III-N LEDs. The simulations account for the hole population and all relevant electron scattering and recombination processes. We show that Auger recombination generates a significant hot electron population, which is temporarily trapped in the conduction band side-valleys, without decaying completely before reaching the pcontact. The leakage current due to electron overflow and thermal escape from the QWs is shown to have a minimal impact on the droop. We conclude that the experimentally observed hot electrons are created by Auger recombination in QWs, and that the Auger effect as the origin of the droop is the only consistent explanation for the experimental findings of Iveland et al., [

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“…However, the lattice mismatch between GaN and GaInN in conventional MQWs causes degradation of crystalline quality and the quantum-confined Stark effect (QCSE) . As the InN mole fraction of GaInN is increased, the above two effects become more pronounced. , In fact, it has been reported that the maximum internal quantum efficiency (IQE) in a planar (0001) plane LED with 10% InN mole fraction and a dislocation density of 10 8 cm –2 is approximately 60%, while the value decreases to 25% as the In composition increased to 20%. , Thus, GaInN-based LEDs have the problem of considerably low efficiency in the long-wavelength region . The second challenge is efficiency degradation caused by carrier overflow in the thin GaInN/GaN MQWs, and the structures with a thicker GaInN quantum well usually suffer from a tradeoff between preventing carrier overflow and suppressing QCSE.…”

Section: Introductionmentioning

confidence: 99%

Superlattice-Induced Variations in Morphological and Emission Properties of GaInN/GaN Multiquantum Nanowire-Based Micro-LEDs

Inaba

Ito

et al. 2022

ACS Appl. Mater. Interfaces

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Core−shell GaInN/GaN multiquantum shell (MQS) nanowires (NWs) are gaining great attention for high-efficiency microlight-emitting diodes (micro-LEDs) owing to the minimized etching region on their sidewall, nonpolar or semipolar emission planes, and ultralow density of dislocations. In this study, we evaluated the changes in NW morphologies and the corresponding device properties induced by GaInN/GaN superlattice (SL) structures. The cathodoluminescence intensities of the samples with 20 and 40 pairs of SLs were about 2.2 and 3.4 times higher, respectively, than that of the sample without SLs. The high-resolution scanning transmission electron microscopy (STEM) inspection confirmed that the high growth temperature of SLs prevented growth in the semipolar plane region close to the n-GaN core. A similar phenomenon was also observed for the GaN quantum barriers of the semipolar MQS region under a high growth temperature of 810 °C. This phenomenon was ascribed to the passivation of the semipolar plane surface by hydrogen atoms and the high probability of decomposition through NH 3 or N−H-related bonds. Although no clear SL grew on the semipolar plane near the n-core region, the top area of the nonpolar plane SL was expected to adequately suppress the point defects propagating from the n-GaN core to the semipolar plane MQS. The electroluminescence (EL) spectra and light output curves demonstrated a clear enhancement of more than 3-folds compared to the fabricated micro-LEDs without SL structures, which was associated with the improved crystalline quality of the MQS and enlarged area of the semipolar planes. Moreover, by increasing the growth time of GaN quantum barriers, the EL emission intensity of the micro-LED devices exhibited a 4-fold improvement owing to the reduced carrier overflow in the thickened GaN barriers on the semipolar (11̅ 01) planes. Thus, the results verified the possibility of realizing highly efficient NW-based micro-LEDs by optimizing the NW morphology using SL structures.

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Study of carrier dynamics and radiative efficiency in InGaN/GaN LEDs with Monte Carlo method

Cited by 6 publications

References 20 publications

Correlating electroluminescence characterization and physics-based models of InGaN/GaN LEDs: Pitfalls and open issues

Correlating electroluminescence characterization and physics-based models of InGaN/GaN LEDs: Pitfalls and open issues

On the correlation of the Auger generated hot electron emission and efficiency droop in III-N light-emitting diodes

Superlattice-Induced Variations in Morphological and Emission Properties of GaInN/GaN Multiquantum Nanowire-Based Micro-LEDs

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