Enhanced Device Performance of GaInN-Based Green Light-Emitting Diode with Sputtered AlN Buffer Layer

Ishimoto, Seiji; Han, Dong‐Pyo; Yamamoto, Kengo; Mano, Ryoya; Kamiyama, Satoshi; Takeuchi, Tetsuya; Iwaya, Motoaki; Akasaki, Isamu

doi:10.3390/app9040788

Cited by 11 publications

(3 citation statements)

References 42 publications

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“…By increasing the concentration of indium inside the UL, the number of defects incorporated in the subsequent QW growth decreases [2]. These results are consistent also with reports by other groups [3][4][5][6][7][8][9][10][11][12][13][14], where the performance of GaN p-i-n diodes was improved via a similar approach. In addition to the concentration of indium, also thegrowth temperature can have a role in the reduction of the defects [15].…”

Section: Introductionsupporting

confidence: 90%

Defect incorporation in In-containing layers and quantum wells: experimental analysis via deep level profiling and optical spectroscopy

Piva

Santi

Caria

et al. 2020

J. Phys. D: Appl. Phys.

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Recent studies demonstrated that the performance of InGaN/GaN quantum well (QW) light emitting diodes (LEDs) can be significantly improved through the insertion of an InGaN underlayer (UL). The current working hypothesis is that the presence of the UL reduces the density of non-radiative recombination centers (NRCs) in the QW itself: during the growth of the UL, surface defects are effectively buried in the UL, without propagating towards the QW region. Despite the importance of this hypothesis, the concentration profile of defects in the quantum wells of LEDs with and without the UL was never investigated in detail. This paper uses combined capacitance-voltage and steady-state photocapacitance measurements to experimentally identify the defects acting as NRCs and to extract a depth-profile of the traps, thus proving the incorporation upon indium-reaction. Specifically: (i) we demonstrate that LEDs without UL have a high density (9.2 × 1015 cm−3) of defects, compared to samples with UL (0.8 × 1015 cm−3); (ii) defects are located near midgap (E C-1.8 eV, corresponding to E i-E T ∼ 0.3 eV), thus acting as efficient NRCs; (iii) crucially, the density of defects has a peak within the QWs, indicating that traps are segregated at the first grown InGaN layers; (iv) we propose a model to calculate trap distribution in the QW, and we demonstrate a good correspondence with experimental data. These results provide unambiguous demonstration of the role of UL in limiting the propagation of defects towards the QWs, and the first experimental characterization of the properties of the related traps.

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Section: Introductionsupporting

confidence: 90%

Defect incorporation in In-containing layers and quantum wells: experimental analysis via deep level profiling and optical spectroscopy

Piva

Santi

Caria

et al. 2020

J. Phys. D: Appl. Phys.

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“…The sapphire substrate was bonded onto the AlGaInP based red TFFC micro-LED to form the AlGaInP based red FC micro-LED [33]. The GaN based green/blue FC micro-LEDs structure comprised a metal layer, p-type GaN, a p-AlGaN electron blocking layer, InGaN/GaN multiple quantum wells, n-type GaN, and sapphire substrate [34][35][36][37][38]. Figure 2 shows the relationship between substrate thickness and the LEEs of each face of RGB micro-LEDs.…”

Section: Simulation Modelmentioning

confidence: 99%

Light Extraction Analysis of AlGaInP Based Red and GaN Based Blue/Green Flip-Chip Micro-LEDs Using the Monte Carlo Ray Tracing Method

et al. 2019

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Micro-scale light emitting diodes (micro-LEDs) commonly employ a thin-film flip-chip (TFFC) structure whose substrate is lifted off by an excimer laser. However, flip-chip (FC) micro-LEDs with a substrate can provide a sharp rise on sidewall emission by increasing the sidewall area. Here, we investigate the influence of substrate thickness, encapsulation, surface texture, microstructures between the substrate and epilayer, as well as the size, cutting shape, and angle of the chip on the light extraction efficiencies (LEEs) of FC micro-LEDs by using the Monte Carlo ray tracing method. We find that the LEE of the blue FC micro-LED chip increases by 46.5% over that of the blue TFFC micro-LED chip. After the encapsulation with the epoxy lens is applied, the LEEs of the blue TFFC micro-LED and blue FC micro-LED increase by 129% and 110.5%, respectively. The underlying mechanisms for the use of surface texture, patterned sapphire substrate, air-void array, and chip shaping technologies to improve the LEEs of FC micro-LEDs are also investigated in detail. We find that the LEEs AlGaInP based red FC micro-LED and GaN based blue/green FC micro-LEDs exhibit a sharp rise when the chip size drops from 30 to 10 µm. The inverted trapezoid FC micro-LED with patterned sapphire substrate (PSS) and encapsulation shows extraordinarily strong top emission and high collimation. We believe that our study offers a promising and practical route for obtaining high efficiency micro-LEDs.

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“…For MicroLEDs, even small wavelength fluctuations at the micron level may have a huge impact on yield and increase production costs. What's more, when applied to highresolution displays, the stability of LEDs is a major requirement under high temperature and various injection current [6], [7]. For the former one, the uniform distribution of indium is crucial, while for the latter one, it is closely related to the crystal quality.…”

Section: Introductionmentioning

confidence: 99%

Fabrication of High Efficiency Green InGaN/GaN MicroLEDs by Modulating Potential Barrier Height of the Sidewall MQWs in V-Pits

Liu,

Zhang,

Zhang

et al. 2024

IEEE Photonics J.

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In this study, Green MicroLEDs with different H2 flow during the barrier growth are investigated. We observe that the Indium composition near V-pits affects potential barrier height of the sidewall multiple quantum wells (MQWs) thus has strong impact on screening effect of V-pits. EQE and relative IQE has a dramatically increase with more hydrogen flow during barrier growth, and thermal endurance and wavelength stability was also improved. The enhancement has been confirmed to come from the reduction of non-radiative recombination centers from small V-pits and higher potential barrier height on sidewall MQWs in V-shaped pits which screen dislocations (TDs). These results demonstrate the advantages of modification H2 flow during barrier growth and also provide a new concept to modulate potential barrier height of the sidewall MQWs for better screening effect for further improvement on MicroLEDs performance.

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Enhanced Device Performance of GaInN-Based Green Light-Emitting Diode with Sputtered AlN Buffer Layer

Cited by 11 publications

References 42 publications

Defect incorporation in In-containing layers and quantum wells: experimental analysis via deep level profiling and optical spectroscopy

Defect incorporation in In-containing layers and quantum wells: experimental analysis via deep level profiling and optical spectroscopy

Light Extraction Analysis of AlGaInP Based Red and GaN Based Blue/Green Flip-Chip Micro-LEDs Using the Monte Carlo Ray Tracing Method

Fabrication of High Efficiency Green InGaN/GaN MicroLEDs by Modulating Potential Barrier Height of the Sidewall MQWs in V-Pits

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