Analysis of GaN-based light-emitting diodes degraded by generation of deep-level states

Jung, Eunjin; Kim, Hyunsoo

doi:10.1002/pssa.201330501

Cited by 2 publications

(2 citation statements)

References 33 publications

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“…The VRH model, depicted by the dashed-dotted lines in figure 4, can well describe the temperature dependence of the reverse current only for T < ∼ 240 K and biases ranging from -0.5 to -5 V. For higher negative biases, corresponding to higher electric fields in the depletion region, the discrepancy between experimental points and VRH model becomes larger and larger. The value of T 0 obtained from the fit of the data re-lated to a bias of -5 V, namely 1 × 10 5 K, is about one order of magnitude lower than the ones reported by Shan et al 17 and Jung et al 45 for planar (In,Ga)N/GaN LEDs. This would indicate the presence of a higher density of traps, N T , in the NW-LEDs than in the planar counterparts (in fact, N T ∝ D T ∝ 1/T 0 ), thus supporting the outcome obtained by the DLTS measurements.…”

Section: Analysis Of the I-t Characteristicscontrasting

confidence: 54%

A physical model for the reverse leakage current in (In,Ga)N/GaN light-emitting diodes based on nanowires

Musolino

Treeck

Tahraoui

et al. 2016

Journal of Applied Physics

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We investigated the origin of the high reverse leakage current in light emitting diodes (LEDs) based on (In,Ga)N/GaN nanowire (NW) ensembles grown by molecular beam epitaxy on Si substrates. To this end, capacitance deep level transient spectroscopy (DLTS) and temperature-dependent current-voltage (I-V) measurements were performed on a fully processed NW-LED. The DLTS measurements reveal the presence of two distinct electron traps with high concentrations in the depletion region of the p-i-n junction. These band gap states are located at energies of 570 ± 20 and 840 ± 30 meV below the conduction band minimum. The physical origin of these deep level states is discussed. The temperature-dependent I-V characteristics, acquired between 83 and 403 K, show that different conduction mechanisms cause the observed leakage current. On the basis of all these results, we developed a quantitative physical model for charge transport in the reverse bias regime. By taking into account the mutual interaction of variable range hopping and electron emission from Coulombic trap states, with the latter being described by phononassisted tunnelling and the Poole-Frenkel effect, we can model the experimental I-V curves in the entire range of temperatures with a consistent set of parameters. Our model should be applicable to planar GaN-based LEDs as well. Furthermore, possible approaches to decrease the leakage current in NW-LEDs are proposed. a) M. Musolino and D. van Treeck contributed equally to this work. b) Author to whom correspondence should be addressed. Electronic mail: treeck@pdi-berlin.de dependent current-voltage (I-V) measurements. On the basis of these data, we have developed a quantitative physical model able to describe the experimental I-V curves of NW-LEDs in the reverse bias regime for a wide range of temperatures. The assumptions made in this study should remain valid also for planar devices based on III-N heterostructures, thus making our model applicable also to conventional planar LEDs.The NW-LED structure employed in this work was grown by molecular beam epitaxy (MBE) on an AlN-buffered ndoped Si(111) substrate with the help of self-assembly processes. The active region of the NW-LED consists of four axial (In,Ga)N quantum wells (QWs) with an average In content of approximately 25%, separated by three GaN barriers. The last QW is immediately followed by a Mg-doped (Al,Ga)N electron blocking layer (EBL). The active region is embedded between two doped GaN segments designed such that an n-i-p diode doping profile is created. A schematic Si x O y n-Si(111) FIG. 1. (Color online) Schematic of the employed NW-LED structure. Note that the various dimensions are not to scale.

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Section: Analysis Of the I-t Characteristicscontrasting

confidence: 54%

A physical model for the reverse leakage current in (In,Ga)N/GaN light-emitting diodes based on nanowires

Musolino

Treeck

Tahraoui

et al. 2016

Journal of Applied Physics

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“…In addition, it would be also meaningful to address the reliability of the monolithic white LED because it is the critical factor for commercialization. According to our previous studies concerning the reliability of a commercial-grade white LED lamp, − the primary failure origins are the generation of a deep-level states (or defects) at the InGaN/GaN active regions and/or the degradation of packaging materials. These two degradation mechanisms are also found to strongly depend on the junction temperature of the LED chip, namely, optical degradation is a thermally activated process.…”

Section: Results and Discussionmentioning

confidence: 99%

Monolithic Inorganic ZnO/GaN Semiconductors Heterojunction White Light-Emitting Diodes

Jeong

Ryou

et al. 2018

ACS Appl. Mater. Interfaces

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Monolithic light-emitting diodes (LEDs) that can generate white color at the one-chip level without the wavelength conversion through packaged phosphors or chip integration for photon recycling are of particular importance to produce compact, cost-competitive, and smart lighting sources. In this study, monolithic white LEDs were developed based on ZnO/GaN semiconductor heterojunctions. The electroluminescence (EL) wavelength of the ZnO/GaN heterojunction could be tuned by a post-thermal annealing process, causing the generation of an interfacial GaO layer. Ultraviolet, violet-bluish, and greenish-yellow broad bands were observed from n-ZnO/p-GaN without an interfacial layer, whereas a strong greenish-yellow band emission was the only one observed from that with an interfacial layer. By controlled integration of ZnO/GaN heterojunctions with different postannealing conditions, monolithic white LED was demonstrated with color coordinates in the range (0.3534, 0.3710)-(0.4197, 0.4080) and color temperatures of 4778-3349 K in the Commission Internationale de l'Eclairage 1931 chromaticity diagram. Furthermore, the monolithic white LED produced approximately 2.1 times higher optical output power than a conventional ZnO/GaN heterojunction due to the carrier confinement effect at the GaO/n-ZnO interface.

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Analysis of GaN-based light-emitting diodes degraded by generation of deep-level states

Cited by 2 publications

References 33 publications

A physical model for the reverse leakage current in (In,Ga)N/GaN light-emitting diodes based on nanowires

A physical model for the reverse leakage current in (In,Ga)N/GaN light-emitting diodes based on nanowires

Monolithic Inorganic ZnO/GaN Semiconductors Heterojunction White Light-Emitting Diodes

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