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J Christen - One of the best experts on this subject based on the ideXlab platform.
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an improved carrier rate model to evaluate internal quantum Efficiency and analyze Efficiency droop origin of ingan based light emitting diodes
Journal of Applied Physics, 2012Co-Authors: Jiaxing Wang, Lai Wang, Lei Wang, Anja Dempewolf, Mathias Muller, F Bertram, J ChristenAbstract:A carrier rate model taking carrier delocalization into account is presented to analyze current dependent internal quantum Efficiency of InGaN based light-emitting diodes (LEDs). By fitting normalized experimental internal quantum Efficiency-current curves, both injection Efficiency and Radiative Recombination Efficiency depending on current can be obtained. Based on the fitting results from two LED samples with and without the InGaN interlayer beneath the active regions of 5 InGaN quantum wells (QWs), carrier delocalization and carrier leakage are believed to lead to the Efficiency droop effect under considerable and even larger injection, respectively. By investigating two LED samples with 8 and 10 QWs, it is found that the 8-QWs LED has the highest Radiative Recombination Efficiency over 80% and the 10-QWs one has the highest injection Efficiency over 50% under 120 A/cm2. This means that increasing QW number is an effective method to suppress droop effect.
D Bimberg - One of the best experts on this subject based on the ideXlab platform.
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study of Radiative Recombination Efficiency in 28 180 a wide algaas gaas quantum wells grown by molecular beam epitaxy
Journal of Applied Physics, 1994Co-Authors: D Z Garbuzov, V P Evtikhiev, N I Katsavets, A B Komissarov, T E Kudrik, I V Kudryashov, V B Khalfin, R K Bauer, Zh I Alferov, D BimbergAbstract:The paper reports a theoretical and experimental study of the dependence of the Radiative Recombination Efficiency (ηi) on the GaAs quantum well width (Lz) in AlGaAs/GaAs quantum well structures with binary/binary superlattice confinement. Values of ηi≳60% at room temperature have been obtained for quantum wells with Lz≥40 A. It is shown that structures with Lz<40 A exhibit a sharp decrease in ηi associated with nonRadiative Recombination of the high energy part of nonequilibrium carriers in the confining layers even in the presence of comparatively high potential barriers for Γ electrons.
K Fujiwara - One of the best experts on this subject based on the ideXlab platform.
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forward and reverse bias dependence of Radiative Recombination Efficiency in green in ga n quantum well diodes
Physica E-low-dimensional Systems & Nanostructures, 2012Co-Authors: K Soejima, M Horiguchi, K Ono, H Jimi, Akihiro Satake, K FujiwaraAbstract:Abstract The relative internal quantum Efficiency in green (In,Ga)N quantum well diodes is investigated by ac photoluminescence (PL) experiments using a lock-in technique under direct photoexcitation conditions where photoexcited carriers are generated only in the wells. The Radiative Recombination Efficiency is found to be significantly varied as a function of both forward and reverse bias voltages. When the reverse bias is applied, the enhanced junction field causes a reduction of the PL intensity due to tunneling escape of carriers, although a blue-shift of PL emission energy is observed owing to the compensation of internal polarization field in the wells. A reduction of the PL intensity is also observed by increasing the forward bias, which we attribute to the reduced Radiative Recombination rate due to the decreased electron–hole wave function overlap in the wells. This finding suggests that the electroluminescence droop problem may also be caused as a result of reduced Radiative Efficiency under the high forward bias.
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interplay of external and internal field effects on Radiative Recombination Efficiency in ingan quantum well diodes
Physica Status Solidi (c), 2006Co-Authors: H Aizawa, K Soejima, Akihiro Satake, A Hori, K FujiwaraAbstract:Electroluminescence (EL) and photoluminescence (PL) properties have been investigated of the high-brightness green InGaN single quantum well (SQW) diode over a wide temperature range (T = 15–300 K) and as a function of injection current level. When the necessary forward bias conditions to get a certain current level are different, it is found that the anomalous temperature-dependent EL Efficiency varies quite differently. That is, when the current is low and thus the forward driving voltage is small, the EL quenching observed below 100 K for high injection current levels is less significant or even absent due to the efficient carrier capture. This finding is consistent with decrease of the PL Efficiency with increasing the bias over +2.5 V. These results indicate that the EL Efficiency is significantly influenced by the interplay of internal and external field effects on the carrier capture and escape processes in addition to the localization phenomena caused by In fluctuations in the SQW layer. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
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impact of the forward bias on the Radiative Recombination Efficiency in blue in ga n gan quantum well diodes with an electron reservoir layer
13th International Conference on Semiconducting and Insulating Materials 2004. SIMC-XIII-2004., 2005Co-Authors: N Otsuji, Akihiro Satake, K Fujiwara, Y Takahashi, J K Shue, U Jahn, H Kostial, H T GrahnAbstract:The temperature dependence of the electroluminescence (EL) spectral intensity between T= 20 and 300 K has been investigated in detail for two blue (In,Ga)N/GaN multiple-quantum-well (MQW) light-emitting diodes (LEDs) without and with an additional n-doped In/sub 0.18/Ga/sub 0.82/N electron reservoir layer (ERL). The Radiative Recombination Efficiency significantly changes, when the additional ERL is introduced. For high injection currents I/sub f/ i.e., large forward bias voltages V/sub f/ a quenching of the EL intensity is observed for T<100 K. Furthermore, the temperature variation of the EL intensity is stronger for the LED without the ERL than for the LED with the ERL. For low I/sub f/, i. e., small V/sub f/, however, no quenching of the EL intensity is observed for both LEDs even below 100 K due to efficient carrier capture. These results imply that the unusual evolution of the EL intensity with T and If is probably caused by variations of the actual potential field distribution due to both internal and external fields, which significantly influence the carrier capture Efficiency within the MQW layer.
Jiaxing Wang - One of the best experts on this subject based on the ideXlab platform.
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an improved carrier rate model to evaluate internal quantum Efficiency and analyze Efficiency droop origin of ingan based light emitting diodes
Journal of Applied Physics, 2012Co-Authors: Jiaxing Wang, Lai Wang, Lei Wang, Anja Dempewolf, Mathias Muller, F Bertram, J ChristenAbstract:A carrier rate model taking carrier delocalization into account is presented to analyze current dependent internal quantum Efficiency of InGaN based light-emitting diodes (LEDs). By fitting normalized experimental internal quantum Efficiency-current curves, both injection Efficiency and Radiative Recombination Efficiency depending on current can be obtained. Based on the fitting results from two LED samples with and without the InGaN interlayer beneath the active regions of 5 InGaN quantum wells (QWs), carrier delocalization and carrier leakage are believed to lead to the Efficiency droop effect under considerable and even larger injection, respectively. By investigating two LED samples with 8 and 10 QWs, it is found that the 8-QWs LED has the highest Radiative Recombination Efficiency over 80% and the 10-QWs one has the highest injection Efficiency over 50% under 120 A/cm2. This means that increasing QW number is an effective method to suppress droop effect.
D Z Garbuzov - One of the best experts on this subject based on the ideXlab platform.
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study of Radiative Recombination Efficiency in 28 180 a wide algaas gaas quantum wells grown by molecular beam epitaxy
Journal of Applied Physics, 1994Co-Authors: D Z Garbuzov, V P Evtikhiev, N I Katsavets, A B Komissarov, T E Kudrik, I V Kudryashov, V B Khalfin, R K Bauer, Zh I Alferov, D BimbergAbstract:The paper reports a theoretical and experimental study of the dependence of the Radiative Recombination Efficiency (ηi) on the GaAs quantum well width (Lz) in AlGaAs/GaAs quantum well structures with binary/binary superlattice confinement. Values of ηi≳60% at room temperature have been obtained for quantum wells with Lz≥40 A. It is shown that structures with Lz<40 A exhibit a sharp decrease in ηi associated with nonRadiative Recombination of the high energy part of nonequilibrium carriers in the confining layers even in the presence of comparatively high potential barriers for Γ electrons.
