Design Criteria for Near-Ultraviolet GaN-Based Light-Emitting Diodes

Chiaria, Simone; Furno, Enrico; Goano, Michele; Bellotti, E.

doi:10.1109/ted.2009.2034792

Cited by 35 publications

(9 citation statements)

References 56 publications

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“…The order of magnitude of our A and C values is indeed in general agreement with several simulation studies discussing Auger effects on LED droop 3,4,23,24,47,107 and recent experimental studies on Auger recombination, focusing on its temperature 108 and composition 65,66 dependence and reaffirming the importance of Auger processes in the blue spectral range. Notably, the Augerlike coefficient determined in the present LED study is increasing with temperature, i.e.…”

Section: Auger Recombination and Auger-related Processessupporting

confidence: 91%

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: Auger Recombination and Auger-related Processessupporting

confidence: 91%

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

et al. 2014

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“…In our calculations, we considered direct capture processes from barrier bulk states to the ground state (GS) of a single QW with flat bands, neglecting possible transitions mediated by intermediate bound or quasi‐bound states. Electron eigenfunction profiles have been evaluated in the effective mass approximation, obtaining strain‐dependent energy gap and band offset according to (). Band bending and piezoelectric charge effects would surely led to more realistic modeling and could be considered without substantial modifications to the model.…”

Section: Model Validationmentioning

confidence: 99%

Model for carrier capture time through phonon emission in InGaN/GaN quantum wells

Vallone

Bertazzi

Goano

et al. 2015

Physica Status Solidi (b)

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A self‐energy‐based model for the calculation of the electron capture time through phonon emission in presence of carrier population is applied to nitride‐based quantum wells (QWs). The role of plasma dynamical screening on the Frölich interaction is investigated, highlighting its central role in the dependence of capture time on carrier density. The proposed approach yields a closed‐form expression for capture time as a function of the carrier densities in QW and barrier states. Its application to simple two‐population rate equations allows to reproduce available experimental data with excellent agreement, offering an accurate yet practical alternative to the usual approximation of a constant capture time in modeling light‐emitting diodes and lasers.

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“…Specifically, the unstrained bandgap energy of InN and GaN are 0.64 and 3.43 eV at 300 K, respectively [26]. The bowing parameter (b) of InGaN bandgap energy and band-offset ratio are set to be 2.1 eV and 0.67/0.33 [27], [28], respectively. The Caughey-Thomas approximation is employed for the mobility as a function of carrier density [29] …”

Section: Simulation Model and Parametersmentioning

confidence: 99%

Numerical Investigation of High-Efficiency InGaN-Based Multijunction Solar Cell

Chang

Yen

Chang

et al. 2013

IEEE Trans. Electron Devices

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A four-junction InGaN-based multijunction solar cell structure is proposed theoretically. The simulation results show that, with the use of appropriately designed compositional grading layers, the performance of InGaN-based multijunction solar cell can be maintained without the cost in performance degradation caused by the polarization-induced electric field and the potential barriers resulting from the heterointerfaces. After the optimization in thicknesses for current matching, a high conversion efficiency of 46.45% can be achieved under 1000-sun AM1.5D illumination, in which the short-circuit current density, open-circuit voltage, and fill factor are 12.2 × 10 3 mA/cm 2 , 4.18 V, and 0.77, respectively. The simulation results suggest that, in addition to the detrimental effects caused by the built-in electric polarization and potential barriers, the issue of crystalline quality is another critical factor influencing the performance of multijunction solar cells.

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Design Criteria for Near-Ultraviolet GaN-Based Light-Emitting Diodes

Cited by 35 publications

References 56 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

Model for carrier capture time through phonon emission in InGaN/GaN quantum wells

Numerical Investigation of High-Efficiency InGaN-Based Multijunction Solar Cell

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