Mechanism of hole injection enhancement in light-emitting diodes by inserting multiple hole-reservoir layers in electron blocking layer

Journal Article · Mon Mar 14 00:00:00 EDT 2016 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4942881· OSTI ID:22596890

Zhao, Yukun; Wang, Shuai; Feng, Lungang; Li, Yufeng; Ding, Wen ^[1]; Yun, Feng ^[1]; Su, Xilin ^[2]; Guo, Maofeng ^[3]; Zhang, Ye ^[3]

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1. Key Laboratory of Physical Electronics and Devices of Ministry of Education and Shaanxi Provincial Key Laboratory of Photonics and Information Technology, Xi'an Jiaotong University, Xi'an, Shaanxi 710049 (China)
2. Shaanxi Supernova Lighting Technology Co. Ltd, Xi'an, Shaanxi 710075 (China)
3. Solid-State Lighting Engineering Research Center, Xi'an Jiaotong University, Xi'an, Shaanxi 710049 (China)

In this study, gallium nitride (GaN) based light-emitting diodes (LEDs) with single and multiple hole-reservoir layers (HRLs) inserted in the electron-blocking layer (EBL) have been investigated numerically and experimentally. According to simulation results, a better electron confinement and a higher hole injection level can be achieved by the multiple HRLs inserted in the EBL region. To further reveal the underlying mechanism of hole injection enhancement experimentally, the active regions were intentionally designed to emit photons with three different wavelengths of 440 nm, 460 nm, and 480 nm, respectively. Based on the experimental results of photoluminescence (PL) and time-resolved PL (TRPL) measurements conducted at 298 K, the remarkable enhancement (148%) of PL intensities and significant increase in the decay times of the quantum wells close to p-GaN can be obtained. Therefore, the mechanism is proposed that carriers are able to reserve in the EBL region with multiple HRLs for a much longer time. Meanwhile, carriers could diffuse into the active region by tunnelling and/or thermo-electronic effect and then recombine efficiently, leading to the better carrier reservoir effect and higher hole injection in LEDs. As a result, by inserting multiple HRLs in the EBL region instead of single HRL, the experimental external quantum efficiency is enhanced by 19.8%, while the serious droop ratio is markedly suppressed from 37.0% to 27.6% at the high current injection of 100 A/cm{sup 2}.

• OSTI ID: 22596890
• Journal Information: Journal of Applied Physics, Vol. 119, Issue 10; Other Information: (c) 2016 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
CARRIERS
CHANNELING
ELECTRONS
GALLIUM NITRIDES
HOLES
INJECTION
LIGHT EMITTING DIODES
PHOTOLUMINESCENCE
PHOTONS
P-TYPE CONDUCTORS
QUANTUM EFFICIENCY
QUANTUM WELLS
TEMPERATURE RANGE 0273-0400 K
TIME RESOLUTION
TUNNEL EFFECT
WAVELENGTHS