Paper
6 February 2012 Effect of dislocation density on efficiency curves in InGaN/GaN multiple quantum well light-emitting diodes
Yoshiyuki Harada, Toshiki Hikosaka, Shigeya Kimura, Maki Sugai, Hajime Nago, Koichi Tachibana, Naoharu Sugiyama, Shinya Nunoue
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Abstract
The contribution of reduction of threading dislocation densities (TDDs) to optical properties is investigated for InGaN/GaN light-emitting diodes (LEDs) grown on sapphire substrate. The external quantum efficiency (EQE) curves depending on the TDDs are discussed both theoretically and experimentally. At the current density of <20 A/cm2, the EQE increases with decreasing the edge-type TDD from 5 e8/cm2 to 2 e8/cm2. The current density at the maximum EQE shifts to lower value as the edge-type TDD decreases, whereas the EQE presents no remarkable difference in the highercurrent density range irrespective of the TDD. According to the rate equation (ABC) model, the peak shift reflects the Shockley-Read-Hall non-radiative process (A coefficient). Analysis of the photoluminescence (PL) decay and the dependence of integrated PL intensity on excitation power reveals that the threading dislocations act as non-radiative recombination centers in the multiple quantum well active region. The TDD of <2 e8/cm2 is required for highly efficient blue LEDs operating at current density of around 15 A/cm2, whereas the TDD of <5 e8/cm2 in required for the LEDs operating at around 50 A/cm2.
© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Yoshiyuki Harada, Toshiki Hikosaka, Shigeya Kimura, Maki Sugai, Hajime Nago, Koichi Tachibana, Naoharu Sugiyama, and Shinya Nunoue "Effect of dislocation density on efficiency curves in InGaN/GaN multiple quantum well light-emitting diodes", Proc. SPIE 8278, Light-Emitting Diodes: Materials, Devices, and Applications for Solid State Lighting XVI, 82780J (6 February 2012); https://doi.org/10.1117/12.907679
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Cited by 3 scholarly publications.
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KEYWORDS
External quantum efficiency

Light emitting diodes

Quantum wells

Blue light emitting diodes

Luminescence

Optical properties

Quantum efficiency

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