Analysis of below-threshold efficiency characteristics of InGaN-based blue laser diodes

Ryu, Han-Youl; Choi, Won Jun; Jeon, Ki-Seong; Kang, Min Ji; Choi, YoungRok; Lee, Jeong-Soo

doi:10.1063/1.4759247

Cited by 12 publications

(3 citation statements)

References 42 publications

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“…The Auger recombination coefficient deduced from a fit of the rate equation to the experimental photoluminescence (PL) data in an earlier effort is 1.4-2.0 × 10 −30 cm 6 /s for quasi-bulk InGaN layers [5]; however, the values extracted from EL measurements of LED structures vary by several orders of magnitude among different reports, 10 −32 -10 −24 cm 6 s −1 , the latter group of figures being some 3 orders of magnitude or more higher than the other reported values [1,5,6,[24][25][26][27]. From the analysis of the below-threshold efficiency of blue laser diodes (LDs), Ryu et al [28] have found the Auger recombination coefficient at high carrier densities to be ∼ 3 × 10 −31 cm 6 /s. Note that the direct Auger recombination coefficient decreases exponentially with the bandgap energy if the process involves transitions across the gap [20], which is supported by a fully microscopic many body model [20].…”

Section: Experimentally Determined and Calculated Auger Coefficient Cmentioning

confidence: 99%

“…From the analysis of the below-threshold efficiency of blue laser diodes (LDs), Ryu et al [28] have found the Auger recombination coefficient at high carrier densities to be ∼ 3 × 10 −31 cm 6 /s. Note that the direct Auger recombination coefficient decreases exponentially with the bandgap energy if the process involves transitions across the gap [20], which is supported by a fully microscopic many body model [20].…”

Section: Experimentally Determined and Calculated Auger Coefficient Cmentioning

confidence: 99%

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Saga of efficiency degradation at high injection in InGaN light emitting diodes

Avrutin¹,

Hafiz²,

Zhang³

et al. 2014

Turk J Phys

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Abstract:What has turned into highly complex and somewhat misunderstood efficiency loss mechanisms occurring in light-emitting diodes (LEDs) based on the InN-GaN material system at high injection levels are discussed. Suggestions are made as to the dominant mechanism(s) in an open forum format as well as pointing out some of the shortcomings of the methodologies used and premises forwarded. It is unequivocally known that increased junction temperature would cause a reduction in radiative power due to mainly the reduction in radiative recombination efficiency. Another obvious mechanism is the asymmetry in doping in wide bandgap semiconductors, such as GaN, wherein the hole concentration lags well behind that of electrons in the active region. Because an electron and a hole are required for radiative recombination, the radiative efficiency cannot keep up with increasing carrier injection due to progressively lagging hole population. This results in either electron escape without radiative recombination or electron accumulation, which in turn changes the internal bias of the device, manifested as reduced internal forward bias, which reduces the rate of increase in light intensity.Some of the reports ascribe the efficiency loss at high injection levels to Auger recombination (mainly through indirect and recently reportedly direct deductions) as the main and or the only source of efficiency loss by in many cases simply relying on the temperature and injection independent (not well taken) A, B, C coefficients to fit a third order polynomial to the efficiency vs. injection current. As for the direct deduction, the spectroscopic analysis of Auger kicked hot electrons as they traverse through the Γ and L bands before being emitted into the vacuum by means of cesiated surface challenges the existing theories and some experiments regarding carrier scattering and Γ -L separation. Despite just a few reports to the contrary, the bulk of the resonant optical emission experiments do not support the Auger argument as being the main cause. In parallel, there exists a body of theoretical and experimental reports for electron overflow of ballistic/quasi-ballistic electrons traversing the active region to p-GaN, escaping recombination altogether in the active region. In fact and from the get go, the LED industry ubiquitously employed, and continues to do so, an (Al,In)GaN electron-blocking layer (EBL) to prevent electron escape for improved light output that in and of itself would more than suggest that the electron escape (overflow) does indeed occur. The only adverse effect of EBL is * Correspondence: vavrutin@vcu.edu 269 AVRUTIN et al./Turk J Phys that it impedes hole injection due to the valence band offset between the p-type (Al,In)GaN EBL and p-GaN and also generates piezoelectric (if not lattice matched) and differential spontaneous polarization induced fields that pull down the conduction band edge at the interface reducing EBL's effectiveness. To at least reduce the aforementioned aggravating factors to some extent, the ele...

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Section: Experimentally Determined and Calculated Auger Coefficient Cmentioning

confidence: 99%

Section: Experimentally Determined and Calculated Auger Coefficient Cmentioning

confidence: 99%

Saga of efficiency degradation at high injection in InGaN light emitting diodes

Avrutin¹,

Hafiz²,

Zhang³

et al. 2014

Turk J Phys

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“…[5] Consequently, the threshold current density was reduced from 25 kA cm À2 (13.8 V) [4e] to 3.7 kA cm À2 (9.6 V), [4d] and a continuous-wave lasing was achieved at room temperature. [4d] Compared with the internal quantum efficiency (IQE) of blue LDs (76%) [6] and UV-A LDs (60%), [7] the IQE of UV-C LDs remains very low (2.3%). [3] The insufficient hole injection [8] is responsible for such low IQE, although the DPD technique circumvents the insufficient Mg activation in Al-rich AlGaN by inducing 3D hole gas.…”

Section: Introductionmentioning

confidence: 99%

Lasing Threshold Reduction of AlGaN‐Based Ultraviolet‐C Laser Diodes Using Strain Relaxed Lower Cladding Layer

Ren,

Liu,

Guo

et al. 2024

Physica Status Solidi (a)

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The dependence of the performance of ultraviolet‐C (UV‐C) laser diodes on the strain relaxation of lower cladding layer (LCL) is numerically investigated. As the strain relaxation increases from 0% to 100%, the threshold current density decreases from 25 to 12.7 kA cm−2, and the slope efficiency increases from 0.039 to 0.087 W A−1, thanks to an increase in internal quantum efficiency (IQE). The improvement of IQE is mainly due to the enhanced hole injection resulting from the increased hole concentration in the distributed polarization doping layers and the reduced hole blocking barrier height of the upper waveguide layer with increasing the strain relaxation. Additionally, the effective screening of the polarization field within the quantum well ameliorates the quantum‐confined Stark effect, further improving the IQE. Our study reveals that strain relaxed LCL is imperative to achieve low‐threshold UV‐C laser diodes.

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Epitaxial GaN Layers: Low Temperature Growth Using Laser Molecular Beam Epitaxy Technique and Characterizations

Kushvaha

Kumar

2016

Advances in Nanomaterials

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Analysis of below-threshold efficiency characteristics of InGaN-based blue laser diodes

Cited by 12 publications

References 42 publications

Saga of efficiency degradation at high injection in InGaN light emitting diodes

Saga of efficiency degradation at high injection in InGaN light emitting diodes

Lasing Threshold Reduction of AlGaN‐Based Ultraviolet‐C Laser Diodes Using Strain Relaxed Lower Cladding Layer

Epitaxial GaN Layers: Low Temperature Growth Using Laser Molecular Beam Epitaxy Technique and Characterizations

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