Suppression of efficiency droop in AlGaN based deep UV LEDs using double side graded electron blocking layer

Mondal, Ramit Kumar; Chatterjee, Vijay; Prasad, S.; Pal, Saurabh

doi:10.1088/1361-6641/ab7ce6

Cited by 18 publications

(9 citation statements)

References 36 publications

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“…The DUV-LED has been very useful in various applications such as sterilization [3], indoor growing plant [4,5], and disinfectant of virus [6]. However, there are factors affecting the performance of the DUV-LED such as the accumulation and distribution of carrier concentration in the active region [7], the design of the epitaxy layer [8] and the extra layer to facilitate the carrier transportation, such as the electron blocking layer (EBL) [9][10][11] and hole blocking layer (HBL) [10]. In general, the performance measurements of the LEDs are based on quantum efficiency and photoluminescence (PL); hence, these efforts focused on improving these qualities.…”

Section: Introductionmentioning

confidence: 99%

High photoluminescence intensity of heterostructure AlGaN-based DUV-LED through uniform carrier distribution

Aman¹,

Fajri²,

Noorden³

et al. 2022

Phys. Scr.

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We report a numerical analysis of the variation of Aluminium (Al) composition in Al Gallium Nitride (AlGaN)-based Deep-Ultraviolet Light-Emitting Diode (DUV-LED) and its effects on the carrier concentration, radiative recombination, and photoluminescence (PL). Three different structures with different Al compositions are compared and analyzed. The radiative recombination of the DUV-LED is less efficient due to the imbalance of carrier distribution. The findings show that the uniform electrons and holes distribution significantly improve the radiative recombination for structure with a thin step-shaped quantum well (QW). The simulated structure emits a wavelength of 302.874 nm, categorized in the ultraviolet-B (UV-B) spectrum. Our results imply that carrier uniformity in QW is required to enhance the light intensity of DUV-LED. Remarkably, the uniformity enhances the PL intensity drastically, at least six times higher than the first structure and twice higher than the second structure.

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Section: Introductionmentioning

confidence: 99%

High photoluminescence intensity of heterostructure AlGaN-based DUV-LED through uniform carrier distribution

Aman¹,

Fajri²,

Noorden³

et al. 2022

Phys. Scr.

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“…[11][12][13] The barrier of EBL could simultaneously deteriorate the injection of holes in DUV light-emitting diodes (LEDs), which already suffer from p-type doping. Then, a series of modified singlelayer EBL, such as a V-shaped graded barrier, [14] step-graded superlattice, [15] and double-side grading barrier, [16] have been proposed theoretically to mitigate the injection deterioration of holes. While the validity of the above EBLs needs to be further proved, the enhancements of EQE by 2.7 and 2 times in AlGaN DUV LEDs at 250 [17] and 270 nm, [18] respectively, by replacing the single-barrier EBL with multibarrier ones have been exhibited.…”

Section: Introductionmentioning

confidence: 99%

Resonant Tunneling Effects on the Double‐Barrier Electron Blocking Layer of a Nitride Deep‐UV Light‐Emitting Diode

Gao

et al. 2023

Physica Status Solidi (b)

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The multi‐quantum‐barrier electron blocking layer (EBL) is reported to significantly improve efficiency by nearly 3 times over a single barrier in deep‐UV AlGaN light‐emitting diodes to deal with electron leakage. The improvement is usually attributed to the enhanced effective barrier height, and this article aims to explore the benefits of the tunneling effect by calculating the tunneling currents of electrons and holes through an Al0.6Ga0.4N/AlyGa1−yN double‐barrier EBL under external bias from opposite directions. The results show that the tunneling current for holes Jh is several orders of magnitude higher than that of the electrons Je as the barriers are with Al mole fraction y greater than 0.75 and thickness larger than 2 nm, which promises effective hole injection by tunneling without much electron leakage. Tunneling mechanism works better in EBL with higher and thicker barriers because the tunneling coefficients of light hole drop much slower than electrons due to its small effective mass. A proper distance between the barriers is needed to avoid electron leakage while holes tunnel through the EBL. Built‐in electric fields tilt the band to enlarge the peak‐to‐valley ratio. This work indicates that the tunneling effect substantially facilitates a multibarrier EBL to enhance carrier‐injection efficiency.

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“…where C n and C p are Auger recombination rates for electrons and holes, respectively. causes efficiency droop and strongly influences the optical output power of LEDs, especially at high current densities [18]. However, the corresponding values of electron and hole concentrations in the NUV LED are respectively 8.21×10 15 and 3.79×10 15 cm −3 , which are one order of magnitude higher than those of the blue LED.…”

Section: Introductionmentioning

confidence: 99%

Improved performance of InGaN/GaN Near-UV light-emitting diodes with staircase hole injector

Kim

et al. 2021

Eng. Res. Express

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We report the enhanced performance of near-ultraviolet (NUV) InGaN/GaN multiple quantum-well (MQW) light-emitting diodes (LEDs) with a staircase hole injector (SHI). Simulation results indicate that the internal electrostatic field in the QW of the LED-SHI is decreased owing to the reduced sheet charge density at the interface between QW and quantum barrier (QB) caused by the smaller In content difference. Additionally, the SHI structure in the QBs suppresses the ballistic or quasi-ballistic hole transport, thus enhancing efficient hole injection into the QWs. The radiative output power of an LED-SHI is increased by 25.3% at 300 mA over that of conventional LEDs with GaN QBs. The droop of internal quantum efficiency (IQE) an LED-SHI at 300 A·cm−1 is 6.1%, while the LED with GaN QBs has an IQE droop of 17.7%. The reduced IQE droop and increased radiative output power in the LED-SHI is attributed to the reduced hole overflow, increased hole injection into the MQW and the decreased electrostatic field in the MQWs. The results show that the SHI structure in the LED is promising for improved performance in high-power GaN-based NUV LEDs.

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Suppression of efficiency droop in AlGaN based deep UV LEDs using double side graded electron blocking layer

Cited by 18 publications

References 36 publications

High photoluminescence intensity of heterostructure AlGaN-based DUV-LED through uniform carrier distribution

High photoluminescence intensity of heterostructure AlGaN-based DUV-LED through uniform carrier distribution

Resonant Tunneling Effects on the Double‐Barrier Electron Blocking Layer of a Nitride Deep‐UV Light‐Emitting Diode

Improved performance of InGaN/GaN Near-UV light-emitting diodes with staircase hole injector

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