The influence of random indium alloy fluctuations in indium gallium nitride quantum wells on the device behavior

Yang, Tsung-Jui; Shivaraman, Ravi; Speck, James S.; Wu, Yuh‐Renn

doi:10.1063/1.4896103

Cited by 134 publications

(114 citation statements)

References 42 publications

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“…The strong variations in the hole ground state energies in cplane systems are attributed to hole wave function localization effects due to random alloy fluctuations [28,29,35]. To confirm this behavior in a nonpolar system, Fig.…”

Section: Gs and Holementioning

confidence: 99%

“…Obviously, these approaches completely neglect wave function localization arising from effects that could be attributed to the microscopic alloy structure. Recently, continuum-based approaches have been modified to include random alloy fluctuations [27][28][29]. Even though such an approach captures some of the localization effects introduced by alloy fluctuations it cannot reveal the microscopic origin of localization effects, including in particular the presence of In-N-In-N chains as shown by density functional theory (DFT) [30,31].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Structural, electronic, and optical properties ofm-plane InGaN/GaN quantum wells: Insights from experiment and atomistic theory

Schulz¹,

Tanner

O’Reilly

et al. 2015

Phys. Rev. B

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In this paper we present a detailed analysis of the structural, electronic, and optical properties of an m-plane (In,Ga)N/GaN quantum well structure grown by metal organic vapor phase epitaxy. The sample has been structurally characterized by x-ray diffraction, scanning transmission electron microscopy, and 3D atom probe tomography. The optical properties of the sample have been studied by photoluminescence (PL), time-resolved PL spectroscopy, and polarized PL excitation spectroscopy. The PL spectrum consisted of a very broad PL line with a high degree of optical linear polarization. To understand the optical properties we have performed atomistic tight-binding calculations, and based on our initial atom probe tomography data, the model includes the effects of strain and built-in field variations arising from random alloy fluctuations. Furthermore, we included Coulomb effects in the calculations. Our microscopic theoretical description reveals strong hole wave function localization effects due to random alloy fluctuations, resulting in strong variations in ground state energies and consequently the corresponding transition energies. This is consistent with the experimentally observed broad PL peak. Furthermore, when including Coulomb contributions in the calculations we find strong exciton localization effects which explain the form of the PL decay transients. Additionally, the theoretical results confirm the experimentally observed high degree of optical linear polarization. Overall, the theoretical data are in very good agreement with the experimental findings, highlighting the strong impact of the microscopic alloy structure on the optoelectronic properties of these systems.

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Section: Gs and Holementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Structural, electronic, and optical properties ofm-plane InGaN/GaN quantum wells: Insights from experiment and atomistic theory

Schulz¹,

Tanner

O’Reilly

et al. 2015

Phys. Rev. B

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show abstract

“…[7][8][9] Regarding with our recent studies, the indium fluctuation incorporated into the simulation model is exceptionally fitting the experimental L-I-V curves by adopting more reasonable material parameters. 10,11 On the other hand, many researches have been reported that the inverted hexagonal V-shaped pit (V-pit) formation are considered to be induced by TDs, 12,13 where V-pits might be the key role to improve the device efficiency under such high dislocation densities. 14 The studies show that active regions in structures with the V-pit are composed of the normal lateral c-plane quantum wells (QWs) and inclined sidewall [1011] facet QWs, where the indium composition of lateral c-plane QWs is higher than that of inclined QWs.…”

Section: Introductionmentioning

confidence: 99%

3D numerical modeling of the carrier transport and radiative efficiency for InGaN/GaN light emitting diodes with V-shaped pits

Hsu

et al. 2016

AIP Advances

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In this paper, influence of a V-pit embedded inside the multiple quantum wells (MQWs) LED was studied. A fully three-dimensional stress-strain solver and Poisson-drift-diffusion solver are employed to study the current path, where the quantum efficiency and turn-on voltage will be discussed. Our results show that the hole current is not only from top into lateral quantum wells (QWs) but flowing through shallow sidewall QWs and then injecting into the deeper lateral QWs in V-pit structures, where the V-pit geometry provides more percolation length for holes to make the distribution uniform along lateral MQWs. The IQE behavior with different V-pit sizes, threading dislocation densities, and current densities were analyzed. Substantially, the variation of the quantum efficiency for different V-pit sizes is due to the trap-assisted nonradiative recombination, effective QW ratio, and ability of hole injections.

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“…[10][11][12][13]), which cannot genuinely account for hot carriers and generally also produces larger turnon voltages for MQW LEDs than observed experimentally. [14] Many reasons have been suggested to explain this discrepancy, including charge transport through indium fluctuations, [15] V-shaped pits, [16] tunneling through traps [17] or hot carrier transport. [18] At present it is, however, unclear if the discrepancy is of a physical origin or if it arises simply because the very foundations of the widely adopted DD model make it incapable of predicting the most essential device-level characteristics of LEDs.…”

Section: Doi: 101002/aelm201600494mentioning

confidence: 99%

On the Monte Carlo Description of Hot Carrier Effects and Device Characteristics of III‐N LEDs

Kivisaari

Sadi

et al. 2017

Adv Elect Materials

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of LED operation remain poorly understood, presenting an obvious bottleneck for further LED development and optimization. [5] For example, recent measurements have shown that III-N LEDs exhibit notable hot carrier distributions already close to the peak efficiency, [6][7][8][9] suggesting that hot carriers might have a more profound effect on the device characteristics than previously anticipated.To date, conventional LED simulations have mainly relied on the drift-diffusion (DD) model (see, e.g., refs. [10-13]), which cannot genuinely account for hot carriers and generally also produces larger turnon voltages for MQW LEDs than observed experimentally. [14] Many reasons have been suggested to explain this discrepancy, including charge transport through indium fluctuations, [15] V-shaped pits, [16] tunneling through traps [17] or hot carrier transport. [18] At present it is, however, unclear if the discrepancy is of a physical origin or if it arises simply because the very foundations of the widely adopted DD model make it incapable of predicting the most essential device-level characteristics of LEDs.The Monte Carlo (MC) method has been established as the standard tool to simulate hot-carrier effects in unipolar semiconductor devices such as transistors. Recently the MC method has also been expanded by Bertazzi et al. to simulate hot electron effects in GaN barriers of LEDs using full-band MC methods, [19] and ourselves, as we have recently developed a coupled Monte Carlo-drift-diffusion (MCDD) simulation method to investigate hot-electron effects in full III-N MQW LED structures. [20][21][22] More recently, we have also introduced a full MC model, [23] which can be used to carry out full MC simulations of both electrons and holes in a complete LED device. Nevertheless, the previous works have not yet provided a full analysis of the pertinent physics and differences between MC and DD. To provide more insight into the physics of MQW devices and to facilitate their further development, we now deploy our full MC simulator to answer the following questions:

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The influence of random indium alloy fluctuations in indium gallium nitride quantum wells on the device behavior

Cited by 134 publications

References 42 publications

Structural, electronic, and optical properties ofm-plane InGaN/GaN quantum wells: Insights from experiment and atomistic theory

Structural, electronic, and optical properties ofm-plane InGaN/GaN quantum wells: Insights from experiment and atomistic theory

3D numerical modeling of the carrier transport and radiative efficiency for InGaN/GaN light emitting diodes with V-shaped pits

On the Monte Carlo Description of Hot Carrier Effects and Device Characteristics of III‐N LEDs

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